AN ABSTRACT OF THE THESIS OF in
Title:
Boyd Ellertson Olson
(Name) for the Ph. D.
(Degree)
Oceanography
(Major) presented on August 2,
(Date)
1967
On the Abyssal Temperatures of the World Oceans
Abstract approved:
Redacted for Privacy
June G. Pattullo
In comparison with solar radiation, the energy of geothermal heat flowing through the sea bottom is extremely small; nevertheles;, this energy is not insignificant in the circulation of the bottom water.
Calculations indicate that in the deep basins of the South Atlantic the water volume transport necessary to remove this heat is at least one-tenth of the total northward flow of Antarctic Bottom Water.
Plots of mean values of near bottom salinity and oxygen versus mean potential temperatures help to trace the movement of the bottom water.
Geothermal and adiabatic warming associated with downslope flow combine to produce a deep temperature (in situ) minimum in portions of most of the deep basins of the world. Adiabatic or near adiabatic temperature gradients have been measured near the bottom in many of these basins. Evidence of superadiabatic gradients from temperature measurements made with reversing thermometers is inconclusive; however, careful measurements with closely spaced

thermometers suggest that such gradients do exist over vertical distances of a few hundred meters in some of the deepest basins.
Decreasing potential density with depth, as found in some of the
Atlantic Basins in association with sharp temperature and salinity gradients, is not necessarily an indication of unstable equilibrium.
This is demonstrated by the results of stability calculations in the manner prescribed by Hesselberg and Sverdrup (1915).

On the Abyssal Temperatures of the World Oceans by
Boyd Ellertson Olson
A THESIS submitted to
Oregon State University in partial fulfillment of the requirements for the
Doctor of Philosophy
June 1968

APPROVED:
Redacted for Privacy
Redacted for Privacy
Crm7tepartment of Oceanography
Redacted for Privacy
Dean of Graduate School
Date thesis is presented August 2, 1967
Typed by Marcia Ten Eyck for Boyd Ellertson Olson

ACKNOWLEDGMENTS
Chronologically, my first expression of appreciation should be to Dr. Wayne V. Burt, Chairman of the Department of Oceanography, who provided the opportunity for my return to school after a lapse of many years.
I am indebted to him for his realistic appraisal of course requirements and his assistance in developing my doctoral program.
For hours of stimulating discussions and written suggestions on my dissertation, I am indebted to my two major professors, Dr.
Peter K. Weyl, now Professor of Oceanography at State University of New York at Stony Brook, and Dr. June G. Pattullo. To these and the other members of my Committee--Dr. Norman H. Anderson,
Dr. Byron L. Newton, Captain John F. Tatom and Dr. Robert L.
Smith--I extend my sincere appreciation.
Arranging in absentia for typing, printing and proofreading was a formidable obstacle until Dan Panshin offered to undertake this for me, I am deeply grateful for his generous assistance in making these arrangements and in resolving the innumerable small problems that arose.
To the many others who offered assistance and encouragement-faculty members, fellow students, friends, my understanding wife and tolerant children--I am also grateful.

TABLE OF CONTENTS
L
IL
INTRODUCTION
DISTRIBUTION OF TEMPERATURE, SALINITY,
POTENTIAL DENSITY AND OXYGEN IN THE
DEEP OCEAN BASINS
Atlantic-Indian Basin
South Indian Basin
Sierra Leone Basin
Canary and Iberian Basins
Guinea and Angola Basin
Cape, Agulhas and Natal Basins
Somali Basin
Mid-Indian Basin
Wharton Basin
Southwest Pacific Basin
Central Pacific Basin
Northwest Pacific and Mariana Basins
Philippine Basin
Ill.
DISCUSSION AND CONCLUSION
IV.
BIBLIOGRAPHY
V.
APPENDICES
Page
1
12
817
91
98
101
28
36
41
12
17
22
24
42
66
67
73
77
79
83
49
53
59
61
108
126
130

Figure
1
2
3
4
5
10
11
6
7
8
9
12
13
14
15
LIST OF FIGURES
Page
Comparison of scale used for temperature this study with conventional scale.
profiles in
Deep temperature (in situ) and salinity profiles,
Atlantic-Indian Basin.
Deep sigma-Q and oxygen profiles,
Basin.
Atlantic-Indian profiles from
11
14
16
18
Deep temperature (in situ) and salinity profiles,
South Indian Basin.
20
Deep sigma-Q and oxygen profiles, South Indian Basin.
21
Deep temperature (in situ) and salinity profiles,
Southeast Pacific Basin.
25
Deep sigma-Q and oxygen profiles, Southeast
Pacific Basin.
Deep temperature (in situ) and salinity pio files,
Argentine Basin.
29
Deep sigma-0 and oxygen profiles, Argentine Basin.
30
Deep temperature (in situ) and salinity profiles,
Brazil Basin.
Deep sigma-.0 and oxygen profiles, Brazil Basin.
26
33
35
Deep temperature (in situ) and salinity profiles,
North American Basin.
Deep sigma-Q and oxygen profiles,
Basin.
North American
Deep temperature (in situ) and salinity profiles,
Sierra Leone Basin.
38
40
43

Figure
16
17
18
19
20
21
22
23
28
29
24
25
26
27
30
LIST OF FIGURES Continued
Page
Deep sigma-.0 and oxygen profiles, Sierra Leone
Basin.
Deep temperature (in situ) and salinity profiles,
Canary and Iberian Basin.
Deep sigma-Q and oxygen profiles, Canary and
Iberian Basin.
Deep temperature (in situ) and salinity profiles,
Guinea and Angola Basin.
Deep sigma-0 and oxygen profiles, Guinea and
Angola Basin.
Deep temperature (in situ) and salinity profiles,
Cape. Agulhas and Natal Basin.
Deep sigma-Q and oxygen profiles, Cape, Agulhas, and Natal Basins.
Deep temperature (in situ) and salinity profiles,
Crozet Basin.
Deep sigma-0 and oxygen profiles, Crozet Basin.
Deep temperature (in situ) and salinity profiles,
Madagascar-Mascarene Basin.
Deep sigma.0 and oxygen profiles, Madagascar-
Mascarene Basin.
Deep temperature (in situ) and salinity profiles,
Somali Basin.
Deep sigma.-0 and oxygen profiles, Somali Basin.
44
47
48
52
54
56
57
60
62
64
65
68
69
Deep temperature (in situ) and salinity profiles,
Mid-Indian Basin.
71
Deep sigma-0 and oxygen profiles, Mid-Indian Basin.
72

LIST OF FIGURES Continued
Figure
31
32
33
34
35
42
43
36
37
38
39
40
41
44
45
Deep temperature (in situ) and salinity profiles,
Wharton Basin.
Deep sigma-Q and oxygen profiles, Wharton Basin.
Deep temperature (in situ) and salinity profiles,
South Australian Basin.
Deep sigma-.Q and oxygen profiles, South Australian
Basin.
Deep temperature (in situ) and salinity profiles,
Tasman Basin.
Deep sigma-Q and oxygen profiles, Tasman Basin.
Deep temperature (in situ) and salinity profiles,
Southwest Pacific Basin.
Deep sigma -Q and oxygen profiles, Southwest
Pacific Basin.
Deep temperature (in situ) and salinity profiles,
Central Pacific Basin.
Deep sigma-Q and oxygen profiles, Central Pacific
Basin.
Deep temperature (in situ) and salinity profiles,
Northeast Pacific Basin.
Deep sigma-0 profiles, Northeast Pacific Basin.
Mean profiles of deep temperature (in situ), salinity and sigma-Q from 13 repeated casts, Northeast
Pacific Basin.
Mean profiles of deep temperature and salinity,
Northwest Pacific Basin.
Mean profiles of deep sigma-Q, Northwest Pacific
Basin.
Page
75
76
78
80
95
96
82
84
86
88
90
92
97
100
102

48
49
50
51
Figure
46
47
LIST OF FIGURES Continued
Page
Deep oxygen profiles, Northwest Pacific Basin.
Deep temperature (in situ) and salinity profiles,
Philippine Basin.
103
105
Deep sigma-0 and oxygen profiles, Philippine Basin.
107
Adiabatic processes.
Potential temperature gradient vs. depth.
Potential temperature vs. salinity, major deep ocean basins.
111
114
119
52
120

LIST OF TABLES
Table
1
2
3
4
Temperature and Salinity Increases Between
CRAWFORD Stations 1335 and 251.
Stability Function, F, for the Near-Bottom Water in the Major Basins of the World Oceans.
Stability Function, F, at Various Depths in the
Brazil Basin.
Minimum Transport Required to Remove Geothermal Heat by Advection.
Page
49
116
118
124
LIST OF PLATES
Plate
I
II
III
IV
V
VI
VII
Major Deep Basins of the World Oceans.
Temperature (In Situ) Distribution at the Deep
Temperature Minimum.
Areas in Which the Deep Temperature Minimum and Adiabatic Lapse Rates Have Been Observed.
Bottom Potential Temperature Distribution in the
Major Deep Ocean Basins.
Salinity Near the Bottom in the Major Deep Ocean
Basins.
Sigma-O [1000 x (potential density
1)11
Near the
Bottom in the Major Deep Ocean Basins.
Dissolved Oxygen Content (ml/l) Near the Bottom in the Major Deep Ocean Basins.
Page
145
146
147
148
149
150
151

ON THE ABYSSAL TEMPERATURES OF THE WORLD OCEANS
I.
INTRODUCTION
The object of this study is to examine deep oceanographic station data for evidences of terrestrial heating and to explore how this heat affects the abyssal circulation.
The inadequacy of information on ocean bottom depths, the inaccuracy of temperature and salinity measurement and the complexity of processes largely limit this examination to qualitative considerations. Because the density, hence the stability, of a water column is determined by the vertical distribution of temperature and salinity, these properties will be considered in some detail. In addition, dissolved oxygen content will be examined superficially for indications of the relative length of residence of the water in the different basins.
In the process, charts (Plates I through VII) of the major basins
(generally deeper than 5000 meters), the deep minimum temperature
(in situ), the salinity, the bottom potential temperature, the potential density and the dissolved oxygen content of the bottom water in the major basins of the world have been prepared. These plates together with vertical profiles of temperature, salinity, potential density and dissolved oxygen are used in describing the abyssal conditions.
Charts of the global distribution of potential temperature and salinity at the bottom have been prepared by Wust (1938), Dietrich

2
(1957), and Defant (1961).
The first thorough analysis was made by
Wust in the Atlantic Ocean.
It is not the purpose here to perform an extensive analysis to improve upon these charts, but rather to look more closely at the implications of the vertical temperature structure near the bottom.
Nevertheless, potential temperatures were required in this analysis, and a bottom potential temperature chart has been included.
By comparison with solar radiation, the energy of terrestrial heat flow is indeed small; however, it does not follow that
heat is inconsequential to the abyssal circulation. The average insolation at the top of the atmosphere is one-fourth of the solar constant, or about 8 x 10 cal/cm sec, of which about three-fourths (6 x 10 cal/cm2 sec) is absorbed by the earth's surface (Budyko, 1956).
By comparison, the mean terrestrial heat flow (about 1. 4 x
cal/cm2 sec) is very small; still, this comparison is not too meaningful in that it does not represent in any way the amount of heat trans-.
mitted to great depths in the ocean.
This latter is largely a function of the vertical temperature gradients, vertical current components, and eddy coefficients.
These last two factors are difficult to measure but are undoubtedly small in abyssal regions.
heat flow cannot be dismissed as unimportant in the scheme of the abyssal circulation merely because it does not rank in magnitude with solar radiation.

3
The question of the effect of variations in the temperature of the bottom water on terrestrial heat flow and associated temperature gradients in the sea bottom has been raised frequently in recent years (Taylor and Langseth, in press; and Langseth, LePichon and
Ewing, 1966).
Such variations have been documented to depths of about 1000 meters (Gordon, Grim and Langseth, 1966). As early as 1922, Tydeman attributed the renewal of water in the deep basins to the flow of heat from the earth's crust (Tydeman, 1922 and Potsma,
1958).
Kuenen (1943) recognized heat flow and tidal currents as the combined cause of renewal of this water. A. rather extensive study of the water movement and renewal in the eastern basins of the East
Indian Archipelago was based on the data collected by the Snellius
Expedition of 1929-1930 Potsma, 1958). In his study of the bottom water in the Atlantic Ocean, Wust (1933) concluded that even in the more stagnant basins (not trenches) such as the Cape Basin (A-8,
Plate I), the evidence of terrestrial heat is completely obscured by the heat of mixing and vertical components of flow.
Evidence of the warming of the bottom water by crustal heat has been reported by both physical oceanographers and geophysicists in recent years
(Gerard, Langseth and Ewing, 1962; Wooster and Volkman, 1960).
The first successful determinations of heat flow through the sea floor were made in 1950 (Revelle and Maxwell). This was done by measuring the temperature gradient in the sediment and the thermal

4 conductivity of a core sample. Lee and Uyeda (1965) estimate that as of the end of 1964, about 2000 measurements of heat flow had been made, 89% of these in oceanic areas.
Von Herzen and Langseth
(1965) estimate that for an average geothermal gradient (6 x i0
°C/m.) and a uniform sediment layer, the error in heat flow measurements is not more than 10%; otherwise the error may be as high as 20%.
The most comprehensive summary and statistical analysis of heat flow measurements is that by Lee and tJyeda (1965).
Such measurements give values ranging from less than 0. 1 to greater than
8 micro-calories per cm2 per second (i.Lcal/cm2 sec.).
Average values appear to be highest along the oceanic rises and ridges (2. 13 iJ.cal/cm2 sec. for the East Pacific Rise) and least for the trenches
(0. 94 ical/cm2 sec. for 16 Pacific trench measurements). Mean values for the oceanic basins are 1. 18, 1. 13 and 1. 34 ical/cm2 sec.
for the Pacific, Atlantic and Indian oceans, respectively.
The global mean heat flow found by Lee and Uyeda (1965) by spherical harmonic analysis is 1. 5±10% cal/cm sec. at the 95% confidence level.
The means found from averages computed for grids having an area of
9 x 1O4 square nautical miles are: Atlantic, 1. 21; Indian, 1. 35;
Pacific, 1. 53; and all oceans, 1. 42 ical/cm2 sec.
The last figure compares with 1. 47
(1965).
cal/cm2 sec. given by Von Herzen and Langseth
Nearly all of the extremely high and low values are found

within a few hundred kilometers of the crests of the oceanic rises and ridges, the lower values occuring on the flanks of these features.
For calculating the geothermal heating of bottom water circulating freely over large distances, a mean value of 1. 4 I.Lcal/cm2 Sec.
will be used. This lower value, rather than 1. 5 I.Lcal/cm2
preferred inasmuch as the deeper basins are being considered in this study.
A. larger, more convenient unit of about 44 cal/cm2 year is obtained by multiplying by the number of seconds in a year
(31, 536, 000). A description of the most commonly measured and derived parameters reflecting the deep circulation patterns will be given for each of the major deep basins of the world in the next section.
These basins are outlined at a depth of 2500 fathoms (about
4570 meters) in Plate I.
The base chart for this and the other plates is an adaptation (rescaled, cropped and reprinted) of one of a series of depth charts prepared by Anderson (1964).
A.lthough it was initially intended to study only those basins 5000 meters and deeper, scarcity of data and the importance in some regions of depths less than 5000 meters have prompted consideration of selected shallower depths, only slightly deeper than 4500 meters in some instances.
Oceanographic data were obtained primarily from the U. S.
National Oceanographic Data Center.
The basic data source was a listing of all stations in the NODC files which extended to 5000 meters or deeper (over 700 stations). This set was later supplemented

selectively by more than 300 shallower stations mostly to depths greater than 4500 meters from the NODC files plus stations taken by the author, and others gleaned from the literature or obtained by correspondence. Altogether more than 1000 stations were examined.
A few of these were not used in the analysis because of the wide gap between bottom measurements and the next deepest measurements.
The deepest measurements for each station ranged from the bottom to several hundred meters above the bottom.
The parameter of greatest interest in this study is temperature.
Plate II shows the horizontal distribution of temperatures at the deep temperature minimum (in situ). This feature is not discernible on the deep temperature traces in all basins (Plate III).
In many cases the lowest temperature is obtained from the deepest thermometer so that the minimum cannot be determined.
A. minimum must exist everywhere in order for geothermal heat to flow across the seabottom interface, but in regions of high horizontal convection the distance from the bottom to the temperature minimum is small compared to normal thermometer spacing. Detection then requires continuous sensing such as is provided by the thermograd or closely spaced, accurate reversing thermometers.
The temperature minimum has little physical significance except as the boundary between upward and downward molecular heat conduction; however, it is an easily identifiable feature in many basins which can be used in

comparison of independentl y taken measurements of temperature, salinity, and other oceanographic variables.
Potential temperatures were computed from the new tables of adiabatic cooling prepared by Crease and Catton (1961). The horizontal distribution of potential temperature near the bottom, which was used in the computation of potential density, is shown in Plate IV.
It was initially intended to include a chart showing the horizontal distribution of salinity at the level of the deep temperature minimum; however, lack of precision and comparability in salinity measurements, coupled with the small vertical changes generally found at great depths, make this impractical.
In place of this, the approximate salinity distribution near the bottom is shown in Plate V. Where significant differences between this and the salinity at the temperature minimum occur, these are discussed in the text.
Variations in salinity attributable to errors in measurement were found to be disappointingly large and constituted the major handicap in this study.
Potential densities were computed from tables (1901).
Knudsen1 s hydrographical
Eckart (1958) has pointed out that random errors in experimental specific volume determinations (hence density) are not less than ±2 x ml/gm (±2 x 10 gm/mi for density) and that the systematic errors, which increase with pressure, are not less than
ml/gm (where p is the pressure in atmospheres).
Accordingly, he questions the necessity and realism of computing the density

to 0.001 or even 0.01 sigrna-t units.
Any examination of the stability at depths as great as 5000 meters must, however, consider density variations of this order.
Although discrepancies of the order of
0.01-0.03 sigma-t units are found at this depth between different water masses (discussed in Section II) there appears to be a consistency greater than this within a single water mass.
Thus, some useful conclusions can be drawn even though the absolute value of the density is subject to considerable error.
Sign-ia-O, the abbreviated expression of potential density i(potential density - 1.0) x 1000] was used in plotting graphs and charts and is used interchangeably with potential density in the text. Its horizontal distribution in the major deep basins is shown in Plate VI. The potential density was used in reconciling divergent salinity observations and postulated water movement.
Although the potential density is a conservative property and is thus useful in following water masses, its vertical distribution is not a measure of stability as has sometimes been assumed.
Hesselberg and Sverdrup pointed out as early as 1915 that the vertical whether the equilibrium is stable, indifferent or unstable under conditions of constant salinity.
As will be discussed later, this fails even as a qualitative indicator in the presence of a vertical salinity gradient.

Plate VII gives the mean value of the dissolved oxygen content near the bottom in each of the major basins.
Profiles for most of the major basins have also been included in the descriptive section.
Of the properties covered in this report, oxygen appears to be most subject to error.
This has been noted by several authors, particularly regarding some of the earlier determinations.
Wooster and
Volkman
(1960) noted that oxygen values at 5 km. from the
DISCOVERY II expedition were lower than others in the western
South Pacific.
Wust
(1964) discusses the differences in oxygen determinations of various cruises and concludes that the systematic errors may be as much as 15% (too low) in some instances..
Gordon
(1966) states that DISCOVERY II oxygen values used by him are about 10% too low. Although the oxygen values from DISCOVERY
II used in this report are generally low, they are not uniformly low.
Excluding two unreasonably high values, the mean of near-bottom oxygen values reported by DISCOVERY II in the Cape, Agulhas and
Natal basins is about 0. 4 ml/l lower than the mean of all other values reported in this region, whereas the mean of the bottom values of representative profiles used in this study shows adifference of 0. 7 ml/l between DISCOVERY II data and all other reports.
The depar.
ture of the DISCOVERY II values from other reported values generally increases with depth.

A brief description of the distribution of temperature, salinity, potential density, and dissolved oxygen content for each of the major deep basins of the world is given in the following section.
Representative profiles of these variables are included.
Scale expansion of these profiles, illustrated in Figure 1, facilitates examination of finer structures.
10

1
EXPANDED
100
CONVENTIONAL 5.00
COVEIT!±!
TEMPERATURE SCALE (°C)
1.50
10.00
2.00
15.00
2
2 50
20.00
Temperature scale expanded 10 times for this portion in plot at right.
4
5
Figure 1. Comparison of scale used for temperature profiles in this study with conventional scale.
I-

II. DISTRIBUTION OF TEMPERATURE, SALINITY, POTENTIAL
DENSITY AND OXYGEN IN THE DEEP OCEAN BASINS
12
Atlantic-Indian Basin
This southernmost basin, whose east-west elongation is exaggerated in the modified mercator projection, is not well defined by bathymetric surveys.
It includes the Weddell Sea and the South Sandwich Trench in its western extremity and measures nearly 1000 by
4000 kilometers at a depth of 4500 meters. Exclusive of the trench, the deepest portion of this basin appears to be in the vicinity of 58° 5.
latitude and
350
F. longitude.
Early oceanographic measurements were made in this basin by the VALDIVIA (1898-1899), the
DEUTSCHLAND (1911- 1912), the NOR VEGIA (1927- 1931), the
METEOR (1925-1926), the VIKINGEN (1929-1930), the WILLIAM
SCORESBY (1931) and DISCOVERY II (1933-1935).
In more recent years, the ELTA.NIN (1963-1965) and the OB (1957) have made measurements in this area.
The hydrographic stations taken by the
ELTANIN have been reported by the Lamont Geological Observatory
(Jacobs, 1965 and 1966).
Descriptions of the physical oceanography of the Atlantic Antarctic Ocean have been published by Brennecke
(1921), Schott (1905), Mosby (1934), Wust (1928 and 1933), Deacon
(1933 and 1937), and others.
It is now widely accepted that the Antarctic Bottom Water has its

13 origin in the Weddell Sea. Brennecke(1921) first suggested that the water formed by cooling on the shelf bordering the Weddell Sea on the southwest formed a dense bottom current. This was substantiated by
Wust (1928) and Deacon (1937).
Mosby (1934) demonstrated from the data collected by Brennecke, that the bottom water could be a mixture of Atlantic deep water and shelf water of about equal proportions.
Although the mechanism by which it is formed is not well understood, the source of this bottom water which spreads so extensively eastward and northward is not in serious dispute.
Although not evident in all of the deep temperature profiles for this basin, a layer of minimum temperature extends throughout most of it at a depth of about 4500 meters. This minimum ranges from about -0. 55 to -0. 15 °C.
In an elongated region extending west from
150 E. longitude, the temperature profiles are very similar below a depth of 1000 meters. East of 15° F. longitude the temperatures increase gradually in such a way that the slopes of the profiles between the minimum and a depth of 1000 meters become progressively steeper. Below the minimum, the slopes appear to approach the adiabatic lapse rate rather quickly, particularly in the colder part of the basin.
The top of the adiabatic layer is estimated to lie between 4800 and 5000 meters.
Temperature and salinity profiles for this basin are shown in Figure 2.
The salinity below about 3000 meters is between 34. 66 and

0
1
2 i
-
I
34.40
I
-0.50
LI
I
34.50
0.00
I I
34.60
0.50
Il I IT__Ill]
34.70
1.00
Il
34.80
1.50
T S
6
7
t
DISCOVERY II 2014 - 610 46'S. 00 35'S.
(Depth: 5394a) x ELTANIN 145 580 34'S. 23° 49'W.
o DISCOVERY II 2113
(Depth: 6657m)
580 23'S. 57° 10'S. (Depth: 5175e) i i
I
I i I
I i
I i i
I
I i i
Figure 2. Deep temperature (in situ) and salinity profiles,
AUanticTT1t2n
Basin.
A

15 and 34. 67%o .
Above 4000 meters depth there is some intrusion of higher salinity water into the northeast sector of the basin, where the
North Atlantic Deep Water gradually sinks into this basin as it flows southeastward around the tip of Africa.
This basin is essentially isohaline below a depth of 3000 meters.
Throughout the isohaline layer, the density and potential density are functions only of the temperature and potential temperature, respectively, within the limits established by the constancy of the constituents of the water, the dissolved gasses and the salts.
Using a salinity of 34. 66%o below 3000 meters and the reported salinities above this depth together with the observed potential temperatures, the potential densities were computed and are shown in Figure 3.
In the vicinity of the Weddell Sea, the potential deisity increases very slightly with depth and at a nearly constant rate below about
500 meters.
Farther east the vertical increase in potential density below 500 meters is greater and extends nearly to the bottom.
Four stations were taken by the ELTANIN in the South Sandwich
Trench in 1963.
Figures 2 and 3.
Profiles for one of these have been included in
The temperature and salinity profiles are similar to others in the western part of this basin suggesting that the water is essentially of the same origin.
At and below the oxygen minimum, the oxygen values are much higher in the Trench than at the other stations shown (Figure 3).
This suggests that this water has had a

1
02 (mI/I) _.
'&
4.0
27.60
2
5.0
rri
27.70
IHJ
7.0
6.0
27.90
27.80
''L li' *T-W
8.0
28.
.00
0
4
14
6
7
I I I I
I I i
I i I t
DISCOVERY II 2014 - 61° 46'S 0° 35's x ELT&NIN 145 - 58° 34'S. 230 49'J
0 DISCOVERY II 2113 - 58° 23'S. 57 10'E.
i
I
I t 1 1
1 I i I I I
I
1 I I i I i
I I
I I I I I
Figure 3. Deep slgma-o and oxygen profiles,
Atlantic-Indian Basin.
-

shorter residence time since its formation.
Two small basins to the west of the South Sandwich Trench (A-la
and A-lb, Plate I) are separated from this trench and the Atlantic-
Indian Basin by the Scotia Ridge and the South Sandwich Islands.
Profiles from these small basins show clear evidence of the relatively shallow sill depths (Figure 4). The easternmost basin has a minimum temperature of -0. 43 °C. between about 3500 and 3800 meters.
The temperature gradient is essentially adiabatic below 3800 meters.
In the westernmost basin temperature measurements show a minimum of -0. 14 °C.
at about 2600 meters, indicating a much shallower sill depth.
South Indian Basin
East of the Atlantic-Indian Basin neither the bathymetry nor the physical oceanography is well known.
The GAUSS traversed this area in 1902-1903 (Drygalski, 1903). Deep oceanographic stations were also taken by DISCOVERY II in this southernmost part of the
Indian Ocean in 1932, 1936 and 1938.
One deep station (3981 meters) was taken by the OB in 1956.
A single observation by the GAUSS at 58° 29' S. latitude and
89° 58' F. longitude reported a temperature of -0. 05 °C. (potential temperature of ..0. 40 °C. ) at 4661 meters. The associated salinity
(34. 40%o) is much too low to be plausible.
Salinities in this area are

0 lit
34.40
0.00
i't lII
III!
'I
34.50
0.50
I
I
34.60
1.00
1111111
34.70
1.50
lilIlillilill iii
34.80
2.00
2
.9
4
-
T
6
-
ELTANIN 286 - 600 55'S. 41° 28'W.
x ELTANIN 287 - 60° 21'S. 47° 40'W.
- Basin A-la (Depth:
5238m)
5199m)
7 ilii 111)1! till
11111111
I
I
I
I
I thu
Figure 4. Deep temperature (In situ) and salinity profiles from small basins within the Scotia Sea.
1
-
-

19 expected to be higher than in the Atlantic-indian Basin because of the addition of higher salinity water flowing downslope southeastward around the tip of Africa, mixing with the Antarctic Circurnpolar and
Bottom waters.
Farther east this is borne out by stations taken in the South Indian Basin.
The South Indian Basin is also in a region that has been poorly charted.
Its dimensions are estimated at about 700 by 1400 kilometers at a depth of 4500 meters. It is bounded on the north and east by the Southeast Indian Rise and on the south by the continental rise of
Antarctica. Its western boundary is not well defined.
The deepest known part of the South Indian Basin lies between about 110° F. and 140° F. longitude with its east-west axis at about
60° S. latitude. Maximum reported depths are between 4500 and
4800 meters.
Representative temperature, salinity, potential density and dissolved oxygen profiles for this basin are shown in Figures 5 and 6.
Striking features of these profiles are: 1) the steepened salinity gradient below 1500 meters; 2) the high bottom potential density associated with the relatively low bottom temperature and high bottom salinity; and 3) the steep, nearly constant temperature gradient.
Below 1000 meters the potential density gradient is steeper than anywhere in the Atlantic-Indian Basin.
In this relatively shallow basin, there is no observational eviden of a deep temperature inversion in the data examined.
In fact, the

Fl
1
0
T(°C) -'.
I-_i
I
IjII1
34.40
0.00
I
'I
34.50
I
I
I
34.60
III
I I
'I
I
I
34.70
1.50
I I
I
34.80
2.00
4
-
T
S
6
-
DISCOVERY II
890 - 59° 5'S. 133° 19'E.
(Depth: 4771m)
7
-t
I
I
I I I I
I
I I
I I I I
I i I i
I I I
Figure 5. Deep temperature
(in situ) and salinity profi1es South Indian Basin.
I I
-
C

1
02(mh/1)_..
I
±0
'I
I
I
II '1
21.3O
11
IIII
2'1.90
ill II
8.0
28.
00
4
6
7
-I
I i
I I
DISCOVERY II 890 - 59° 5'5 1330 19'E
I
I
I I I I
I
I I
I
I
Figure 6. Deep sigma-G and oxygen profiles, South Indian Basin.
I
III
I
I

22 temperature gradient of the deepest station in this basin (Figure 5) is nearly linear between 2500 meters and its maximum depth (4430 meters).
The in situ bottom temperature ranges between about -0. 10 and 0. 0° C.
The dissolved oxygen content in the deep waters is slightly less
(4. 4 to 4. 6 ml/l) in the eastern part of this basin than in the eastern part of the Atlantic-Indian Basir, indicating a slightly longer residence time.
In the western part of the basin, the oxygen content is comparable to that in the central part of the Atlantic-Indian Basin.
This suggests the possibility of this water being formed on the
Antarctic Shelf far eastward of the Weddell Sea.
Southeast Pacific Basin
The Southeast Pacific Basin is bounded by the continental rises of Antarctica and South America, by the Chile Rise on the north and the Albatross Cordillera on the northwest.
Its connection with the
South Indian Basin far to the west is uncertain. From the existing bathymetry, it appears that there are no passageway connecting with this basin at depths greater than 4000 meters.
Southward extensions of the Southeast Indian and South Tasmania rises and the Albatross
Cordillera appear to confine the cold core of deep circumpolar water so that it does not enter the Southwest Pacific Basin to the north.
At a depth of 4500 meters, this basin has a maximum length of about

3200 kilometers and a width of about 1900 kilometers. Deep stations have been taken in this basin by DISCOVERY II (1931-1934 and 1951), the OB (1958), the BURTON ISLAND (1960) and the ELTANIN (1963-
23
1965).
Although it has been observed throughout most of the basin, the deep temperature minimum is not confirmed by observations everywhere (Figure 7). The temperature at the deep minimum ranges from about 0. 20° C. in the southwest to greater than 0. 70° C. in the northeast part of the basin (Plate II). Shallow adiabatic gradients are evident in several profiles. These are best documented at station
408 of the OB and station 231 of the ELTANIN.
The potential temperature near the bottom ranges from about
-0. 20 to +0. 35° C.
Dietrich (1957).
This is somewhat less than the range given by
He indicates bottom potential temperatures ranging from -0. 3 to +0. 4° C. Both Dietrich (1957) and Defant (1961) show a pronounced potential temperature minimum extending along the axis of the basin. This feature is less conspicuous in the data considered here, particularly in the northeastern half of the basin.
A salinity maximum of about 34. 74%o at a depth of 1200 meters in the western end of the basin decreases and deepens to about 3000 meters in the northeastern end of the basin. This maximum reflects the high salinity water which flows southeastward from the Indian
Ocean via the South Australian Basin.
Below this maximum, the

salinity decreases gradually to values between about 34. 70 and
34. 71%o (Figure 7 and Plate V).
The relatively high salinity water entering the basin from the northwest gradually mixes with colder, somewhat fresher water entering the area of the basin farther south. As it flows eastward, the high salinity water moves downward along constant density surfaces having values between about 1. 02788 and 1. 02789 near the bottom of this basin (Figure 8 and Plate VI).
The decrease in oxygen during transit of the high salinity water from west to east appears to be more than compensated by oxygen contained in the cold, lower salinity water intermixing along these surfaces from the south. The dissolved oxygen content of the water entering the western end of this basin is high (5. 1 ml/l) compared to the oxygen content of the water in the eastern end of the Atlantic-
Indian Basin (4. 85 ml/I); however, in view of the uncertainty of these values, particularly that reported by DISCOVERY II in the eastern end of the Atlantic-Indian Basin, this difference cannot be regarded as significant.
24
Argentine Basin
The Argentine Basin is bounded by the contirental rise of South
America on the west, by the Scotia Ridge and South Georgia Rise on the south and southwest, by the MidAtlantic Ridge on the east and by

T (°C) -
34.40
0.50
34.50
1.00
34.60
1.50
34.80
2.50
T
0
ELTMIN 411 - 63° 1'S. 135° 4'W. (Depth: 4821m)
ELTANIN 444 - 620 4'S. 104° 57'I. (Depth: 5072n)
ELTANIN 225 - 56° 4'S.
7'W. (Depth: 5064m)
Figure 7. Deep temperature (in situ) and salinity profiles, Southeast Pacific Basin.
Lu

1
02 (mi/i) .__
0j
I I
2
4.0
27.60
I
I
I
5.0
27.70
I I
6.0
27.S0
I
I 1
7.0
j'I
1 1 I I
8.0
2.I
Do
0
4
M
6
-
ELTANIN 411 - 63° 1'S. 135° 4'W.
x ELTANIN 444 - 620 4'S. 104° 57'W.
0 ELTANIN 225 - 56 4'S.
79 7'W.
7
Figure 8. Deep slgma-e and oxygen profiles, Southeast Pasific Basin.

27 the Rio Grande Rise on the north. Wust's assumption (1933) of a relatively narrow passageway between the Scotia Ridge and the Mid-
Atlantic Ridge is supported by the deep minimum temperature chart of this study (Plate II). LePichon (in press) shows a narrow erosional passageway nearly
4600 meters deep through the Rio Grande Rise at the northwest end of this basin.
He estimates that the current velocity may be as high as half a knot, or more, with transport comparable to that of the Gulf Stream.
Deep hydrographic casts were first made in this basin by the
DEtJTSCHLAND (1911), the METEOR
(1925), and the DISCOVERY
(1926).
More recent deep casts have been made by the CAPITAN
CANEPA (1957-1959) and the ELTANIN (1963).
Temperature measurements do not disclose the presence of the deep temperature minimum in this basin except possibly in the extreme southwest. The maximum horizontal gradient in the bottom water is found in the southeast sector of the basin where the minimum temperature is less than
0.
20° C.
in the southeast extremity and about +0.
10° C. in the central part of the basin.
Elsewhere the minimum temperature lies between +0.
10° C. and about +0.
20° C.
There is an observable horizontal gradient in bottom salinity across this basin, although it is somewhat obscured by errors in the salinity determinations. The salinity near the bottom increases from less than 34.
66%o in the southeast to near
34. 68%o in the

28 northwest, reflecting the varying mixture of water from the Antarctic with that from the North Atlantic and, possibly, from the southeast
Pacific.
Below 2000 to 2500 meters there is a sharp decrease in both temperature and salinity with depth throughout the basin (Figure 9).
These steep vertical gradients are maintained by the southward flow of warm, saline North Atlantic Deep Water above the northward spreading Antarctic Bottom Water.
The potential density increases downward to about 4000 meters and is nearly constant below this depth.
The very steep temperature gradient near the bottom at ELTANIN station 170 appears suspect at first, especially since it is supported by but a single observation; however, this is found to be characteristic of the entrance to these deep basins where a deep passageway connects with a cold water source.
From the oxygen minimum between 1000 and 2000 meters, the dissolved oxygen content increases all the way to the bottom
(Figure 10), reflecting the predominance of water of Antarctic origin at the greater depths.
Brazil Basin
The Brazil Basin is enclosed by the continental rise of South
America on the west, the Rio Grande Rise on the south, the

0
T (°C) --
1
2
34.60
0.50
34.70
1.00
34.80
1.50
34.90
2.00
35.00
2.50
4
6
-
7
_T
I
S
ELTANIN 170 - 46° 50'S. 35 5'W. (Depth: 5614m) x METEOR 51 - 45° 58'S. 550 22'W.
(Depth: 5563ni)
-
I I I
I I I
I
I I
Figure 9. Deep temperature (In situ) and salinity profiles, Argentine Basin.
1
I
I
I
_1_,_J___.L._
-
NJ

6
7
0
4
1
2
02 (mI/I) _-.
'
4.0
27.60
I
I
I
5.0
27.70
'
I
I
6.0
27.80
I
I
1
I
I
1
7.0
27.90
I
I
I
I
I I j a .o
28, .00
ELTARIN 170 - 46° 50's. 35 5W.
g METEOR 51 - 45° 58's. 550 22W.
Figure 10. Deep sigma-O and oxygen prafiles, Argentine Basin.
-
C

31
Mid-Atlantic Ridge on the east and interrupted ridges on the north.
The basin is roughly rectangular in shape with dimensions of abot.it
1600 by 3000 kilometers at a depth of 4500 meters.
The long axis is oriented north-south. The deepest connection is with the Argentine
Basin through a narrow passageway entering the southwestern part of this basin. The sill depth connecting these two basins is between
4400 and 4500 meters (LePichon, in press). The deepest exit is into the Sierra Leone Basin through the Romanche Gap (0° 10 'S.
180 15'W., Plate I) or, possibly, a somewhat deeper, meandering connection slightly to the south (Metcalf, 1961). The sill depth between the Brazil Basin and the Romanche Gap is about 4300 meters; that between the Romanche Gap and the Sierra Leone Basin is estimated to be about 3500 meters.
Deep hydrographic casts have been made in the Brazil Basin by the METEOR (1926), the ALBATROSS (1948), the SAN PABLO
(1956), the CRAWFORD (1957, 1958, and 1963), the LOMONOSOV
(1959), the ATLANTIS (1959), the CHAIN (1961), and the JOHN E.
PILLSBURY (1963).
Temperature and salinity measurements have been taken to depths greater than 5000 meters at more than 30 stations in the basin proper. In addition, measurements at depths greater than 7000 meters have been taken in the Romanche Gap.
The relatively warm North Atlantic Deep Water entering from the northeast is confined along the eastern slopes of the basin by the

leftward deflection of Coriolis force.
32
Similarly, the cold, less saline
(but denser) Antarctic Bottom Water flowing in from the west and southwest is deflected toward the left along the western slopes beneath the North Atlantic Deep Water producing east-west bottom gradients in both temperature and salinity. Because of the steep vertical gradients in temperature and salinity, their values at the bottom vary appreciably with the basin depths, higher values being found in the more shallow parts.
A deep temperature inversion is found in the northern half of this basin except along the weStern edge, where the Antarctic Bottom
Water enters. The associated minimum temperature is at a depth of
5400 meters at CRAWFORD station 1364 and shoals eastward to about
4700 meters in the Romanche Gap. The minimum temperature increases (from about 0. 65 0 C. to about 1. 10 0 C. ) as its depth decreases.
Below the minimum, the temperature gradient rapidly approaches the adiabatic gradient (Figure 11).
Over much of the deep basin, the bottom salinity is between 34. 70 and 34. 71% ; along the western extremity, however, it approaches
34. 69%o, and in the northeast corner it increases rapidly to 34. 76%o.
Vertically above the bottom, the salinity increases about 0. 2%c in
2000 meters (Figure 11), which is probably the steepest gradient to be found anywhere at this depth.
2° C.
The temperature increases nearly
(upward) over this same depth interval (Figure 11). Associated

a
2
0
T(°C) -
I I
I
I
1
I
34.60
1.00
I
I
I
I I I I
I
34.70
1.50
I'
I
I ' I p
34.80
2.00
1 I
I
I I
I
34.90
2.50
I
[I
I
I
I
I
I
T
6
7
T
CRAWFORD 1364 60 59S. 25° 8'W. (Depth: 5755u*) x ATLANTIS 578]. - 18° 0'S. 29° O'W.
(Depth: 5077m)
I I i_1i_i
I I I I I
I i
I I
I
I
I I I
I
I I I I
I
I
I I I I
Figure 11. Deep temperature (In situ) and salinity profiles, Brazil Basin.
I I I I I

34 with this vertical distribution of temperature and salinity is a potential density profile suggesting a deep unstable layer (Figure 12).
This suggestion is misleading, however, and results from the failure of sigma-O to take into account differences in the compressibility of water at different temperatures and at different salinities.
It will be shown in the next section that the equilibrium is stable in this basin and in the North Atlantic basins in which the sigma-e decreases or is nearly constant with depth near the bottom.
There is a striking difference in the deep oxygen profiles of the
Argentine and Brazil basins (Figures 10 and 12).
Although the bottom values range between about
5. 0 and
5. 5 ml/l in both basins, the gradients above the bottom are of opposite signs.
The oxygen decreases upward in the Argentine Basin, whereas it increases from the deep temperature minimum to about
3500 meters in the Brazil
Basin.
This increase is a reflection of the shorter residence time of the North Atlantic Deep Water in the lower latitudes nearer its source.
The coldest water from the eastern Brazil Basin is excluded from the Romanche Gap by the intervening sill, which has a depth of about
4300 meters; thus, the water in the deepest part of the Romanche
Gap is nearly 0.
5° C.
(potential temperature) warmer and 0.
04%o saltier than that in the deepest part of the Brazil Basin.
Above the sill depth, the temperatures, salinities and potential densities are

1
2
I iii iiiii
z'r.bu
11111111 z.,.iu
11111111 IIII I 1111111111 III
9.0
00 a
.9
g
4
Os
M
6
-
-
7 cRAWFORD 1364 6° 59'S. 25° 8'W.
ATLANTIS 5781 - 18° 0'S. 290 O'W.
-t
I i I i
I t I i I I I i I i I i
I
I I I I I I i
I I
I
I I I I
FIgure 12. Deep slgma-O and oxygen profiles, Brazil Basin.
I
I I I
I I I I I
Ui

nearly identical.
North American and Contiguous Basins
The North American Basin occupies a major part of the western
North Atlantic Ocean.
Crescent shaped with north-south elongation, it has overall dimensions of about 2500 by 3500 kilometers at a depth of 5000 meters. This large basin connects with the smaller and somewhat shallower Newfoundland Basin to the north. This and the
Venezuelan Basin, which is separated below about 2000 meters from the North American Basin by the Antilles and their connecting ridges, will also be discussed in this section. The North American Basin is bounded on the west and south by the Antilles and the continental rise of North America; it is bounded on the east by the Mid-Atlantic Ridge.
This ridge and the continental rise converge to form narrow, shoaling passageways to the northeast and southeast.
In 1933 Wust noted the lack of deep measurements in the North
American Basin. Since then numerous oceanographic surveys have been conducted in this area, and more than 250 hydrographic casts have now been made to depths exceeding 5000 meters. The great majority of these have been from ships of the U. S. Naval Oceanographic Office and the Woods Hole Oceanographic Institution. Other ships that have made casts to these depths include: the DANA (1922), the ALBATROSS (1948), the DISCOVERY II (1957), the EXPLORER

37
(1962 and 1964), and the LOMONOSOV (1959).
It is evident that the bottom waters in this basin are of two distinct types and sources: one of Antarctic origin flowing into the basin from the southeast with an initial potential temperature of less than
1. 3° C. and a salinity of about 34. 83%o; the other entering the basin from the north with a potential temperature near 1.
80 C. and a salinity of about 34. 90%o, probably of Arctic origin. As in the
Brazil Basin, although the computed potential density is higher for the water entering from the north, the fact that this water overflows the Antarctic Bottom Water at points of contact clearly demonstrates that it is actually less dense than the latter.
The existence of a deep temperature minimum in the eastern half of this basin is substantiated by observations wherever stations extend below its level (Figure 13). This minimum has also been observed in the deeper regions elsewhere, except in the southeastern and south central part of the basin, that is, along the axis of the
Antarctic Bottom Water. Actually there are two minimum layers in this basin, the most extensive one associated with the Antarctic
Bottom Water at a depth of about 5200 meters, the other associated with the Arctic Bottom Water at a depth of about 4500-4600 meters.
In some areas (A.
J. MYER station at 22° N., 69° W., for example), these two minima are found superposed, one at or near the bottom, associated with the Antarctic Bottom Water, and the other near

0
T(°C) -
'
I
I I
I
I
J
I
I
I I
I
I
34.80
2.50
I I
I
I
34.90
3.00
I
I
I
I
I
35.00
3.50
'
I
'
I'
I
I
35.10
4.00
2
6
7
-
-
I I
T S ii
I
I
I
ATLANTIS 5220 - 17° 30'N. 56 47'W.
x CHAIN 350 - 29° 15'N. 57° 30'W.
0 CRAWFORD 864 - 37° 35'N. 58° 28'W.
KYER -- 22°N.
69°W.
I I
I
I
I
I
I
I
I
(Depth:
(Depth:
(Depth:
(Depth:
I
I
5500m)
6065a)
5180m)
5312m)
I
Figure 13. Deep temperature (In situ) and salinity profiles, North American Basin.
-

39
4500 meters, associated with the overlying Arctic water.
The bottom water entering this basin from the southeast has a minimum temperature between 1. 6 and 1.
70
C.
This is nearly 1.
00 C.
higher than the temperature of the bottom water in the northwest end of the Brazil Basin at about the same depth. Similarly, the bottom salinity (34. 83%o) of the entering water is more than 0. l%o higher than that in the northwest end of the Brazil Basin.
Mixing of the two bottom water types produces large north-south horizontal gradients in the abyssal temperature and salinity, both increasing from the southeast end of the basin to about 30° N. (Plates II, IV, and V).
North of this latitude, the temperature gradient becomes very flat, but the salinity gradient continues. Vestiges of the Antarctic Bottom
Water are evident at least as far north as 360
N.
Below about 4500 meters the potential density (Figure 14) is nearly constant with depth. Horizontally, the potential density increases from about
1. 02790 in the south to
1. 02792 in the north.
There is a large increase in the dissolved oxygen content of the bottom water between 20° N. and 40° N. (Figure 14), reflecting the rapid increase in the proportion of water of North Atlantic origin in this region. Wust (1933) estimates that the proportion of Antarctic Bottom Water changes from 32% to 5% between these latitudes.
None of the casts in the Newfoundland Basin show depths as great as 5000 meters, although depths slightly exceeding this have been

S.
33
2
4
0
1
6
7
Figure 14. Deep sigma-e and oxygen profiles, North American Basin.

reported in the deepest part of the Basin. Two stations show a well defined temperature minimum at about 4300 meters in this basin.
Deep water of the Venezuelan Basin has about the same potential temperature (3.
84° C.) and salinity (34. 97%o) as that at a depth of
1700 meters in the Brazil Basin. The effective sill depth between the Venezuelan Basin and the North American Basin appears to be about 2100 meters.
41
Sierra Leone Basin
This small triangular basin is only about 900 kilometers across its largest dimension at a depth of 4500 meters.
It is bounded on the northeast by the continental rise of Africa, on the northwest by the
Sierra Leone Rise and on the south by the Mid-Atlantic Ridge.
In the southeast, a narrow passageway conwects with the Guinea Basin.
The maximum depth in the Sierra Leone Basin appears to be about
5000 meters.
Deep hydrographic casts have been made in this basin by the
CHAIN (1961), the CRAWFORD (1957 and 1963), and the EXPLORER
(1963).
Only one station extends deeper than 5000 meters; therefore, all stations deeper than 4500 meters have been considered.
No deep minimum temperature is disclosed by the hydrographic casts in this basin, although the vertical temperature gradient decreases near the bottom. The bottom temperature lies between 2. 20

42 and 2.
300 c.
(Figure 15), with the colder temperatures in the deeper portions in the southern part of the basin. The bottom salinity is uniformly about 34. 86%o with sharply increasing salinity above the bottom (Figure 15).
The negative temperature and salinity gradients combine to give slightly decreasing potential density below about
3400 meters (Figure 16). This reflects different proportions of
Antarctic water at different levels. As in the Brazil and North
American basins, the water is in stable equilibrium; nevertheless, the combination of cold Antarctic Bottom Water flowing into this basin from the south beneath the high salinity water from the North
Atlantic does facilitate mixing.
The downward flux of salt and heat is balanced by the horizontal advection of cold, lower salinity water toward the northwest. The potential density near the bottom is between 1. 02789 and 1. 02790.
The mean value of the dissolved oxygen near the bottom is higher for this basin than for the surrounding basins (Plate VII).
This probably reflects sampling errors rather than real differences.
The oxygen values show considerable variation. Representative oxygen profiles are shown in Figure 16.
Canary and Iberian Basins
These two basins together form an elongated, irregular channel
(about 5000 kilometers long and 2000 kilometers wide at a depth of

z
4
6
7
0
8(°/ao)
T (°C) -
34.60
2.50
2
34.70
3.00
34.80
3.50
S
317 - 00 49'N. 16° 45'W.
(Depth: SOlOm)
Figure 15. Deep temperature (in situ) and salinity profiles, Sierra Leona Basin.
35.00
4.50

2
1
0
02 (iuh/I)
I
I
-
I
I I I
I I
I I I
I
6.0 7.0
I I I
I I
I I
I I
I
I
I
8.0 j I
I J I
LW
9.0
4
.9
- 6
7
-
I I I x
CHAIN
PILLSBURY
02
317
-
00
4
-
12°
N. 0
49'N 16°
20° 7'
45'W.
0-s
FIgure
I
I
I
I
16. Deep
I
I
I
I sigma-O and
I
I
I
I
I oxygen profiles,
I
1 i I
Sierra
I
I
Leona Basin.
I
I i
I I i
I i I
-
-

4500 meters) between the continental rise of Europe and Africa and the Mid-Atlantic Ridge.
The greatest depths are found near 24° N.
and 34° W.
The gradual shoaling toward the northeast is interrupted frequently by ridges and other irregular features rising above the
45 basin floor.
Thus, there are not just two, or even three, basins, but a series of basins of varying sizes and shapes.
Nevertheless, there are no sharp discontinuities in the characteristics of the bottom water, but, rather, a gradual northward transition. For this reason, these and the southern, deeper part of the West European Basin are considered together in this section.
The earliest deep measurements in these basins were by the
PLANET (1906), the MICHAEL SARS (1910), and the DEUTSCHLAND
(1911).
Later more extensive measurements were made by the
METEOR (1927).
A single station to 5352 meters was taken in the
Canary Basin by the ALBATROSS in 1948. The balance of the deep stations, and by far the most, have been taken since 1956.
These include stations taken by the CRAWFORD (1957 and 1963), DISCOVERY
II (1931, 1957 and 1958), the ATLANTIS (1962), and the JOHN E.
PILLSBURY (1963).
analysis.
In all, over 70 stations were included in this
A temperature minimum exists throughout most of these basins at depths between about 4500 and 5000 meters. Several of the stations show near-adiabatic lapse rates within 300 or 400 meters of the

bottom.
The salinity decreases sharply with depth above the temperature minimum but is constant through the adiabatic layer. Temperature and salinity combine to give potential densities that are nearly constant with depth below about 3200 meters.
The horizontal temperature gradient at the level of the deep minimum is rather weak with the minimum temperature ranging from about 2.
30
C. in the south to nearly 2. 6° C. in the extreme north.
The bottom salinity ranges from 34. 87%o in the south to 34. 91%c in the north.
The salinity at the temperature minimum is about
0. 0l% higher than at the bottom. The potential density of the bottom water is near 1.02791, increasing slightly toward the north.
From Figure 17 and Plates II and V, it is evident that both heat and salt are mixing downward in this basin, at least to the top of the adiabatic layer.
The temperature and salinity increases at various levels between CRAWFORD stations 1335 (10° N., 25° 5' W. ) and
251 (40° 13' N., 14° W.) are shown in Table 1.
The potential density (Figure 18) decreases rather sharply upward above 3200 meters at both of these stations; thus, we see that the greatest horizontal changes take place in regions where the positive curvature (curvature conducive to downward eddy transfer) is least and where the stability implied by the potential density gradient is greatest.
The oxygen profiles (Figure 18) indicate a rather large northward depletion below 3000 meters.
We might

0
4
0
T(°C) -
1
2
34.70
2.50
34.80
3.00
34.90
3.50
35.00
4.00
6
CRAWFORD 1335 - 100 O'N. 25° 5'W.
X CRAWFORD 251 - 400 13'N. 14° O'W.
(Depth: 5405in)
(Depth: 5125m)
0 DISCOVERY II 3539 - 48° 34'N. 16° 44'W.(Depth: 4821m)
FIgure 17. Deep temperature (In situ) and salinity profiles, Canary and Iberian Basins.
35.10
4.50
-J

1*
4
6
7
2
1
O2(m1/1)_.
Ue II
I
I hI.UU
I
I
I I I I
1 i i
8.0
h0.
I ci
CRAWFORD 1335 - 100 6111. 25° 5'W
* CRAWFORD 251 - 400 13'N. 14° O'W.
o DISCOVERY II 3539 - 48° 34'N. 16° 44'W.
FIgure 18. Deep sigma-G and oxygen profiles, Canary and Iberian Basins.

Stat.
1335
Depth (m) T (°C)
S (%o)
Stat.
251
T (°C) S (%o)
2000
3000
3.38
34.96
4.04
2. 67 34. 925 2. 87
4000 2. 37 34. 90 2. 56
4650 (mm.) 2. 30 34. 885 2. 52
5100 2.31
34.88
2.56
Increases
T (°C) S (%o)
35.07
0.66
0.11
34. 96 0. 20 0. 035
34. 925 0. 19 0. 025
34. 91
34.91
0. 22 0. 025
0.25
0.03
speculate that the bottom water at station 251 has arrived by downslope motion from a depth of about 3800 meters in the latitude of station 1335, has gained 0. 01% in salinity by downward mixing across the density surfaces, and has lost about 0. 3 ml/l of oxygen by oxidation processes during transit.
Guinea and Angola Basins
The Guinea Basin is here considered a shallower extension of the Angola Basin and is discussed with it because of the similarities and the spars ity of data in the former. Both basins are confined by the continental rise to the east and north and the Mid-Atlantic Ridge to the west. Whale Ridge separates the Angola Basin from the Cape
Basin to the southeast. The Guinea Basin is relatively small (600 by
1600 kilometers) and irregular with its long axis oriented east-west.

It connects with the larger (1500 by 2700 kilometers) Angola Basin to
50 the south through a narrow passageway constricted by the Guinea Rise.
From the temperature profiles of CRAWFORD stations 472 and 95, it is estimated that the sill depth between these two basins is about
4100 meters.
The water is warmed adiabatically as it descends from here to the greater depths of the Angola Basin.
The earliest deep oceanographic stations in these basins were taken by the GAUSS (1903) and PLANET (1906).
Stations were also taken by the METEOR (1925 and 1926), the DISCOVERY LI (1931), and more recently by the CRAWFORD (1952, 1957 and 1958), the SA.N
PABLO (1956), the CHAIN (1961), the ATLANTIS (1963), and the
GERONIMO (1963).
Perhaps the earliest oceanographic description of this area was by Buchanan in 1888.
Discussions of this area have been included in the writings of Wust (1933), Metcalf (1961) and others.
Flowing through the Romanche Gap, the coldest, deepest current appears in the westward extremity of the Guinea Basin.
On the basis of both temperature and salinity profiles, the sill depth between the
Sierra Leone and Guinea basins is estimated to be about 3900 meters
(2130 fathoms).
This agrees well with the latest manuscript bathymetric chart on file at the U. S. Naval Oceanographic Office, which shows a sill depth between 2000 and 2300 fathoms at about 00 SOT N.,
16° 20'
W.
The deep temperature minimum is not well documented in the

Guinea Basin, where it nevertheless is probably present at least in the eastern part of the Basin. The minimum is observed throughout the Angola Basin between depths of 3700 and 4300 meters (Figure 19), the shallower depths occurring in the southern part of the basin.
51
Near-adiabatic temperature gradients are found below about 4900 meters.
The thickness of this adiabatic or super-adiabatic layer is probably as much as 500 meters in the deeper parts of the basin.
Vertically, the salinity is nearly constant below 4500 meters
(Figure 19) except in the western Guinea Basin where the influence of the Antarctic Bottom Water entering through the Romanche Gap is greatest. Horizontally, both the temperature and salinity gradients are extremely weak in these basins (Plates hand V). The salinity at the bottom is about 34. 87 throughout the Guinea Basin and near
34. 88o in the Angola Basin. The salinity averages about
0. Ol%o higher at the depth of the deep temperature minimum than at the bottom.
Except for some indication of slight stratification in the western part of the Guinea Basin, the potential density shows little variation below 4000 meters throughout these two basins. The slight indication of decreasing potential density with depth in the deeper parts of the
Angola Basin where the salinity is constant falls within the limits of error and cannot be considered significant.

0
34.60
T(°C) 2.00
'I'l'I' l'I'I'I
I
I
34.70
34.80
34.90
2.50
3.00
3.50
IIj 11111111111111 i!lI' I
35.00
4,00
-
-
T
CRAWFORD 472 00 15'S.
O 42'W. (Depth: 5155m) x CRAWFORD 95 8° 18'S. 4° 19'E. (Depth: 5400m)
0 CRAWFORD 448 - 24° 14'S. 2° 30'E. (Depth: 5250i) s
-I I
I
I
I
I
I
I
I
I
I
I
I I
I
I
I I
I
I
1
I
I
I I I I
I i
I
Figure
19.
Deep temperature (In situ) and salinity profiles, Guinea and Angola Basins.
I
u-I
N)

53
Of particular interest in the Angola Basin is the increase in temperature below 3700 meters between CRAWFORD stations 95 in the north and 448 in the south.
This increase averages about 0. 05° C.
through a 1500-meter layer. Profiles of dissolved oxygen (Figure 20) shows evidence of its depletion between the Guinea and Angola basins.
Cape, Agulhas and Natal Basins
The three contiguous basins which are discussed together in this section form an irregular crescent shaped depression around the southern tip of Africa.
The inside arc is formed by the continental rise of Africa; the outside arc is formed by the continuum of the Mid-
Atlantic Ridge and the Atlantic-Indian Rise. Whale Ridge separates the Cape Basin from the Angola Basin, and the Madagascar Rise separates Natal Basin from the Mascarene Basin to the northeast.
Within this large depression, Cape Rise separates the Cape Basin and the Agulhas Basin, whereas the Mozambique Rise separates the latter from the Natal Basin. The overall length of the arc at a depth of 4500 meters is about 5000 kilometers.
The earliest bottom temperature measurements used in this study in these basins were taken by the GAUSS in 1901 and the
PLANET in 1906.
Subsequently, deep oceanographic stations were taken by the METEOR (1925), the DISCOVERY II (1926, 1930, 1932,
1933, 1935, 1936, 1938, 1939, and 1951), the GALATHEA (1951),

I.
4
6
7
0
02 (mi/i)
_________
1L
2 1
4.0
27.60
I
5.0
27.70
6.0
27.80
7.0
27.90
"2
CRAWFORD 472 -
0 15'S. 50 42'W.
* CRAWFORD 95 -
80 18'S. 4° 19'S.
O CRAWFORD 448 - 24° 14'S. 2° 30'S.
a-a
Figure 20. Deep sigma-e and oxygen profiles, Guinea and Angola Basins.
8.0
28.00
Ui

55 the CAPITAN CANEPA
(1957), the CRAWFORD
(1958), the VEMA
(1958), the ATLANTIS (1959 and
1963) and the NATAL
(1963).
In this region of strong horizontal gradients in temperature and salinity, it is difficult to reconcile all of the observations taken in these basins.
The strongest gradients are in the Agulhas Basin. The sample profiles of Figures 21 and 22 do not represent the full range of conditions found in these basins.
This is a region of intermixing of the relatively warm saline water overflowing the Whale Ridge from the Angola Basin and the cold, less saline water entering the Aguihas Basin from the Atlantic-
Indian Basin to the south. Water having a potential temperature of about 2. 20° C. and a salinity of about
34. 88%o from the Angola Basin flows over the sill at a depth of about
3000 meters.
The sill depth between the Aguihas Basin and the Atlantic-Indian Basin is about
3400 meters.
Water flowing across it has a potential temperature of about -0. 30° C. and a salinity of about 34. 68%o
.
These source waters mix in varying proportions to produce the widely varying characteristics found in these basins.
No deep temperature minimum is found in the oceanographic stations in this region, although the temperature traces in both the
Cape and Natal Basin rapidly steepen near the bottom. The salinity reaches a maximum near 3000 meters and decreases rapidly below this depth.
Horizontally, the minimum temperature and salinity

S
El
0
T (°C) -
' t
I
1
I
34.50
1.00
' '
34.60
1.50
F
I
F
F
34.70
2.00
I
F
I I
11
34.80
2.50
1
F F
I
F
I I
34.90
3.0
0.
4
T s
-
-
GALATREA 200 - 29° 39'S. 37° l'E. - Natal Basin (Depth: 5108m) x DISCOVERY II 1167 - 36° 1'S.
6° 32'E. - Cape Basin (Depth: 5290m)
0 DISCOVERY II 2625 - 41° 50'S. 18° 50'E. - Aguihas Basin (Depth: 5303m)
Iii liii lit iFil ililili liii I ilit tlt
liii lilt
Figure 21. Deep temperature (in situ) and salinity profiles, Cape, Aguihas and Natal Basins.
-
-
u-I

1
02 (mI/I) -
I j
I I
1
I I
4.0
27.60
I
2
1
I
I
5.0
27.70
I I
I I
6.0
27.80
I
7.0
27.90
I
1
I I
I
I
I i--I
8.0
28.
00
4
0.
Q5
2
6
-
1
-I I
I I i
GALATREA 200 - 29° 39'S. 37° 1'E. - Natal Basin x DISCOVERY II
O DISCOVERY II
1167 - 36° 1'S.
6° 32'E. - Cape Basin
2625 - 410 50'S. 18° 50'E. - Aguihas Basin
I
I
I I
I
I
I
I I
I
I
I I
I I
I
I I i
I
I
I
I i
I
Figure 22. Deep sigma-O and oxygen profiles, Cape, Aguihas and Natal Basins.
I I
U-I

decrease from about 1.
100 C. and 34. 74%& in the northeastern part of the Cape Basin to about 0.
10° C. and 34. 69%o in the southern extremity of the Agulhas Basin.
The salinity is about 34. 69%o in the
Natal Basin and the temperature is between about 0. 50 and 0.
60° C.
Following the method of Wust (1933), the proportions of water from the Atlantic-Indian Basin have been computed for several points.
These were found to be 60% in the northern Cape Basin, 80% in the
Natal Basin, and 92% in the central part of the Agulhas Basin.
Smooth curves drawn through the computed sigma-Q values of
Figure 22 would show increasing density and thus stable stratification all the way to the bottom.
This is consistent with the strong vertical temperature and salinity gradients.
Although the computed potential density decreases near the bottom at the representative station in the Natal Basin (GALATHEA 200), stability calculations show this water to be in stable equilibrium.
The oxygen profiles (Figure 22) indicate a shorter residence time for the near-bottom water of the Natal Basin than for that of the other two basins; however, this interpretation must be accepted with reservation because of inaccuracies in oxygen determinations and imperfect understanding of its depletion processes.
The oxygen content near the bottom ranges between about 4. 4 and 5. 0 ml/l in these basins. As has been noted previously, the DISCOVERY II oxygens appear to be low at great depths.

59
Crozet Basin
This somewhat diamond shaped basin is about 2000 kilometers in its north-south dimension by 1200 kilometers in the east-west axis at a depth of 4500 meters. It is bounded by the Atlantic-Indian Rise and the Mid-Indian Rise, which converge to form the northern apex, and ridges connecting the Kerguelen and Crozet Islands to the south.
It appears that the deepest passage into this basin connects with the
Atlantic-Indian Basin through these two groups of islands.
The sill depth of this passage is estimated from the potential temperature and salinity to be about 2700 meters.
Although the deepest part of this basin is slightly greater than
5000 meters, no oceanographic stations were found extending to this depth and only two reached below 4500 meters.
the VEMA (1960) and the ARGO (1962).
These were taken by
In addition, one station taken by the OB (1956) reached to a maximum depth of 4455 meters.
No deep temperature minimum is found on the temperature profiles constructed from data from these three stations (Figure 23) although there is a marked decrease in the vertical temperature gradient below 4000 meters in the northern end of the basin.
The bottom temperature increases from near o.4
C.
in the southern part of the basin to nearly 0. 7
°
C. in the northern extremity.
The bottom salinity increases from about 34. 68%o in the south to near

U
2 z
0.
4
6
-
7
-t
1
0
T(°C) -
-
'
I
'
I
T
I
34.40
1.00
I
34.50
1.50
[
I
I
34.60
2.00
I
ARGO LUS 111 ?° 45'S. 63° 58'E. (Depth: 4817m) x VEMA 62 - 300 21 S. 67° 15'S.
(Depth: 4892m)
I
S
I
I
I
I I
I I I I
I i i t
I
I
I I
Figure 23. Deep temperature (in situ) and salinity profiles, Crozet Basin.
I
I
I
1
-
C

61
34. 70%o in the north (Plate V).
Vertically, the salinity increases continuously with depth below
3000 meters (Figure
23).
The potential density near the bottom is about 1.
02786
(Figure
24).
The mean dissolved oxygen content near the bottom is about
4. 9
(Figure
24).
This basin shows only slight stability below
4000 meters.
The stability below
3000 meters is greater than that indicated by the potential density distribution for the same reasons advanced for the
Brazil Basin and amplified in the next section.
Madagascar-Mascarene Basins
This T-shaped complex of basins has maximum dimensions of about
1600 kilometers (north-south) by about 1800 kilometers (eastwest) at a depth of
4500 meters. Mascarene is the name given to the northward extension of the larger, deeper Madagascar Basin.
These basins are bounded by the Atlantic-Indian Rise on the south and east, Madagascar and the Madagascar Rise on the west, and a series of islands and connecting minor ridges to the north. From the temperature and salinity profiles, it is concluded that the deepest exchange is with the Crozet Basin and takes place at a maximum depth of about
4000 to
4200 meters.
The deepest stations in these basins were taken by the VITYA.Z
(1960), the ARGO
(1962) and the ATLANTIS
(1963).
None of these stations extend to a depth of
5000 meters and only five were found

02 5.0
6.0
7.0
FIgure 24. Deep sigma-e and oxygen profiles, Crozet Basin.
N.)

63 deeper than 4500 meters.
To a depth of about 3800 meters, the vertical temperature gradient is very steep in these basins.
Below 3800 meters it decreases considerably, then reverses itself rather suddenly below about 4700 meters.
Two of the Atlantis stations show superadiabatic gradients between the bottom two observation levels in the Mascarene Basin.
Because such a gradient is supported by only one measurement in each instance and because the gradient would be reduced to adiabatic or less by allowing for possible measurement error, its validity is uncertain.
The deep minimum temperature is about 0. 90° C. in the southern end of the basin and increases but slightly to less than
1. 00 C. in its northern end (Figure 25). The salinity below this depth is about 34. 7l%o; it shows slight change vertically but increases somewhat northward. The mean potential density is about 1. 02786 and the mean dissolved oxygen content is about 4. 85 ml/l at these depths (Figure 26).
It appears that the deep water in these basins arrives along constant density surfaces from the Crozet Basin with slightly increased potential temperature and salinity caused by vertical mixing.

1
0
T(°C) -
34.40
1.00
34.50
1.50
34.60
2.00
34.70
2.50
34.80
3.00
4
-
6
-
T
ARGO LUS 109 - 26° 51'S. 58° 15'S. (Depth: 5450m) x ATLANTIS 219 - 23° 32'S. 50° 13'S. (Depth: 4896m)
S
-I
I
I I I
I
I
I
I
I
I
I I I I
I I I
I
I
I
Figure 25. Deep temperature (In situ) and salinity profiles, Madagascar-Mascarene Basin.
I I I I
-
-

0
02 (ii/
0
__
,.uu
II' Iii III
I
I
I I
5.0
I
6.0
II
1
7.0
I
I 11111
8.0
2800
F.
4
-
02
ARGO LUS 109 - 26° 51'S. 58° 15'E.
x ATLANTIS 219 - 230 32'S. 500 13'E.
0e
I i I I
I
I I I I
I I I I
I I i I
I I
I
I I
Figure 26. Deep sigma-O and oxygen profiles,
Madagascar-MasCarene Basin.
I
I
u-I

Somali Basin
This small
(300 by
1600 kilometers) elongated basin is distinctly separated from the basins to the south by Madagascar, the Seychelles-
Mauritius island groups and connecting ridges.
From the temperature profiles, it is estimated that the maximum effective connecting depth between the Somali and Mascarene Basins is about
3800 meters.
This is near the maximum connecting depth
(3750 meters) through the passage between the Farquhar Island Group and Madagascar (about
110 S and
50° W) as indicated on manuscript charts on file at the
U. S. Naval Oceanographic Office.
Deep oceanographic stations have been taken in the Somali Basin by the ALBATROSS
(1948), the ARGO
(1962 and
1964) and the
ATLANTIS
(1963).
The deep temperature minimum is clearly evident in the Somali
Basin at a depth of about
4700 meters.
The temperature gradient becomes adiabatic below about
4900 meters.
The salinity below a depth of 5000 meters is nearly uniform throughout the basin at
34. 725%o.
The average salinity of the deepest measurements at
15 stations within the basin is
34. 723%o.
This water appears to come almost entirely from the Mascarene Basin or other regions to the south.
Its deepest potential temperatures and salinities are nearly the same as those at about 3700 meters in the Mascarene Basin,

which suggests that this water has moved along a constant density surface from that level. A marked increase in the salinity above
2400 meters suggests that this intermediate water comes from the
Arabian Sea and the gulfs emptying into it.
The mean values for the deepest potential density and oxygen determinations are 1. 027855 and 4. 43 ml/l, respectively.
Profiles of temperature (in situ) salinity, potential density
(Cr0) and oxygen are shown in Figures 27 and 28.
67
Mid-Indian Basin
The Mid-Indian Basin is well defined by the Mid-Indian Rise to the west, the Amsterdam-Naturaliste Ridge to the south and the
Ninety East Ridge to the east. The latter separates the Mid-Indian
Basin from the Wharton Basin. Recent bathymetric soundings indicate that the shape of this basin is more rectangular than is shown on the base charts used in this study. At a depth of 4500 meters it is nearly
3000 kilometers in its longest dimension by about 1600 kilometers in width.
The earliest deep oceanographic station found for this area was taken by the SNELLIUS in 1929.
Since then deep stations have been taken by the ALBATROSS (1948), the OB (1957), the VITYA2 (1960 and 1962), the ARGO (1960 and 1962), the DISCOVERY (1964) and the PIONEER (1964).
Several of the deep salinities reported by the

0
T(°C) -
'
I
I
-
'
I
34.60
1.50
I
I
34.70
2.00
I
I
I
I
'I
34.80
2.50
I
I
I
'
I
I
I
34.90
3.00
I
I
35.00
3.50
2
0
4
111
6
-
-
T S
ATLANTIS x ATLANTIS
144 - 30 435 490 22'E.
129 - 5 O'N. 54
(Depth: 5024m)
S.5'E.(Depth: 5141m)
0 ATLANTIS 140 - 00 57'S. 51° 23'E.
(Depth: 5106m)
I I I I I I
I
I
I
I I
I
I
I I
I
I
I I
I I I
Figure 27. Deep temperature (in situ) and salinity profiles, Somali Basin.
I
I I
I I
-

0
0
4
02 (mI/i)
27.60
4.0
27.70
5.0
27.80
6.0
27.90
7,0
28.00
8.0
Figure 28.
Deep sigma.o
and oxygen profiles, Somali Basin.

70
VITYAZ appear to be unreasonably low compared to measurements by other ships in the area.
The deep temperature minimum is found throughout this basin, generally at depths between about 4000 and 4500 meters (Figure 29).
An adiabatic temperature gradient is evident at several stations below about 4300 meters.
There is little horizontal change in the temperature at the depth of the minimum with the temperature ranging between 1. 30 and
450
C.
The Vema Trench to the west has a minimum temperature of 1.5 9° C. (reported by the DISCOVERY) at a depth of about 3550 meters (Figure 29).
It is separated from the
Mid-Indian Basin below a depth of 3200 meters.
The salinity below the deep temperature minimum in the Mid-
Indian Basin is nearly constant at about 34. 72%o (Plate V and
Figure 29).
The mean of the deepest measurements excluding the extremely low values reported by the VITYAZ is 34. 7l8%o. Because of the variability of the reported salinities and small number of observations, this is not considered significant beyond the second decimal place.
In view of the slight vertical salinity gradient in the deep water of this basin, the potential density profiles probably reflect the stability rather accurately.
These profiles show little or no displacement stability below aEout 3600 meters (Figure 30). The dissolved oxygen content (Figure 30) increases continuously with depth

2
0
4
Q5
0
T(0C) -
34.60
1.50
34.70
2.00
34.80
2.50
34.90
3.00
0
ARGO MON 111-15 - 12° 58'S. 75° S'E.
x PIONEER
442-020 20 28.3'S. 84° 3.8'E.
DISCOVERY II
(Depth: 5139in)
(Depth: 4544m)
5341 - 9° 10.3'S. 67° 35.7'E. (Depth: 6180m)-Vema Trench
Figure 29. Deep temperature (in situ) and salinity profiles, Mid-Indian Basin.
35.00
3.50

4.0
)'7'7fl
. . .
)7Qn
I
6.0
7.0
0
02 (mi/i) _....
a I ULI
1
2
0
4
0.
Izi
I
6
7
-
-
ARGO MON 111-15 - 12° 58'S. 75° 5'E.
x PIONEER 442-020 2° 84° 3.8'E.
0 DISCOVERY II 5341 - 9° 10.3'S. 67° 35.7'E.-Vema Trench
I liii iii
I
It nil I Iii iii iii
I I
I ii ii ii it
Figure 30. Deep sigma-G and oxygen profiles, Mid-Indian Basin.
-
-
C'.)

in the Mid-Indian Basin, although this increase is small below 4000 meters. This reflects the shorter residence time plus, perhaps, a lower oxidation rate in the bottom water.
73
Wharton Basin
The Wharton Basin connects with the Java Trench and a smaller basin to the southeast, sometimes referred to as the West Australian
Basin.
This latter is often regarded as an extension of the Wharton
Basin as it will be in this study. The Wharton Basin is rectangular shaped and has dimensions of about 1400 by 1700 kilometers at a depth of 4500 meters, elongated to the southeast by another 1400 kilometer oval comprising the West Australian extension.
Thus this system of basins and trench is bounded on the east and north by the continental rise of Australia and Indonesia, on the south by the
Southeast Indian Rise, and on the west by the Ninety East Ridge.
Manuscript bathymetric charts at the U. S. Naval Oceanographic
Office show passageways interconnecting these basins at depths greater than 5000 meters. They also indicate that the sill depth between this system and the South Australian Basin is about 5000 meters. Because of the variability of depths within the Wharton complex, tlaere is not the consistency of temperature profiles found in some basins and the effective depth of interchange as determined from the temperature profiles is less than 5000 meters in most cases,

74 and as shallow as 4000 meters in some.
The earliest deep oceanographic stations reported for this area were taken by the SNFLLITJS and DANA. in 1929.
More recent deep stations have been taken by the DISCOVERY 11(1936, 1937, 1950 and
1951), the ALBATROSS (1948), the GA.LATHEA. (1951), the OB (1957), the DIAMANTINA (1957 to 1963), the VITYAZ (1959 and 1962), the
VEMA (1960), the GASCOYNE (1962 and 1963), the ARGO (1962), the
KOYO MARU (1963 and 1964) and the PIONEER (1964).
The depth of the deep temperature minimum in the Wharton
Basin is quite variable. It is present nearly everywhere between about 4000 and 4700 meters, with an adiabatic gradient below 4500 meters in part of the basin (Figure 31), somewhat deeper in other parts.
Horizontally, the minimum temperature ranges between about 0. 90 and 1. 20° C.
The salinity is nearly constant below 4500 meters at about 34. 71%o, or slightly higher. The potential density is also nearly constant below 4500 meters at about 1. 02785 to 1. 02786
(Figure 32).
The 1. 02785 constant potential density surface slopes upward from 5000 meters to about 4200 meters in the South Australian
Basin.
The oxygen increases continuously with depth to about
4. 4-4. 6 ml/1.

F..
4
6
0
T(°C) -
-
1
2
34.50
1.50
34.60
2.00
34.'TO
2.50
34.80
3.00
S
DIAMANTINA 56 - 2° 58.3'S. 92° 0.9'E
2'E. (Depth: 5852m)
ODIAMA14TINA 3-427 - 9° 0'S. 104° 16 E. (Depth: 5669m)
Figure
31.
Deep temperature (In situ) and salinity profiles, Wharton Basin.
34.90
3.50
U,

I I I i
I
I
7
1
4
6
-
-
_.9?
Z1.1U
02 (mi/i) -_
I
'
I
I
3.00
27.60
I
I
I i.
I
&I.ou
[1I
02
08
. DIAMANTINA 3-441 - 26° 41'S. 108° 2'E.
x PIONEER 56 - 2° 58.3'S. 92° O.9'E.
ODIAMANTINA 3-427 - 9° 0'S. 104° 16'E.
I
I
I
I
I
I
I
I
I
I
Figure 32. Deep sigma-9 and oxygen profiles, Wharton Basin.
.,
7.00
An
C'

77
South Australian Basin
The ma basin of this system is oval shaped with a long dimension of about 2500 kilometers. It is bounded on the north by the
Australian continental slope, on the south by the southeast Indian Rise and on the east by the South Tasmania Rise. At its westward end, a series of smaller closely related basins extend northwestward for about 1000 kilometers farther. Thus, the South Australian Basin as considered here has overall dimensions of about 3500 by 1000 kilometers at a depth of 4500 meters. The smaller basins have depths in excess of 5500 meters, and the main basin has an extensive area of about this depth.
These basins are interconnected at 5000 meters or deeper.
The five stations from this basin used in this study were all taken by the DIAMANTINA in 1960.
The salinities of three of these stations appear to be 0. 02 to 0.
03%o too high judging from the salin-.
ities of adjacent basins and the probable potential density.
The deep temperature minimum is recorded at all of the stations between about 4200 and 4700 meters, with the greatest depth in the eastern part of the basin (Figure
33).
Adiabatic or slightly superadiabatic gradients exist below 4500 to 5200 meters on all but one of the five profiles. The lowest reported minimum (0. 82° C.
) is at the western end of the main basin; the highest reported minimum is in

2
0
0
Os
4
0
I
I
(
F
I
34.50
1.00
1
I
34.60
1.50
34.130
2.50
-
-
T S
DIAMANTINA 21 340 59'S. 102° 42'E. (Depth: 6857m) x DIMLANTINA 84 40° 7'S. 134° 11'L (Depth: 5486nt)
-I
I I
I
I I I
I
I
I
I
I
I I I I
I I I
I t
I I I
I
I I
Figure 33. Deep temperature (in situ) and salinity profiles, South
Australian Basin.
I
I
I
I
I
34.90
3.00

the most northwesterly of the smaller basins. The coldest water spreads along the southern part of the basin producing a weak northsouth gradient.
The salinity below 4800 meters is near 34. 7l%o throughout the basin (Figure 33) complex. The potential density below 4800 meters appears to be just less than 1. 02786 (Figure 34).
In the main basin, the dissolved oxygen content increases continuously with depth to about 4. 6 to 4. 7 ml/l (Figure 34).
The most northwesterly station shows a deep oxygen minimum at the top of the adiabatic layer (5200 meters).
79
Tasman Basin
The Tasman Basin is a diamond shaped depression bounded on the northwest by the Australian continental rise, on the northeast by the Lord Howe Rise, on the southeast by New Zealand and the
MacQuarie Rise and on the southwest by the South Tasmania Rise.
It has a maximum length of about 3300 kilometers and a maximum width of about 1200 kilometers at a depth of 4500 meters.
Although this basin has a maximum depth of about 5200 meters, it is generally shallower than the other basins considered in this study.
The earliest deep stations in this basin were taken by the DANA.
in 1929.
Later stations were taken by DISCOVERY II (1936, 1950,
1951, and 1958), the OB (1958), GASCOYNE (1960) and other unidentified ships of the Commonwealth Scientific and Industrial Organizaticn.

0
02 (mi/i) ._
I
I
I j
I
4.OU
I I
1
2
I
I
4.0
hl.IU
I
I
I
-4
1
5.0
I.OU
I
I
1
I
I
6.0
4i.'J
'
I
I
4
6
-
DIAMANTINA 21 - 340 59'S. 102° 42'E.
x DIAMANTINA 84 - 40° 7'S. 134° 11'E.
02 oe
-I
I
I I I
I
I I I I
I I
I
I
I
I
I I I I I I
I I
I I
Figure 34. Deep sigma-O and oxygen profiles, South Australian Basin.
7.0
O
'U
-

Data were made available by this organization for a series of 17 stations taken near 34° S. and 153° F. between 1962 and 1965.
No stations extend as deep as 5000 meters.
Only one deep station was available for this basin south of 46° S.
This station shows no deep temperature minimum; however, its maximum depth is only 4380 meters.
A comparison of this station with those farther north suggests that a rise extending from northwest to southeast between about
440 and 460 S. separates the water into two separate depressions below about 4000 meters.
The minimum temperature is near the bottom and ranges between about 0. 90 and 1.
000 C. in the southern depression.
Although not observed at all stations, the deep temperature minimum appears to be present throughout the deeper parts of the northern depression. This minimum temperature ranges from about 1.
10
C. in the southeast to about 1. 2° C. in the extreme north end of the depression.
The bottom salinity is very near 34. 72%o throughout this basin, probably slightly less in the south and slightly more in the northern end.
Above about 4000 meters, the salinity increases with height to a maximum of about 34. 73%c near a depth of 2900 meters.
The bottom salinity is greater than that in any of the surrounding basins.
This is a result of the shallower depth of the basin and progressive downward mixing ofthe higher salinity water. Representative temperature and salinity profiles are shown in Figure 35.

0
2
0
-
I
I
I
I
34.50
1 flfl
I
I
I
I I
1
I
34.60
1 !O
I
I
I
34.70
2.0
I
I
34.80
2.50
I I I I
34.90
3.00
I
-
CSIRO Station G 2/54/62 x
0 DISCOVERY II
340
1'S. 153°
1683 - 46° 59'S. 155° 39'E.
5'E. (Depth: 4837m)
(Depth: 4961m)
I I
I I t I
I
I I I I
I
I
I I I
I I I
-I
I
I
I I
I I I I
I
FIgure
35.
Deep temperature (in situ) and salinity profiles, Tasman Basin.
I
I
I I I
-

The potential density below the temperature minimum is nearly constant at about 1. 02785, decreasing rather sharply upward, particularly above 3500 meters. Observations of the dissolved oxygen near the bottom range from 3. 15 to 4. 64 ml/l; however, it is believed that the oxygen content actually ranges more narrowly around 4. 50 ml/l.
Profiles of o and dissolved oxygen are shown in Figure 36.
The potential temperature, salinity, and oxygen near the bottom in this basin are nearly the same as those at about 4000 meters in the South Australian Basin.
Southwest Pacific Basin
This spacious, angular basin extends from 15° to 610
S.
latitude and from 130° W. to 164° F. longitude. Its maximum dimensions are 3200 by 5000 kilometers at a depth of 4500 meters.
The Southwest Pacific Basin is bounded on the west by the Friendly and
Kermadec Islands and the ridges and plateaus associated with these islands and New Zealand.
The Albatross Cordillera forms its eastern and southern boundaries; the Cook Islands, Tuamotu Archipelago andAustral Seamount Chain interrupt its northward extension into the Central Pacific Basin. The bottom water is presumed to enter the Pacific through the passage between New Zealand and the
Antarctic continent (Sverdrup, Johnson and Fleming, 1942).
The

0
_________
'
I I
1
3.0
E;I
I
4.0
I
I
I
5.0
g.uu
6.0
...
I I
I
0.
4
-
-
6
02 x CSIRO Station G 3/62/65 -
0 DISCOVERY II
340 1'S. 153° 5'E.
-I
I I I I I
I
I
I
I I I 1 I I I I
I
I I I I
I
Figure 36. Deep sigma-e and oxygen profiles, Tasman Basin.
I
-
-
7.0

earliest deep stations i.n this area were taken by the CARNEGIE
(1929) and the DANA (1928).
A large number of deep stations were taken by
DISCOVERY II (1932, 1938, 1950 and 1951).
Other deep stations in this area have been taken by the GALATHEA (1952), the
HORIZON (1957), the VITYAZ (1957 and 1958), the OB (1958), the
GASCOYNE (1961) and the ARGO (1961).
The deep temperature minimum is well documented in the western part of the Southwest Pacific Basin (Figure 37).
Stations in the eastern part of the basin are generally too shallow to substantiate its existence there; however, there is a strong indication of such in the temperature profile of the most southeasterly station in this area (DISCOVERY II, station 964). The depth of the minimum is between 4500 and 4800 meters.
Horizontally, the temperature increases from west to east, ranging from just under 0.
60 C. to just over 1.
30
C., with little rorthsouth gradient (Plate II).
The deep salinity measurements in this basin show considerable scatter, so that only the gross features of this parameter can be discerned. Although reported salinities below 4500 meters range from 34. 59 to 34. 76%o, the actual range is undoubtedly much narrower than this.
The mean of all observed values at these depths is
34. 696%o, and it is concluded that the saiirAty ranges between about
34. 69 and 34. 7l%o, with the lower values in the southwestern part of the basin (Plate V). The associated potential density is calculated

0
T(°C)
1
14
4
6
7
T
S
VITYAZ 3812 - 14 49'S. 172° 56'W.
x DISCOVERY II 964 - 49° 42'S. 135°33'W.(Depth: 4734m)
0 ARGO 25 - 54° 31.5'S. 177° 10'W.
(Depth: 7203m)
(Depth: 5302m)
Figure 37. Deep temperature (in situ) and salinity profiles, Southwest Pacific Basin.

to range between about 27. 855 in the southwest and 27. 845 in the eastern end of the basin. Except in the deeper part of the Tonga. and
Kérmadec trenches, the potential density shows a rather sharp increase all the way to the bottom.
Near the bottom the dissolved oxygen content is between 4. 60 and 4. 8 ml/l (Figure 38) except in the eastern part of the basin where it decreases somewhat.
The older DISCOVERY II measurements indicate that it falls as low as 3. 70 ml/l; however, a more recent determination by the HORIZON gives a value of 4. 55 ml/l, which seems more probable.
Central Pacific Basin
The Central Pacific Basin is bounded by ridges associated with island chains - - on the west, the Gilbert and Marshall Islands; on the east, the Line Islands; and on the south, the Society Is lands.
On the north it is bounded by the Mid-Pacific Mountains lying between
Wake Island and the Hawaiian Islands near 20° N.
This basin is irregular in shape with a maximum dimension of 5500 kilometers in the northwest-southeast direction by about 2000 kilometers in width at a depth of 4500 meters.
There appears to be free interchange of water below about 4400 meters with evidence of a barrier b e low this depth separating the southwestern sector from the rest.
The earliest deep station from this basin which was used in this

1
02 (mi/I) _-
'
I I I I
I
I
I
4.0
27.60
I
I
I
I I I
5.0
Z7.i0
I
I
I 1 I I
6.0
z.1.0
I I
I
7.0
I
1
I
1
I
8.0
Jo
1*
0.
ni
4
02E?
6
7
-
I I I I
I
VITYAZ 3812 - 14° 49'S. 172° 56'W.
x DISCOVERY II 964 - 49° 42'S. 135° 33'W.
o ARGO 25 - 540 31.5'S. 177° 1O'W.
I
I I
I
I I I I I I
I
I
I I
Figure 38. Deep sigma-O and oxygen profiles, Southwest Pacific Basin.

study was taken by the CARNEGIE in 1929.
Subsequently, such stations have been taken by the ALBATROSS (1947), the STRANGER
(1956), the VITYAZ (1957), the ARGO (1960), the REHOBOTH (1961), the GASCOYNE (1961) and the DAVIS (1964).
Most of the stations in this basin which adequately sample the depth to 5000 meters show a temperature minimum at about 4600 to
4800 meters (Figure 39).
The temperature at this depth ranges between 1. 2 and 1. 3° C.
Below 5000 meters, the gradient steepens but remains slightly less than adiabatic at all stations, even showing signs of decreasing somewhat near the bottom at two stations
(REHOBOTH stations 5 and 16).
The temperature below 4700 meters at these two stations is about 0. 05° C. warmer than that in the southwestern part ofthe basin.
This is believed to be caused by adiabatic warming rather than geothermal heating, although the latter could not be positively ruled out on the basis of the observations at hand.
The observed salinity values in this basin are extremely vanable, ranging from 34. 69 to 34.93%°,the latter and other anomalously high values rather obviously being in error. It is concluded (somewhat arbitrarily) from the statistical distribution of observations that the actual salinity falls between 34. 70 and 34. 71%o below 4500 meters in this basin. From these values of salinity and the corresponding potential temperatures, the potential density was then computed to be about 1. 02784 below about 4700 meters. The dissolved oxygen

0
8(7,,,)
-
T(°C).
34.60
1.50
El
34.70
2.00
34.80
2.50
34.90
3.00
35.00
3.50
6
ALBATROSS 133 x REHOBOTH o REBOBOTU
50 O'N. 172° 2'W. (Depth: 5390m)
16 - 70 o'5 160° O'W.
(Depth: 5879m)
9 - 3° 48'S. 179° 55'W. (Depth: 5650m)
Figure 39. Deep temperature (in situ) and salinity profiles, Central Pacific Basin.

content below 5000 meters ranges from about 4. 5 ml/l in the southwest sector to about 4. 1 ml/l in the nortIast corner of the basin
(Figure 40).
Potential density, potential temperature, and salinity of the bottom water entering the southwest corner of this basin are almost identical with those at a depth of 4300 or 4400 meters in the northern part of the Southwest Pacific Basin (compare REHOBOTH station 9 and ARGO station 14).
It appears that this water moves downslope along the 27. 84 sigma-O surface with little modification, including only a slight decrease in dissolved oxygen content.
91
Northeast Pacific Basin
This extensive basin ranges from near the equator to the
Aleutian Trench at about 50° N. latitude. It is bounded on the east and north by the continental rise bordering the North American
Continent and the Aleutian Islands.
The broken western boundary is formed by the ridges associated with the Emperor Seamount Chain and the Hawaiian Rise in the southwest. The southeastern boundary is rather indefinitely formed by the gradually southeastward decrease in depth in the central Pacific. The basin roughly has the shape of a parallelogram with sides 3500 and 6000 kilometers in length at a depth of 4500 meters.

O2(m1fl)..
I
I
I
'
I
I
I lj
27.70
[I
I
I I
5.00
27.S0
I I
600
27,90
'
J
1
1
I
I
I
7 .00
28.1
DO
I.
3:
-
-
-
-
Ø'k02 A
ALBATROSS 133 5° O'N. 172° 2'!.
x REHOBOTH 16 - 70 0'S. 1600 0'!.
0 REBOBOTH 9
30 48'S. 179° 55'!
tI
I I I
1 I
I t
I iii I
I I I
I I
I
I
I I I i I t
I
I I
I
Figure 40. Deep slgma-e and oxygen profiles, Central Paelflc Basin.
ii
I
I I i
-
0

93
The earliest deep station in this area was taken by the DANA
(1928) followed closely by the CARNEGIE (1929).
Other deep stations were taken later by the ALBATROSS (1947), the BROWN BEAR
(1954, 1957 and 1958), the HORIZON and SPENCER F. BAIRD
(1955, 1956, 1960 and 1961), the REHOBOTH (1956, 1959, 1961 and
1963), the VITYAZ (1957-1959), the ARGO (1961), the PIONEER
(1961 amd 1962), the AGASSIZ (1963), the SURVEYOR (1963 and
1964), the DAVIS (1964-1966) and the YAQUINA (1966).
As is evident from the foregoing list of ships, the basin has been well sampled within the accuracy of existing techniques and practices.
The deep temperature minimum is documented throughout this large basin at a depth of about 3900 meters. The temperature at the minimum is between 1.45 and 1. 50° C. throughout most of the basin, falling to near 1.
350
C. south of the Hawaiian Islands, where water from the Central Pacific Basin first flows into this basin.
Example profiles (Figures 41 and 42) were selected from ten deep stations taken by the author from the YAQUINA during June of 1966.
Nansen bottles and reversing thermometers were spaced 100 meters apart near the bottom of these casts and 250 meters apart over the remainder of the deep casts. Smooth curves could be drawn to within 0.
020 C. of nearly all temperature values.
The two stations chosen as examples are the most southerly and northerly; they are representatives of the other stations of this series.
As can be seen

from these examples, the temperature gradient decreases gradually and continuously with depth to produce a sweeping broad curve through the temperature minimum where it reverses and approximates the adiabatic gradient below about 4700 to 5000 meters.
The decrease in curvature with latitude should be noted.
This largely results from the latitudinal decrease in temperature at the shallower depths.
Average temperatures, salinities, and potential densities have been computed from the values interpolated at standard depths for 13 stations taken at nearly the same location by the REHOBOTH. These stations are between 28° and 29° N. and 176° to 177° W. The resulting profiles together with the ranges are shown in Figure 43.
The temperature profile agrees well with those from the YAQUINA.
The salinity increases continuously with depth to about 4500 meters, below which it remains nearly constant between 34. 69 and
34. 70%o.
By comparison with other salinity measurements in the area, the salinities for the Hawaiian-Adak leg of the YAQUINA (1966) cruise were found to be low by about 0.
0Z%o.
The salinity profiles in Figure 41 have been adjusted by this amount. The potential density increases rather sharply to about 4500 meters, below which there is little change (Figure 42). The deep potential density ranges from about 1. 02782 to 1. 02783 in the southern part of this basin and from about 1. 02781 to 1. 02782 in the northern part. The mean oxygen

2
I..
4
6
T(°C) -
34.40
1.50
34.50
2.00
34.60
2.50
34.70
3.00
34.80
3.50
Figure 41. Deep temperature (In situ) and salinity profiles, Northeast Pacific Basin.
Ui

p1 ru
4
6
0
02 (m1/)
1
2 z..Du
Z-I.-w
.
YAQUINA H&H-23 - 26° 37.8'N. 161° 31.4'W.
YAQUINA HAH-56 - 5O 27.S'N. 176° 13.8'W.
r
Figure 42. Deep slgma-O profiles, Northeast Pacific Basin.
Z1.ft)

0
T(°C) .
I
'I
' i
27.50
34.30
2.00
'I 'I
' I '
II
I
27.60
34.40
I
I
1
I
2
-
I-
I
2.50
I
I '
I
I
27.70
34.50
I I
3.00
I i
27.80
3460
1
I
I j
27.90
i
3.50
1i 1!'
34.70
_____1__________.______1_________
I -
-
I 4
T
6 x REHOBOTH (13 casts, 1959-1961) - 28°-29°N. 176°-177°W. (Depth: 530O)
7
-I
I I I I
I
I I I I I I I I I
I
I I I I I I
I I I
I
I i I
I
I
I I I I I I I I I I I I I I
FIgure 43. Mean profiles of deep temperature (In situ), salinity and sigma-a from 13 repeated casts, Northeast Pacific Basin.
'0

below 5000 meters in this basin is about 3. 6 mi/i; at the temperature minimum the oxygen content averages about 3. 35 mi/i.
After elimination of the 10% highest and iowest values, the range in observations at the greater depths is from 3. 35 to 3. 90 ml/i.
The dissoived oxygen content is slightly iower in the central part of the basin; however, the horizontal variation is small.
Northwest Pacific and Mariana Basins
Inasmuch as the deep water in the Northwest Pacific Basin has essentially the same characteristics as that in the Mariana Basin, these two basins are discussed together, even though they are partially separated by the Mid-Pacific Mountains.
These basins are bounded by rises associated with the Emperor Seamount Chain on the east and with Kamchatka, the Kuril Islands, Japan, and the
Mariana Islands on the west, These rises converge northward forming an apex southwest of the Komandorskiye Ostrova, which separates the Kuril and Aleutian trenches. The Mariana Basin is bounded on the south and east by the islands and associated rises of
Micronesia. These combined basins are roughly in the shape of an arrowhead with a length of about 5200 kilometers and a width of about 4000 kilometers at a depth of 4500 meters,
The earliest deep stations available for this area were taken by the CARNEGIE in 1929.
Ships of the Japan Maritime Safety Board

took several deep stations in the l930's and again in the late 1950's and early l960s.
Ships of the Japan Meteorological Agency took several deep stations in the Northwest Pacific Basin in 1960 and 1961.
Deep stations have also been taken by the VITYA.Z (1957 and 1959), the REHOBOTH (1958 through 1963), the SPENCER F. BAIRD (1962), the BERING STRAIT (1964) and the DAVIS (1964).
The deep temperature minimum is found throughout these basins except in the southeast corner where the water appears to enter from the Central Pacific Basii.
As illustrated in Figure 44 the temperature profiles are represented by broad sweeping curves below 2000 meters.
4000 and 4500 meters.
The temperature minimum is found between
Below 5500 meters the vertical temperature gradient is generally adiabatic. The horizontal temperature gradient is very flat throughout these basins with the coldest water of slightly less than 1. 40° C. entering from the Central Pacific Basin to the
Southeast.
The highest deep minimum temperature is about 1. 55° C.
The bottom salinity varies from just less than 34. 69%o in the Kuril,
Japan, and Mariana trenches to about 34.
70%o in the south central and southeastern part of the basin. The salinity decreases upward and is as much as 0. 01 to 0. O2%o less at the depth of the temperature minimum than it is at the bottom. Because of the great variability in the salinity observations, attributed largely to measurement error, profiles (Figure 44) are averages for several stations.
The

T(°C) -
I 'I' I 'I
34.40
1.50
j
I I
I
34.50
2.00
I
I
I
I
I
I
I
I
34.60
2.50
I I
I
I
I
TI
34.70
3.00
I
'
I I ' I I
I
34.8r!
3.50
2
-
0 x
6
-
-
0\\x
T'%
S
REHOBOrE (8 casts, 1958-1960) 18°-20°N. 186°L x BERING STRAIT (3 casts, 1964) - '-.34° 5'N. 164° 30'E. (Depth: 5850m)
0 REHOBOTH (7 casts, 1961-1963) - - 52°N. 161°E.
(Depth: 5320n)
(Depth: 6-7000a)
I I I I I I i I i 1 i I I I I I i
I i
I
I I i I I I i
I
I I i I I
I
I I I
I I I
Figure 44. Mean profiles of deep temperature and salinity, Northwest Pacific Basin.
C

101 possibility that some of these differences reflect temporal variations cannot be entirely discounted; however, the vertical density gradient does not support arguments in favor of such large variations.
The bottom potential density ranges from less than 1. 02781 in northern end of the Kuril Trench to over 1. 02782 in the south central and southeast sector of this basin complex. The potential density decreases continuously with height above the bottom (Figure 45).
Reported observations of dissolved oxygen content near the bottom range from 2. 91 to 5. 11 ml/l; however, the range is probably much narrower, probably between about 3. 5 and 4. 0 ml/l.
The oxygen content appears to increase downward below the minimum between 500 and 1500 meters all the way to the bottom (Figure 46).
Even though there is a rather large number of deep observations in these basins, the accuracy of many is questionable, particularly regarding the salinity values; thus, the confi4ence level in the values derived for these basins is not high.
Additional, carefully controlled measurements are needed.
Philippine Basin
The Philippine Basin lies between the Ryukyu and Philippine
Islands on the west and the Mariana and Volcano Islands on the east.
The ridges of these island chains converge to the north and south forming a diamond.-shaped basin about 2000 kilometers in length

1
02 (uui1/1)
I
I I I
I
II
I I I I
I
Ij
II
Ii 'I' liii
Z7.
90
S
7
6
-
-
-
-
0 x
REHOBOTH (8 x BERING STRAIT (3
0 REHOBOTH (7 casts, 1958-1960) casts, 1964) - -
18°-20°N. 166°E.
340 5'N. 164° 30'E.
casts, 1961-1963) - - 52°N. 161°E.
0
0
I
I I
I
I
I I ii ii
Figure 45. Mean profiles of deep
I
I
I slgmaliii
Ii
Northwest Pacific Basin.
I!
I
I
I
-
-
-
-
0

04
4
6
7
0
1
Figure 46. Deep oxygen profiles, Northwest Pacific Basin.
0
(J

104 and 1600 kilometers across.
The first deep stations available for this area were taken by the
PLANET (1922-1924); however, each of these three stations (one in each year) sampled only one level (the bottom) deeper than 1000 meters.
The SNELLIUS obtained several deep stations in this area in 1929 and 1930.
Ships of the Japan Hydrographic Department and the Japan Maritime Safety Board took deep stations in the 1930Ts.
Ships of the latter took one deep stations here in 1959.
Other deep stations have been taken by the ALBATROSS (1948), the GALA.THEA
(1951), the VITYAZ (1957), the SPENCER F. BAIRD (1962), ai the
DAVIS (1964).
A temperature minimum is found throughout the basin at a depth of about 4000 meters. The temperature at the minimum ranges between about 1. 5 and 1. 6° C.
Thus, there is only a slight horizontal gradient within this basin at this level. Below the temperature minimum, the gradient steepens quickly and appears to be adiabatic throughout most of the basin below about 5000 meters (Figure 47).
Near the bottom the salinity is about 34, 69%.
It decreases very gradually with height above the bottom (Figure 46) and shows no clear pattern of change horizontally within the basin.
The potential density is nearly constant at about 1. 02780 below 5000 meters, decreasing with height above that depth (Figure 47).
The dissolved oxygen content shows little change with depth below 4000 meters but

0
T(°C)--
34.60
1.50
I11111111!I
1
2
I I
34.70
2.00
It I jT
34.80
2.50
34.90
3.00
1111(11 11111!
liii
I
II
35.00
3.50
gi
4
6 x VITYAZ
3746 -
190
15'N. 134° 15'E.
(Depth: 5827w) i
I i
I i
I I
I
I I
I I I
I I
I
I I
I
I
I
I
I I
Figure 47. Deep temperature (In situ) and salinity profiles, Philippine Basin.
0
U.'

decreases rather rapidly with height above that depth (Figure 48).
Near the bottom it probably ranges between about 3. 3 and 3. 6 ml/l although the reported values show a much greater range than this.
106

1
2
02 (mi/i) __ 1.0
27.60
2.0
27.70
3.0
27.80
4.0
27.90
4
6
-
7 z VITYAZ
002
3746 - 19° 15'N. 134° 15'E.
-1 I i
1 i
I
I
I t I i I
I
I I I
I
I
I I i I
I I I i
I
Figure 48. Deep sigma-e and oxygen profiles, Philippine Basin.
I I I
-
5.0
28.
00
C

III.
DISCUSSION AND CONCLUSIONS
It is rather tempting to attribute the near bottom curvature of the in situ temperature profiles to geothermal heating; however, except in the trenches and the more stagnant deep basins, the evidence of geothermal heat flow in the circulation of the bottom water is over-shadowed by other processes.
1) adiabatic warming accompanying downslope flow; 2) mixing and advection approximately along constant potential density surfaces; and 3) vertical eddy flux of heat and salt.
Adiabatic processes are those which take place without loss or gain of heat or, more precisely, without change in entropy.
sure and temperature relationships for such processes in ideal fluids are derived by expressing the total change in entropy by partial derivatives and setting the sum of these equal to zero. The derived equation is:
C p avT p where: F = entropy; T = temperature; P = pressure; v = specific volume; a coefficient of isopiestic thermal expansion; and
C p
= isopiestic heat constant.
In order to eliminate temperature changes due to adiabatic heating,it is convenient to introduce the potential temperature, 0.
The

109 potential temperature is the temperature water would have if it were decompressed adiabatically to a pressure of one atmosphere.
Using the new values for the specific heat of seawater at atmospheric pressure determined by Cox and Smith (1959) and Fkman's
(1908) data on the compressibility of seawater, Crease and Catton
(1961) have prepared new tables of the adiabatic cooling of seawater.
These tables or an equation derived from them have been used in adiabatic computations in this study.
The following polynomial expression was derived by least squares fit to the data of the tables:
AQ
= 3.49 x JO TZ + 9. 89 x x l0 T2Z2 + 9. 28 x l0 SZ
Z2 - 2. 13 Z3 + 7. 79 where:
/Q
= T - 0; T = in situ temperature (°C);
Z = depth of temperature measurement (kilometers);
S = salinity
(%o); and 0 = potential temperature (°C).
A super-adiabatic temperature gradient accompanied by constant salinity does not indicate absolute instability but rather potential instability released by vertical, adiabatic displacement of the parcel under consideration.
Critical instability, which is associated with an autoconvective lapse rate (terms used in meteorology) is a condition in which the in situ density decreases with depth (pressure).
Expressed in terms of specific volume, the limiting case for critical instability is 0.
By partial differentiation of the specific

volume (v) with respect to temperature (T) and pressure (P) and introduction of the known coefficients of isothermal compressibility and isopiestic thermal expansion through Maxwell's equations, this lapse rate is found to be about 5.
50 c/loo meters. In contrast, the adiabatic lapse rate doesnt exceed 0. 2° C/bOO meters in the deep ocean basins.
The important point here is that, even with constant salinity, lapse rates between the adiabatic and autoconvective are unstable only in the presence of vertical displacements. Such lapse rates might be expected in the absence of vertical motion where bottom heating is present. They are found in the lower atmosphere under special conditions and are thought to give rise to dust devils
(Byers, 1944).
Adiabatic processes are illustrated in Figure 49.
From the example shown, it can be seen that where the lapse rate is subadiabatic, mixing causes a transfer of heat downward.
Mixing or overturning of a layer of water having a superadiabatic lapse rate transfers heat upward.
Molecular conduction takes place without displacement of the molecules to levels of higher or lower pressure; thus, molecular conduction is a function of the in situ rather than the potential temperature gradient. In the case of eddy conduction, the displacement of the interacting parcels is finite. That conductive heat
110

ii
Ad.iaba.ts
U t
I
-
- -
0
LEVELS\
A \
- B
\
\
- - -
LAPSE RATE
Sub-adiabatic
-
- -
-
\
Adiabatic
\
- C
I
Super adiabatic I
- D
- -
\
\
T
DISPLACNT
From A to B
From B to A
From B to C or C to B
From C to D
From D to C
RESULTS
Particle is warmer than its surroundings; particle gives up heat (cools).
Particle 18 colder than its surroundings; particle absorbs heat (warms).
Particle is the same temperature as its surroundings for either displacement.
Particle is colder than its surroundings; particle absorba heat (warms).
Particle is warmer than its surroundings; particle gives up heat (cools).
Figure 9.
Adiabatic processes.
I-

112 transfer (molecular) in the ocean is not significant can be seen from the following example.
Since the thermal conductivity of sea water is about 1. 45 x cal/°C cm sec at 6000 meters, to remove the geothermal heat from the sea floor by conduction would require a temperature gradient of about 1000 C/km.
In summary then, for a condition of constant salinity the adiabatic lapse rate is the boundary condition between upward and downward heat transfer by eddy conduction and overturning, whereas the in situ temperature minimum (or maximum) is the boundary between upward and downward molecular conduction. Eddy conduction and overturning will convey heat downward above level B and upward below level C in the example.
If these are the only processes operating, geothermal heat can be carried upward only along superadiabatic paths.
Although superadiabatic gradients must exist at the bottom in order for geothermal heat to flow out of the sediments, verification of such gradients is difficult with present measurement capabilities.
Kuenen (1942) concluded that the temperature gradient in the depths of the Celebes Sea and elsewhere was less than adiabatic; however the adiabatic tables of Ekman (1914) in use at that time gave somewhat larger adiabatic gradients than the newer tables of Crease and
Catton (1961).
Many of the deep temperature measurements yield gradients greater than the adiabatic, but the majority of these are

113 greater by less than the probable error of measurement.
In an effort to detect such superadiabatic gradients, data from the
1966 YA.LOC
cruise of the YAQIJINA have been averaged.
For these measurements thermometers were spaced at 100 meter intervals near the bottom and at 250 meters above 300 or 400 meters.
Great care was taken in reading the thermometers. Gradients were computed at reasonable intervals below 4000 meters and plotted against a curve of adiabatic gradients constructed from the tables of Crease and
Catton (1961).
The results, shown in Figure 50, indicate superadiabatic gradients below
5500 meters; however, because of the small number of observations at the greater depths, this cannot be considered conclusive. There are undoubtedly temporal variations in such gradients but the magnitude and time scale of these cannot be determined from the limited number of suitable measurements available.
Many more such observations are needed, including thermograd measurements with good depth indicators.
Another conservative property which takes into account differences in salinity is the potential density. This is the density that a parcel of water would have if it were decompressed adiabatically to a pressure of one atmosphere (Wust,
1933).
As previously mentioned, Hesselberg and Sverdrup
(1915) pointed out that the p0tential density only indicates qualitatively whether the equilibrium is positive, negative, or indifferent in the absence of a vertical

2
0.05
TEMPERATURE GRADIENT (°C/km)
0.10
0.15
10
9 I
8
[1
3
7
8
® Means for YAQUINA-HAH stations
(Numerals give number of measuremen
10 and 20 curves based on tables by
Crease and Catton (1961).
Figure 50. Potential temperature gradient vs depth.
114

salinity gradient. Because of the variation of the compressibility of water with temperature and, to a lesser extent, with salinity, the equilibrium of a water column is not reflected in the potential density distribution in the presence of vertical salinity gradients.
In place of the potential density, Hesselberg and Sverdrup (19 15) proposed the use of a stability function (F) given by the following equation:
F dZ
L\
+ as dZ
-
115 where: Z = depth in meters (positive downward)
S = salinity in %
T = temperature in 0C.
d p = density
= the adiabatic lapse rate in potential temperature in °C.
C/meter
Hesselberg and Sverdrup provide tables for obtaining values of and as functions of depth, temperature and salinity.
Using these and gradients measured at depths of interest from temperature and salinity profiles, the stability parameter, F, can be computed.
This was done by Schubert (1935) for several stations in the Atlantic and has been done in this study for near-bottom portions of selected profiles in the major deep basins. The results are shown in Table 2.

Table 2.
Basin
Atlantic-Indian
South Indian
Southeast Pacific
Argentine
Brazil
North American
Sierra Leone
Canary and Iberian
Angola
Cape
Natal
Crozet
Madagascar-Mascarene
Somali
Mid-Indian
Wharton
South Australian
Tasman
Southwest Pacific
Central Pacific
Northeast Pacific
Northwest Pacific
Philippine
5000
4500
5000
5500
5000
5000
5000
5500
5000
5000
5000
4700
5000
5000
4800
5000
6000
4500
5000
5500
5-7000
5-6000
5000
F x 10 8
0. 5
7. 0
-1.0 to 2.0
5. 0
3.0 to 10.0
0 to 4. 0
3.0
0. 5
-0. 5
3. 5
5.0
3.0 to 11.0
5.5
1.0
-1. 5
0.0
0. 0
2.0
0. 5 to 1. 5
1.0
0. 0 to -0. 5
0. 0 to 2. 0
1. 0
116

117
In addition, F values have been computed for several depths below
2500 meters for CRAWFORD station 1364 in the Brazil Basin (Table
3) in order to show that this water is in stable equilibrium even though the potential density distribution suggests otherwise.
Values of the stability function, F, (Table 2) also show that the near-bottom water in the basins of the North Atlantic Ocean is in stable equilibrium even where the potential density distribution is constant or decreases with depth. Negative values appear in this table only where the salinity is essentially constant with depth.
In order to examine the gross movement and modifications of the bottom water for the oceans as a whole salinity and oxygen values have been plotted against potential temperatures for each of the major basins (Figures 51 and 52).
It is observed that in general the potential temperature increases with distance from the Weddell
Sea.
Thus, the temperature of the bottom water in the Antarctic basins is progressively warmer proceeding from the Atlantic-Indian
Basin (A-i) eastward to the Southeast Pacific Basin (P-l).
In each of the three oceanic extensions, the bottom water is increasingly warmer with distance from the Antarctic. The warmest Antarctic
Bottom Water is found in the North Pacific (P-5, P-6 and P7) with the next warmest in the northern basins of the Indian Ocean (N-6 and N-7).
Still warmer water of Arctic origin is found in the North
Atlantic and Angola basins (A-4, A-5, A-6 and A-7).

Table 3.
Stability Function, F, at Various Depths in the Brazil Basin.
Depth (meters)
2900
3395
3892
4392
4891
5391
5740
F x 108
6. 1
8. 9
17.9
9. 1
4.6
2.5
2.8
118

J42'
0.00
TEMPERATURE (°C)
1.00
2.00
34.70
34.80
.Oo
Z 34.90
- ATLANTIC
34.65
34.70
___ INDIAN
34 70
PAC IF IC
3475
I
Figure 51.
I
I
I
Potential temperature vs Salinity, major deep ocean basins.

-S
5.0
-1.00
PO2NTIAL TN2URE (°c)
0.00
1.00
I I
Letter-number ebinations designate basins (see Plate I).
A-i
A-2
N-i
.
P-i
A-3
.N-2, N-3 , A-8
N-9.
N-8b
P-2,
N-8a. N-6
I
2.00
I
A-6
A-7
A-5b$
A-5a
P-i.
S p-6
-I
I I
Figure 52.
Dissolved oxygen vs temperature, major deep ocean basins.

121
The dissolved oxygen content shows somewhat more scatter and an inverse relationship, decreasing with increasing potential temperature and distance from the Weddell Sea and Antarctic generally.
Except in the Brazil, Angola and North Atlantic basins, the dissolved oxygen content generally increases at depth essentially all the way to the bottom.
Thus, in the Pacific, Indian and most of the South Atlantic basins there is a decrease in oxygen in the direction of flow caused by downward mixing of water with a lower oxygen content coupled with depletion by oxidation of organic material.
Processes controlling the oxygen content are more complex north of 300 S. latitude in the Atlantic Ocean.
Mean values of the dissolved oxygen content near the bottom are shown for the major deep basins in Plate VII. Oxygen values reported by DISCOVERY II in the Cape-Aguihas-Natal basin complex are significantly lower than values reported by other ships and were omitted in the computation of the mean value shown (4. 9 ml/1). By including the DISCOVERY II data, the mean oxygen content is reduced to
4. 7 ml/l.
By constructing mean profiles and horizontal gradients of oxygen, salinity and potential temperature, we can theoretically approximate the rate of flow, the rate of oxidation and the vertical mixing coefficient.
This assumes that this coefficient is constant throughout the layer considered, that it is the same for oxygen,

122 salinity and temperature, and that vertical mixing is balanced by horizontal advection and depletion (oxidation) or generation (heat flow).
This would be a very gross approximation and will not be carried out here.
It should be noted that w}reas the salinity near the bottom increases with distance from the Antarctic in the Atlantic and to a lesser degree in the Indian Ocean, it decreases northward in the
Pacific.
As previously stated, the anomalously high potential temperature, salinity and oxygen in the Angola and North Atlantic basins are associated with bottom water of an entirely different origin than that in the other basins.
The minimum volume of water that must be transported in order to remove the geothermal heat added below 4600 meters has been computed for several basins.
This was done by multiplying the area of the basin below 4600 meters by the rate of geothermal heat flow (1. 4 x 1O cal/cm2 sec) and dividing by the maximum temperature increase across the basin.
That is,
AxHT where, A = area of the basin in cm2
H = geothermal heat flow (1. 4 x 1O6 cal/cm2 sec)

123
= maximum potential temperature difference across the basin in °C.
T = transport in 12 Sverdrup (1 Sverdrup = cubic meters/s e c)
This assumes that the water enters the basin at the coldest temperature and leaves at the warmest temperature and that the only heating is through the bottom.
Downward flux of heat from above, flow paralleling the isotherms, entrance of water at a higher temperature and exit at lower temperature all increase the transport required to maintain a heat balance.
The results of these computations are given in Table 4.
In the South Atlantic the computations give a required transport ranging from 0. 05 to 0. 3 Sverdrup.
This compares with an estimated transport of bottom water of 1 to 3 Sverdrup between the equator and
30° S. latitude in the Atlantic as given by Sverdrup, Johnson and
Fleming (1942).
It is seen that in this area where the volume of transport of bottom water is best known, the proportion required to remove the geothermal heat under the conditions assumed is at least 10% of the total.
It is readily apparent from Table 4 that the largest minimum transports are found in regions where the deep temperature minimum is highest above the bottom (in the Central and Northeast
Pacific, for example). In these regions flow is sluggish and the

124 goethermal heat is transported upward through a thicker layer.
TabJe 4.
Minimum Transport Required to Remove
Geothermal Heat by Advection.
Basin
AtlanticIndian
Southeast Pacific
Argentine
Brazil
Guinea and Angola
Cape and Agulhas
Mid.Indian
Wharton
Southwest Pacific
Central Pacific
Northeast Pacific
Area
(1016 cm2)
5. 2
14. 0
8. 1
4. 1
3. 6
3. 3
5. 9
3. 8
3. 1
3. 1
18. 0
Transport
(Sverdrup)
0. 3
0. 1
0. 1
0. 1
0. 3
0. 1
0. 2
0. 2
0. 3
0. 8
1. 3
It is evident that from existing measurements of temperature and salinity only general conclusions can be drawn concerning the part that geothermal heat flow plays in the abyssal circulation.
Spacing of bottles and thermometers in most deep casts is generally too great to determine the vertical temperature distribution with the precision required.
Closer spacing of bottles and the use of thermograd

recorders with depth indicators are required to document the small
125 but significant temperature variations found in the deep basins.
Errors in tne determinations of salinity and dissolved oxygen content must be substantially reduced, if temporal fluctuations in these properties at great depths are to be studied.
Substantial improvements are possible by consistent use of rigorous techniques now available.

126
IV.
BIBLIOGRAPHY
Anderson, E. R.
report 1252)
1964.
Single-depth charts of the world's ocean
San Diego.
90 charts.
Brennecke, Wilhelm.
1921.
Die ozeanographischen Arbeiten der
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Deutschen Sweewarte. Vol. 39.
In:
Hamburg, Hammerich and
Lesser.
216 p.
Buchanan, J.
Y.
1888.
The exploration of the Gulf of Guinea.
1956.
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259 p.
(English translation by Nina A. Stepanova, U. S. Weather
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Byers, Horace R.
1944.
General meteorology.
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645 p.
Cox, R. A. and N. D. Smith.
1959.
The specific heat of sea water.
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1961.
Tables of adiabatic cooling of
11
A 15)
Deacon, C. F. R 1933.
South Atlantic Ocean.
Discovery Reports 7:l71-38.
1937.
The hydrology of the Southern Ocean.
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1961.
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729 p.
Vol.
1.
New York,
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1957.
in die Oceanographie.
Berlin, Gebruder Borntraeger.
492 p.

127
Drygaiski, Erich von.
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Heft 5.
Berlin, Instituts fur Meerskunde und des
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181 p.
Eckart, Carl.
pressures.
1958.
Properties of water, part II.
The equation
American Journal of Science 256:225-240.
Ekman, V. W.
1908.
Die Zusammendrueckbarkeit des Meerwassers de Circonstance du Cons eil Permanent International pour
(U. S. Naval Oceanographic
Office.
Meere.
Translation 334.
1966.
43 p.
42(6):340-344.
330. 1966.
1914.
Der adiabatische Temperaturgradient in
Annalen der Hydrographie and Maritimen Meteorologie
(U. S. Naval Oceanographic Office.
Translation
Fox, Charles J.
J..
1909.
On the coefficients of absorption of atmospheric carbonic acid in sea-water.
Transactions of
Gerard, Robert, Marcus G. Langseth, Jr. and Maurice Ewing. 1962.
Gordon, Arnold L.
1966.
Research 13:1125-1138.
Potential temperature, oxygen and
Deep-Sea
Gordon, Arnold L., Paul J. Grim and Marcus Langseth.
1966.
Layer of abnormally cold bottom water over southern Ayes
Ridge.
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Hesselberg, Th. and H. U. Sverdrup.
1915.
Die Stabilitatsver-
15, 1-16.
p
Jacobs, Stanley 5.
2 vols.
1965 and 1966.
Physical and chemical oceanono. l-CU-l-66 on NSF Grant GA-305).
Technical report

128
Knudsen, M.
1901.
Gad.
63 p.
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Kuenen, Ph. H.
In:
1942.
van Riel.
Vol.
268 p.
Collecting of samples and some general
5, part 3, section 1.
Brill.
Langseth, M. G., X. LePichon and M. Ewing.
1966.
Heat flow through the Atlantic floor and convection cells. Journal of Geophysical Research 7l(22):532l-5355.
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In:
(American Geophysical Union.
no.
8).
1965.
Review of heat flow
Washington, D. C. p. 87-190.
LePichon, Xavier.
tory) n. d.
Exit Antarctic bottom current through the Rio Grande Rise. (In press, Lamont Geological Observa-
Metcalf, W. G.
1961.
Chain-17 in the Romanche Trench.
Oceanus
8(l):Z-7.
Mosby, Hakon.
1934.
The waters of the Atlantic Antarctic Ocean.
Oslo, Kommisjon Hos Jacob Dybwad.
117 p.
Potsma, H.
1958.
Chemical results and a survey of water masses
In: of the East Indian Archipelago 1929-1930 under leadership of
P. M. van Riel.
J.
Vol.
Brill.
2,
64 p.
Oceanographic results, part 8.
Revelle, Roger and Arthur E. Maxwell.
1952.
Heat flow through the floor of the eastern North Pacific Ocean.
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Schott, Gerhard.
1905.
Die Bodenformen und Bodentemperaturen
Justus Perthes Geographischen Anstalt 51:241-247.
Schubert, 0.
V.
1935.
Die Stabilitatsverhaltnisse des Atlantischen
Ozeans.
In: Meteor reports, Band 6, Teil 2, Lieferung 1.
Berlin, Walter de Gruyter and Co.
54 p.

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Sverdrup, H. U., Martin W. Johnson and Richard H. Fleming.
1942.
New York, Prentice-Hall, Inc.
1087 p.
Taylor, P. and M. Langseth.
in the Indian Ocean.
d.
(In press, Lamont Geological Observatory)
Tydeman, G. F.
Leiden, E. J.
1922.
Brill.
Opmerkingen betreffende de temperatuur p.
102-124.
Von Herzen, R. P. and M. G. Langseth.
In:
1965.
Present status of
Vol. 6.
London,
Pergamon Press.
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365-40 7.
Wooster, Warren S. and Gordon H. Volkmann.
1960.
Indications of deep Pacific circulation from the distribution of properties at 5 kilometers. Journal of Geophysical Research 65(4):1239-
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Der Ursprung der Atlantischen Tiefenwasser.
zur Hundertjarfeier der Gesellschaft, p.
506-534.
1933.
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107 p.
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New York,
Columbia University Press.
201 p.

APPENDICES

130
APPENDIX A
SOURCES OF OCEANOGRAPHIC STATIONS
(Cruise numbers are those of the National Oceanographic Data Center unless prefaced by letter abbreviation of the ship's name.
Station available, the station number assigned by the National Oceanographic
Data Center appears in parenthesis.)
Cruise Stations Basin and ShiD
(A-i) Atlantic-Indian Basin
DEUTSCHLAND
DISCOVERY II
060044
740038
ELTANIN
OB
74039
74040
EL-8
90004
90029
116 and 117
852, 853, 858, 1147,
1148, and 1158
1363, 1539, 1547, 1549 and 1551
2014,
2318,
2541,
2594,
131,
210,
2093, 2094, 2113,
2320, 2322, 2340,
2565, 2567, 2592, and 2616
132, 144 and 145
242, 243 and 246
491
(A-la) Small basin to NW of
Atlantic-Indian Basin
ELTANIN
(A-2) Argentine Basin
CAPITAN CANEPA
FL-l2
08691
286 and 287
DEUTSCHLAND
DISCOVERY
08692
08694
060044
74035
C-344, C-345, C-348,
C-360, and C-361
230 and 246
324 and 327
94, 99, 100 and 110
D-7l, D-72, D-74 and D.-77

Basin and Shi
ELTANIN
Cruise
EL-8
EL-9
06004
Stations
121
166, 168 and 170
51,
54, 56, 57 and 58
(A-.3)
METEOR
Brazil Basin
ALBATROSS
ATLANTIS
CHAIN
CRAWFORD
L OMONOSOV
METEOR
JOHNE. PILLSBURY
SAN PABLO
(A-4) North American Basin
ALBATROSS
ATLANTIS
770418 337
310837 5777, 5779, 5789, 5781 and 5846
31035 341
310583 110, 111, 112, 113, 114,
115, 116, 128, 129, and
130
31831
31993
425, 426, 427, 428, 429,
432 and 482
1358, 1360, 1362, 1363,
1364, 1365, 1367, 1368,
90008
06004
31996
31065
1374, 1430, 1431, 1432,
1433 and 1434
380
156 and 171
30, 36, 37 and 38
(51) and 84
770418 367
310302 1581,
2639(c),
4755
2639(a), 2639(b),
2809, 4750 and
310566 5205,
5209,
5221,
5310,
5338,
5362
5206, 5207, 5208,
5217, 5219, 5220,
5261, 5308, 5309,
5315, 5317, 5319,
5359, 5360, 5361, and 5363
131

Basin and Ship
CRAWFORD
DANA
DISCOVERY II
EXPLORER
GILLIS
HORIZON
KRUZENSHTERN
LOMONOSOV
ALBERT J. MEYER
132
Cruise Stations
310974 147, 149, 151, 152, 153,
154, 155, 156, 157, 158,
159, 160, 161, 162, 163,
164, 165, 166, 167, 168,
169, 170, 171, 189, 191,
192, 193, 194, 195, 196,
198, 199, 200, 201
202 and
31209 449
310583 73 and 74
310623 226, 228,
31596
31185
31622
304 and 311
310816 325, 373,
310974 and 385
821, 837, 838, 840, 858,
860, 861, 862, 863, 864,
868 and 889
260008
740622
1356 and 1357
3611, 3612, 3613, 3614,
3620, 3621, 3622 and
3625
31098
31195
E32, £33,
E24, E28, and £35
36 and 47
60 and 61
NC2, NC3 and NC4
4 and 5
31183 10
90040
90014
7
435 and 443
31258 (2), (3), (4), (5), (7), (9),
(18), (19), (20), (22), (23),
(24), (25), and (27)
31260 (1), (3), (4), (8), (11),
(12), (13), (14), (15), (16),
(17), (18), (19), and (21)

Basin and Ship
PREVAIL
REQUISITE
REHOBOTH
SAN PABLO
SEDOV
133
Cruise Stations
31280 (1), (2), (3), (4), (5), (6),
(7), (8) and (9)
310037 6, 8, 11, 17,
31053
23, 24 and 25
C3, C6, Gb, C14, G15,
310001
J5, J6 and J9
8,
11, 27, 30, 31, 32,
310059 (1), (2), (3), (7), (23),
(31), (33), (39), and (48)
31061
31057
(14)
(4), (6), (7), (14), and (15)
31058 (3), (41), (43), (51), (52) and (53)
310060 (32), (48), (49), (52), (54),
(72), (83), (85), (93),
(104), (106) and (111)
310062 (32)
310068 (36) and (38)
310159 (23) and (24)
310648 (1)
310656 (5), (6), (8), (9), (10),
(11), (19), (21),
(23)
(22) and
310662 (8), (20), (21), (22), (23),
(24), (26), (27), (30), (31),
(32), (33), (34), (35), (36) and (41)
310932 (2)
310972 SP38
90036
90037
90038
19
10,. 22, 812 and 1425
7,
10, 13and 18

Basin and Ship
SHELDRAKE
THOR
(A-5a) Iberian Basin
CRAWFORD
DISCOVERY II
METEOR
MICHAEL SARS
PLANET
(A-5b) Canary Basin
ALBATROSS
ATLANTIS
CARNEGIE
CHAIN
CRAWFORD
DEUTSCHLAND
DISCOVERY II
HORIZON
LOMONOSOV
134
Cruise
31282
Stations
(8), (16), (27), (28), (29),
(30), (31), (32) and (33)
310647 (8)
310623
740596
248, 249, 250, 251 and
252
3870, 3871, 3872, 3891,
3895, 3896, 3905, 3907 and 3908
740622 3539
900961 L221
06004 283
580007 91
060049 1 and 10
770418
310837
328 and 342
5763, 5764, 5765, and
5759
310002 19
310035 347, 348 and 349
310583
310623
31993
78 and 79
289, 290, 291, 293, 294
1333, 1334, 1335, 1405
060044 39
74037
740622
699
3596, 3597, 3598, 3599,
3600, 3601, 3639, 3640 and 3641
31183
90008
21
365, 366, 369, 370, 371 and 372

Basin and Ship
METEOR
PILLSBURY
(A-6) Sierra Leone Basin
CHAIN
CRAWFORD
EXPLORER
LOMONOSOV
(A-7a) Guinea Basin
CHAIN
CRAWFORD
METEOR
MOWE
PLANET
SAN PABLO
(A-7b) Angola Basin
ATLANTIS
CRAWFORD
DISCOVERY II
GAUSS
GERONIMO
METEOR
PLANET
(A-8) Cape Basin
ATLANTIS
Cruise
90014
06004
31996 4
Stations
482
264, 265, 281, 282, 305,
306 and 307
135
310035
583
90993
31990
1142
317 and 340
157
1138
87 and 94
310035
31831
06004
06043 29
060049 21
31065 67
302, 304, 310, 311 and 312
467, 472, 473 and 476
224
31197
310583
234
94, 95, 96, 98, 143,
447, 448 and 449
145,
74037
06220
31995
D696
G106
123 and 135
06004 179 and 190
060049 30
31197
310837
232 and 233
5840, 5841 and 5842

NATA.L
(N-i) South Indian Basin
DISCOVERY II
OB
N-Z) Aguihas Basin
CAPITAN CANEPA
DISCOVERY II
(N-3)
Basin and Ship
CAPITAN CANEPA
CRAWFORD
DISCOVERY II
GAUSS
METEOR
PLANET
Natal Basin
DISCOVERY II
GA.LATHEA
NATAL
VEMA
Cruise Stations
08692
31831
219
452
74035 D87
74037 D416
740038 1167
74040 1801 and 2343
06220
06004
G26 and G104
24, 25, 75 and 76
91044 174
740038
74040
90830
884, 885 and 890
1705, 2164, 2166 and
2180
48
08692
740038
74039
74040
06049
74037
74039
74702
26014
91044
31834
248
848, 849 and 850
1569
2378, 2574 and 2625
54 and 60
D431
1567
2868
181 and ZOO
150 and 151
48
136

Basin and Ship
(N-4) Crozet Basin
ARGO
DISCOVERY II
OB
VEMA
Cruise
31184
74040
90830
31834
(N-5) Madagascar-Mascarene Basins
ATLANTIS 31197
ARGO
DISCOVERY II
VITYAZ
(N-6) Somali Basin
ALBATROSS
ARGO
ATLANTIS
31184
74040
90010
770418
31184
31269
31197
(N-7) Mid-Indian Basin
ALBATROSS
ARGO
DISCOVERY II
OB
PIONEER
SNELLItJS
VITYAZ
111
1756
129
62
Stations
217, 218 and 219
109
1758
4655
232 and 235
21 and 23
14 and 16
770418 205
31181
31184
74030
15
72 and 78
5341
90004
31201
64198
316
20, 23 and 26
90010
90034
23
4594 and 4599
5262, 5267, 5269, 5272 and 5278
137

138
Basin and Ship
(N-8a) Wharton Basin
ALBATROSS
ARGO
DANA
DIA.MANTINA
DISCOVERY
II
GALATHEA
GASCOYNE
KOYOMARtJ
OB
PIONEER
SNFLLITJS
VITYAZ
Cruise
(N-8b) West Australian Basin
DIAMANTINA 09001
09002
09003
09004
09007
09029
Stations
770418 183
31184 2,
121 and 128
260009 3813
09001
and 59
09003
09004
425, 427 and 432
143,
145, 148, 323, 329,
09029
336 and 339
48, 53, 58,
91 and 95
63, 64, 87,
09030
74702
6, 7,
33 and 35
2888, 2891, 2892 and 2893
26014
09012
09034
49703
90004
31201
64198
90010
90034
463
199 and 205
18, 19 and 22
11 and 19
309, 312 and 314
52 and 56
24, 145 and 146
4504, 4523, 4530, 4535 and 4553
5205 and 5212
121 and 131
8, 114 and 23
350, 357, 397, 438 and 441
139 and 307
8 and 48
44 and 45

139
Basin and Ship
DISCOVERY
II
GASCOYNE
VEMA
(N-9)
VITYAZ
So. Australia Basin
DIAMANTINA
(P-l) Southeast Pacific Basin
BURTON ISLAND
DISCOVERY II
Cruise
09032
09036
09038
74040
74702
09012
09034
31834
90010
09002
ELTANIN
OB
Stations
193
5, 14 and 46
90 and 121
1738 and 2149
2698
213 and 215
2, 4, 31 and 33
69
4567
21, 33, 58, 61 and 84
31650
740038
74039
10 and 12
728, 730, 731, 972, 974,
975, 988 and 990
1224, 1228, 1241, 1253,
1255, 1316, 1419, 1445,
1447, 1453, 1455, 1459,
1464 and 1469
74702 2837 and 2839
EL-b 195, 197, 221 and 225
231, 236, 238, 239,and 240
EL-13 293
EL-iS 361, 363 and 376
EL-17 411
EL-l9 441, 443, 444and445
EL-20 484
EL-Zi 507
90005 408, 409, 411 and 413

140
Basin and Ship
(P-2) Southwest Pacific Basin
ARGO
CARNEGIE
DANA
DISCOVERY
II
GALATHEA
GASCOYNE
HORIZON
OB
VITYA.Z
Cruise Stations
31181
26014
09033
11,
310002 162
260009
740038
74040
3580 and 3628
944, 947, 949, 950, 964,
965 and 966
2206, 2217, 2218 and 2219
74702
2739, 2769, 2770, 2823 and 2825
677
13, 14 and 25
242, 244, 246, 248, 250,
252 and 254
31802
90005
900862
D018
361, 363, 365, 381, 389,
393 and 396
3812, 3818, 3823, 3827 and 3831
(P-3) Tasman Basin
CSIRO Cruises 09785
DA.NA
DISCOVERY
GASCOYNE
OB
(P-4) Central Pacific Basin
ALBATROSS
ARGO
CARNEGIE
260009
74040
74702
09005
90005
182 and 193
17 casts at station G
(from CSIRO list)
3656, 3663 and 3665
1683
2715, 2726, 2817, 2819, and 2820
2 and 91
347, 349, 350 and 351
770418
31181
105, 128, 133 and 138
MONN
310002 159

141
Basin and Ship
DAVIS
GASCOYNE
REHOBOTH
STRANGER
Cruise
31203
09033
31884
31724
900862
Stations
9
217 and 222
5, 6, 8, 9 and 16
17 and 28
3795 and 3805 VITYAZ
(P-5) Philippine Basin
ALBATROSS 770418 162
DAVIS
GALATHEA
31203
26014
12
412, 433, 440 and 449
JAPAN MARITIME
SAFETY BOARD SHIPS 490003 61
490004 33
490005 24
490037 T18
JAPAN HYDROGRAPHIC
DEPARTMENT
PLANET
SNELLItJS
490002 OLA7
060049
64198
276, 293 and 296
47, 76, 260, 261, 264,
275 and 301
SPENCER F. BAIRD
VITYAZ
31182
900861
H14
3707, 3726, 3728, 3746 and 3759
(P-6) Northwest Pacific Basin
BERING STRAIT 31267
31397
6
26 and 62
CARNEGIE
DAVIS
310002
31203
15, 116 and 117
10, 41, 47 and 49
JAPAN MARITIME
SAFETY BOARD SHIPS 490036
490037
490003
T96, T99 and T100
TiOl
15, 18, 28, 31, 35, 38,
83, B77 and B84
68,

142
Basin and Ship Cruise
490004
Stations
30, 37, 46, 51, 78, 92 and 143
490005 94
JAPAN METEOR-
OLOGICAL AGENCY
SHIPS
REHOBOTH
490327
49330
310156
31161
31165
31180
1358, 1360, 1361 and 1362
1506, 1507, 1509, 1510 and 1511
(6), (7), (13), (14), (20),
(22), (34), and (35)
(23) and (24)
(15)
17, 21, 22, 27,
30, 35,
310617
310661
SPENCER F. BAIRD 31182
VITYAZ 900589
900861
(30) and (77)
(19), (21), (22), (23),
(31) and (37)
H4 and H92
4343, 4355, 4369, 4371,
4373 and 4377
3625, 3631, 3634, 3686 and 3689
(P-7) Northeast Pacific Basin
AGASSIZ
ALBATROSS
ARGO
BROWN BEAR
CARNEGIE
31418 60180 and 80200
770418 80,
31181
87, 93 and 123
21 and 29
31493
31558
31576
6426
14 and 21
1, 8, 10, 15 and 24
310002
DANA 260009 3563

Basin and Ship
DAVIS
HORIZON/SPENCER
F. BAIRD
PIONEER
REHOBOTH
SURVEYOR
VITYAZ
143
Cruise
31203
31589
31929
4,
7
3
Stations
5, 52 and 53
31802
31346
31099
D9, D10, MiD, M4D, and M1OD
7306 and 821234
P72, P75, P91, P94 and P97
31172
310945
31052
120
P11, P12, P13, P14,
54 and 63
H4, H5, HiS and H23
31063
31161
(38)
(17 and (40)
310617 (3), (5), (6), (55), (56),
(57), (59), (60), (61), (62),
(74), (75), (76), (78), (88) and (89)
310641
31665
31685
31884
(11), (12), (39), (40), (42),
(47) and (49)
(4) and (8)
(3), (18), (22), (23), (24)
24
31172
31204
900589
S5 and S19
37, 41, 44, 46, 49, 50,
53 and 54
4066, 4096, 4120, 4199,
4239, 4249, 4289, 4295,
4311, and 4320
900862 3778

Basin and Ship
YAQUINA
Cruise
YALOC
Stations
HAH23, HAHZ8, HAH3O,
HAH33, HAH34, HAH37,
HAH5Z, HAH54, HAHS6, and HAH57
144

APPENDIX B
PLATES

145
70
0900 105° 120° 135° 150° 155°(
9°
$50 1500 135° 120° 105° .00e
750 60° 450 30° 15°W 0° 15°E.
30° 45° 10° 750
900700
60° 600
I
45°
300
15°N
00
15°S
BASIN
30°--(N_8)
(b)
450
-
14 ttLIPPINE
BASIN
5)
N(THWEST
PACIFIC
BASIN
(p_6)
NT1tEAST
CENTRAl
PACIFIC
PACIFIC
' BASIN
(P-7)
I
** -t--* j
AS
*
SOUTHWEST crpic
BASIN
(P-2)
0
°
700
900
1050 1200 1350
1
1500 165°E 180° 165°W 150° 135°
*
-
I
*
I
1
---4*rn-
SOUTHEAST
PACIFICBASfl'1
(P-i)
*
4
(A- b)
-----
-
NTJ{
ArTCAN
BASIN
4 and
CANARY
BASIS>
(A-5) a)
-
r
I
A
A-3)
GtJINEA.
ANGOLA(-
-
*
AEGENTI
SI
I
I
I
-.
.
-
APE
BASIN
(A-8)
(N2
F
4
AS wrAxI
BASIN
C1OZ1
-
BASIN
EN--
\
-D
I
A-1aJ
,
ATlANTIC-INDIAN BASIN
(A-i)
120° 105° 90° 75° 600 45° 30° 15°W 0° 15°E
I
300 450
I
60°
-
15°
15°N
00
45e
900
10° a
PLATE I.
Major deep basins of the world oceans,

o90 105° 120°
1350
150° 165°E 180° 165°W
150° 135° 120° 105° 90° 15° 60° 45° 30° 15°W 00 15°E 30° 45° 600
75°
146
900
990 60°
-
..
150
I 4,
\
450 600
020
.
150
450
50
1.50
300 1
15°N
I
-
0
O
15°S\
> 1 15
S
12
>115
1.10
30
1 50 1.50
to j 1 60 to
1 55
<150 150
*
'
1 40
1
1 30
1
>150
'
100
.__._.___:>-__._:. i so
\
\
/
1.40
J
450
600 o.io
00o'
\S_
0
:°°
1.20
1,10
0.25
:
:
.
4
1
070
100
900
105° 120° 135° 150° 165°E 180° 165°W
150° 135° 120°
0 30
105° 90°
040
150
2.20
L91
1,8S.1 7t
"
IJ\\
/11 \
050 /
1
060 0.70
080 oo
'
I
>240
.
600
014
)
026
1
4O oio
0.00
0.10'
1.10
450
30°
_..___..-040
15°W 0°
0.40
0
15°E 30°
0 30
)
(oo
0$0
1.60
'
--.o.s
('-,
130
30°
45°
300
15°N
0°
80°
900
0°
PLATE II.

10090°
105° 120° 135° 150° 165°E 180° 165°W
650
147
135° 120°
.
105°
900 15° r
6°
45° 30° 15°W 0° 15°E 30° 45°
I.
50° 15°
900700
600
450
30°
15°N
//
'////'
7/,
,/////.
,
// '///
::.
///
/
:
- //
-4.
-
0°
0 -;
_#,
/
-
///////
/////
15°S -
p
30°
60°
10°
900
I
'
/
/
/1
//
-.
// -
-
///
//
-
///
/77/,
/
/
//
///
:
:
//
/
///////
/7/
///////
/
/
/
///////// z/////// z//
-
/ 7'
/
_// /'
I
105°
Z1
120°
-
135° 50° 165°E 180° 165°W 150°
Deep temperature minimum observed
Adiabatic lapse rate observed
135°
PLATE iii.
120° 105° 90° 15° 60° 45° 30° 150* 0° 15°E 30° 450
Areas in which the deep temperature minimum and adiabatic lapse
been observect.
60° b
75°
30°
15°
30°
90°
70°
0

90° 105° 120° 135° 150° 16S°E 180° 165°W 150° 135° 120° 105° 00°
750
60°
450
30° 15°W 0° 15°E
300
450
50° 15° 90° l'i 8
45°
30°
30
0°
150S.\çF.
300 oi
OSOtoOS5
095
1,10
2
:
070
>110
/
I
/
I/
1
7
110
-
I,
I
7
.0
>210 z10.-___
1i70
_
I f
0
2
.l('
020
II'
*
-
/
45°
30°
0°
/
L<ioo
30
I
I
020
----H-'N
/ j
10°
90° 105° 120°
-
135° 150° 165°E 180° 165°W 150° 135° 120° 105° 90° 75° 60°
035
450
_o
30°
-
15°W 0°
070
15°E
IIi.
30° 45
-'s..,
060
60° 15°
9J0
10°
:

149
10090° 105° 1200
135° 150° 195°F 180° 155°W 150° 135° 120° 105° 90° 15° 60°
450
300 15°W
0° 15°E
300
450
611°
750
60e
60°
450
30°
15°N
1
3469
\\
\
3469
)
3470
34 69 to 34 70
70
...,
34 70
3471
1
I
3490
_&'
34.8___._488
347
3486
I
*
3472
3488 r
15°S
3471
30°
3471
45°
34 71
>34.12
< 34 72
>34 70
3470
3470
'....3447
3466
3467 3466
3473
3474 to
3470
3469
3471
3469
34.69
60°
100
90° 105°
3468 to 3469
-
120° 135° 150° 165°F
-
180° 165°W 150° 135°
34 70 to 34 71
120° 105° 90° 15°
34 66 to 34.67
80° 45° 30° 15°W 0° 15°F 30° 45°
600
15°
900
790
30°
15°N
0°
15S
30°
60°
PLATE V.

5° 150° 135° 120° 105° 90°
750
60°
450
30° 15°W 0° 15°t 30° 45° 60°
150
150
10090° 1J5° 120° 135° 150° 165°[
600
60°
27 81
S
450
2781 to2782
30° 2782
15°N
27 80
00
27
15°S
27 85
300
2786
2785
*
2786
45
0
27
27851 tO 6 ç
2784
2785
27 82 to 27 83
; 1
>2785k
<2785
¶
60°
2789
700
90°
1050
1
1200 1350
.
1500
165°F
27 88to 27 89
180° 165°W 150°
1350
120° 105° 90° 15°
27 93
'-2792
2791 to
92
27.91
I
600
2790
2790
27.87
27 88
2790
27 87 to 27 88
27.87
27.
450
300 15°W
00
,.
4
2788
27 88
2788to 27.89
150F
30°
2786
27.87
2786
1
27 83
30°
45°
27.85
60°
150
45°
300
15°N
00
900
10°
PLATE VI. Sigma-O [i000 x (potential

70090° 105° 120° 135° 150° 165°E 180° 165°W 150° 135° 120° 105° .00° 75°
600
450
30° 15°W 0° 15°E.
30° 45° 60°
750
1
60° 60°
I
0 j
450
L.
45°
30°
36
5 2
5.3
j.
5
15°N o 4.3
J
1I
15°S
44
300
4.6
45°.+4
I
I
I
4.8
I
100
90° 105° 120°
I
135°
J
150° 165°E
4
1
46
I
L
180°.
i
.165°W
1
150° 135°
11
I
I
47
120° 105°
900
75
-
I
600
5.0
I
I
5.1
L 53
53
4.8
49I
41
--15°S
I
45° 30° 15°W 0° 15°E 30° 45° 600
750
*QJfljjflg DISCOVERY II data (otherwise 11.7)
900
100
300
PLATE VII.
Dissolved oxygen content (mi/i) near the bottom in the major deep ocean basins0
151