Intercalibration at Sea of Hydrographic and Chemical Observations
Aboard the USSR Ship PROFESSOR VIESE and the US Research Vessel
1PSON during FDRAKE 76
G C 8 5 6
1
0735
AnISOS Technical Report
a..
no.77-7
cop.2
'Mar 1 ne
Louis I. Gordon
George
School of Oceanography
Oregon State University.
Corvallis,
OR
97331
C.
Anderson
Scripps Institution of
Oceanography
La Jolla, CA
92037
Worth
D.
Nowlin, Jr.
Department of Oceanography
Texas A&M University
College Station, TX 77843
Sponsored by the
Office for the International Decade of Ocean Exploration
of the National SCience Foundation
August 1977
OSU Reference No. 77-7
Results of an Intercalibration at Sea of Hydrographic and
Chemical Observations and Standards Aboard the USSR Ship PROFESSOR VIESE
and the US Research Vessel THOMAS G. THOMPSON during FDRAKE 76
An ISOS Technical Report
Louis I. Gordon
School of Oceanography
Oregon State University
Corvallis, OR 97331
George C. Anderson
Scripps Institution of Oceanography
La Jolla, CA 92037
Worth D. Nowlin
Department of Oceanography
Texas A&M University
College Station, TX
77843
Sponsored by the
Office for
August 1977
the International Decade of Ocean Exploration
of the National Science Foundation
OSU Reference No. 77-7
ABSTRACT
On 15 February 1976 the USSR Research Ship PROFESSOR VIESE and the
US R/V T.G. THOMPSON rendezvoused in the southern Drake Passage.
The
ships simultaneously occupied hydrographic stations as close together as
feasible.
Calibration standards for
salinity,
dissolved oxygen, and
dissolved reactive phosphate and silicate were then exchanged by the two
scientific
parties.
The calibration standards were found to be in very
good agreement, the differences being insignificant with respect to
measurement precision.
The results of the hydrographic station intercomparison showed aver-
age differences with regard to sign between the two ships' results for
temperature, salinity, dissolved oxygen, reactive phosphate, and reactive
silicate to be realtively small but the root-mean-square differences to
be quite large.
This indicates that general comparisons of the two data
sets are possible, whereas detailed considerations are not reasonable
because of serious measurement errors aboard VIESE.
INTRODUCTION
During February of 1976 the R/V T.G. THOMPSON, operated by the University of Washington, and the R/V PROFESSOR VIESE were both working in the
Drake Passage.
The THOMPSON was being used in the field operation FDRAKE 76
as part of International Southern Ocean Studies (ISOS), while the VIESE,
operated by the Arctic and Antarctic Research Institute of the USSR, was
participating in the POLEX-South program.
Prior agreement had been made for
these two vessels to rendezvous in the Drake Passage in order to exchange
standard materials, and to simultaneously occupy hydrographic stations at
positions as close together as safety permitted.
On 15 February the vessels
rendezvoused at 60024'S, 61°19'W.
COMPARISON OF THE STANDARD MATERIALS
During the reciprocal visits by Soviet and American scientists to the
two research vessels, standard materials were exchanged for subsequent
laboratory comparisons on both ships.
Standards exchanged were for
salinity, dissolved oxygen, phosphate, and silicate.
In addition, the
Soviets supplied pH standards and the Americans supplied nitrate standards.
We now present the results of the comparisons of the salinity, oxygen,
phosphate, and silicate standards done aboard THOMPSON.
a.
Salinity
One case (25 vials) of Soviet standard seawater was received from the
PROFESSOR VIESE.
This water was labeled as batch C81
a nominal chlorinity of 19.379%;.
dated 6/V 1974 with
The salinity of six Soviet samples was
determined using a University of Washington (1960) conductive salinometer
2
Table 1.
Comparison of USSR and SIO dissolved oxygen standards.*
Nominal USSR
Concentration
Observed USSR
Concentration
(N)
(N)
N-2/SIO-1
0.010154
0.010152
0.02
N-2/SIO-2
0.010154
0.010164
-0.10
N-14/SIO-3
0.010073
0.010044
0.29
Standard
Pair
Mean Diff. + 1 SD
Difference
(%)
+ 0.07 + 0.20
* The standard solutions made up from the USSR starting materials were measured as unknown samples using the SIO materials as standards. Three or
Nominal
more replicate titrations were made of all standards and blanks.
concentrations given here are based upon label weights. The USSR vial
labels indicated that the contents were for preparation of a .01000 N
solution, but the listed weight of KIO on the two vials were 1.54 and
0.73% greater than that recommended fo11 an .01000 N solution (Carpenter,
1965).
3
Oceanography.
(no. 14), owned and maintained by the Scripps Institution of
samples were
The salinometer was standardized before and after the Soviet
batch P67, dated 10/8
processed using Copenhagen standard seawater:
Based on this standardization,
1974, and nominal chlorinity of 19.3735°/°°.
lower than the inthe values obtained for five of the Soviet standards were
Soviet sample
dicated salinity by approximately .002°/°°, while the sixth
was lower than the indicated salinity by .003°/ °.
The accuracy of this
method of salinity determination is about this same value.
The precision of
the salinometer is between .0005 and .001°/°°.
b.
Dissolved oxygen
(KI03)
Two sealed glass ampoules of dried preweighed potassium iodate
powder were received from the PROFESSOR VIESE.
These were compared with
Institution
three preweighed standards, also KIO35 prepared at the Scripps
of Oceanography (SIO).
Standard solutions (nominally O.O1000N) were pre-
outlined
pared from both sets of dry materials according to the procedure
by Anderson (1971).
The same volumetric glassware and distilled water were
used for preparing all standard solutions.
Blanks determined using either
the same
set of standards according to the method in Anderson (1971) were
within experimental error.
Ten cc. aliquots of both standards were titrated
in replicates of three to eight titrations and the averages compared.
The results are shown in Table 1.
We made the comparison on the basis
the
of the exact weights of KIO3 given on the VIESE ampoule labels, using
THOMPSON solutions as working standards.
We consider the agreement of 0.1%
to be very good, and probably not significantly different from zero.
If
with
real, the difference could have arisen from (1) our lack of experience
possithe sealed glass ampoules used for the VIESE standards and resulting
4
Comparison of USSR and OSU nutrient standards.*
Table 2.
Experiment
19 Feb. 1976
7 Mar. 1976
Mean:
*
Silicate
Phosphate
Date of
Nominal
Concn.
Observed
Concn.
Diff.
( mol/1)
( mol/1)
(%)
2.409
2.42
"
2.39
2.409
2.405
Observed
Concn.
Diff.
( mol/1)
( mol/1)
(%)
85.4
83.2
Nominal
Concn.
86.2
0.15
85.4
84.7
0.8
The standard solutions made up from the USSR starting materials were measured
as unknowns using the OSU materials as standards. Five or more replicate
comparisons of the solutions were made on the AutoAnalyzer on each date. Blanks
made up in the same matrix as the standards were subtracted from both sets of
absorbances before calculations.
5
ble loss of some material during transfer to the volumetric flask; (2) a
suggestion from previous data on standard SIO-1 that it might have been
slightly high in concentration.
c.
Nutrients
Standard materials for phosphate and silicate brought aboard THOMPSON
from the PROFESSOR VIESE were preweighed dry potassium dihydrogen phosphate
(KH2PO4) powder in two glass vials and solutions labelled "500 mg Si as
The Oregon State University
SiO2 3per liter", in two plastic bottles.
(OSU) nutrient standards in use on FDRAKE 76 were preweighed powdered
materials stored in screw capped glass vials.
The phosphate standard was
also KH2PO4 that had previously been compared with US National Bureau of
Standards NH4H2PO4, Standard Reference Material No. 149.
The silicate
standard was sodium fluosilicate, Na2SiF6 that had been compared with S102
of stated 99.89% purity obtained from a vendor who supplies high purity
material to the semiconductor industry.
Both comparisons had been carried
out in natural seawater matrices.
In the present work two comparisons were made, in identical
natural
seawater matrices, each starting with a different sample of both US and
USSR standard on two different dates about two weeks apart.
Standard
solutions were prepared as described by Nowlin et al. (1977). Five or more
replicate comparisons were made on the ISOS precision AutoAnalyzer system
on each date.
The results are given in Table 2 with the OSU materials
arbitrarily used as standards and the measured USSR concentrations compared
with their nominal values.
The two sets of standards are indistinguishable
for phosphate and probably so for silicate.
6
THE HYDROGRAPHIC STATIONS
Two hydrographic casts with STD attached to the wire were.made from the
THOMPSON (TGT).
The STD used was a Plessey model 9040 with both analog and
The recorded sonic depth, corrected using Matthews
digital data recording.
(1939) tables and the depth of the ship's transducer, was 3733 m, and the
second from 1 m to 590 m.
two casts..
A total of 33 Nansen bottles were used on the
Depths were determined from paired protected
reversing thermometers on all bottles below 75 in.
and unprotected
For each bottle in situ
temperature, salinity, dissolved oxygen, and reactive inorganic phosphate,
silicate, nitrate and nitrite were determined.
With the exceptions of
nitrate and nitrite measurements, the bottle data from both casts are listed
in Table A of the Appendix and plotted in Figure 1.
The quality of these
data is representative of that obtained on THOMPSON during FDRAKE 76 and
that obtained on the R/V MELVILLE during FDRAKE 75.
The profiles are quite
smooth.
PROFESSOR VIESE (PV) made two hydrographic casts, the first from 661
to 3575 m, and the second from the surface to 636 in.
were used on the two casts.
A total of 30 bottles
Temperature, chlorinity, dissolved oxygen, in
situ pH, reactive inorganic phosphate, and reactive silicate were measured.
The measured data, excepting pH, are listed in Table B of the Appendix and
plotted in Figure 2.
The nutrient and oxygen profiles are quite irregular
and contain many one-point maxima and minima indicating that large measurement errors are present.
Table 3 summarizes the average differences for the vaiables measured
by both vessels, the rms deviations between the data sets, and the numbers
of differences employed in making the computations.
The differences were
TEMP (DEG C)
0
1
1
2
1000
2000
0
W
0
3000
40001
1
FIG
'
1
--
:
TGT STN. H21
SALINITY (PPT)
34.0
35.0
34..5
i
4000
FIG 1-B: TGT Sm.
H21
OXYGEN (ML/L)
8.0
7.0
6.0
5.0
r-.
2000
F-
W
0
3000
4000
1
1
--,
-L
FIG 1-C: TGT Sl'N.
H21
0.0
2 000
PHOSPHATE (UM/L)
1.0 2.0 3.0 4.0 5.0
i
-
3000
4000
FIG 1-D: TGT STN.
H21
SILICATE (UM/L)
50
100
1000
2800
3ee0 L
FIG 1-E: TGT STN. H21
150
TEMP (DEC C)
0
1
2
FI C 2-A: 8U 8T N. 28 ? 7
SALINITY (PPT)
33.5
0
34.0
34.5
35.0
0
3000L
FTC 2-B: PU STN. 2817
OXYGEN CMLiL)
5.0
6.0
7.0
1000
2000
F---
0_
LU
0
3000 !-
4000
FIG 2-C: PU STN. 2817
8.0
r--
0.0
0
PHOSPHATE (UMiL )
1.0
2.0
3.0
4.0
1000
2000
n
LU
Cl
3000
4000
FIG 2-D: FU SIR 2817
5.0
16
SILICATE CUM/L)
50
100
3000
4000
F I ( 2-E: PU STN. 2817
150
17
Table 3.
x
rms dev.
n
Statistical comparison of the THOMPSON and VIESE
intercalibration station results.
AT
oS
(°C)
(°/°°)
-0.003
0.12
30
0.0000
0.04
31
002
(ml/1)
AP04
nSi
(umol/1)
(umol/1)
-0.02
-0.15
-0.94
0.19
0.47
7.6
30
31
31
x denotes
the averages,with regard to sign, of oT's, AS's, etc. (TGT-PV). n denotes
the numbers of differences used in the computations for each variable.
Individual differences were computed as explained in the text.
18
computed as the difference (TGT-PV) between the TGT observations and the PV
observations linearly interpolated at the depths of the TGT observations.
In general, the rms deviations are one or more orders of magnitude greater
than either the signed average differences or the calibration discrepancies
discussed earlier in this report.
Although the numbers of paired observations
are not large and the conclusion, therefore, not definite, histograms of the
differences indicate that they are not randomly distributed in the cases of
most of the measurements.
SUMIARY AND CONCLUSIONS
The compatability of two data sets depends upon the agreement of analytical standards, the measurement techniques, and procedures employed by
shipboard analysts.
From this work it appears that the USSR and USA stand-
ard materials used to calibrate the measurements in the respective national
Antarctic programs are in very good agreement.
The salinity standards
agree to within 0.002°/°° and are indistinguishable as sets.
The dissolved
oxygen standards agreed to within 0.1% while the nutrient standards agreed
to within 0.2% for phosphate and .08% for silicate.
discrepancies are within experimental error.
The oxygen and nutrient
Thus it appears that the
the
fundamental bases for accuracy and intercomparability of data sets,
analytical standards employed, are in good agreement.
Since the signed average differences between TGT and PV measurements
(Table 3) are small, it is clear that the basic measurement techniques and
analytical procedures are comparable.
The rms deviations between individual
pairs of observations are large, however.
This is true for each of the
is not
variables commonly measured except salinity, where the disagreement
exceptionally large in view of the fact that the PV measurements were reported as chlorinity to .01°/°0 only.
As can be seen clearly from comparing
19
the property versus depth plots of Figures 1 and 2, the large deviations result from scatter of the PV data about the TGT data values, especially in
the cases of phosphate and silicate.
Since the signed average differences
between TGT and PV data are much smaller than the rms deviations (In fact,
they are of the same order of magnitude as the difference between standard
materials.), it seems likely that the differences between the two data sets
are due to measurement error.
Further, because the TGT vertical profiles
are smooth while the PV profiles are quite irregular with many one-point
maxima and minima we conclude that the errors are present in the PV data
set.
20
REFERENCES
Anderson, G.C. 1971. "Marine Technicians Handbook. Oxygen Analysis."
Scripps Institution of Oceanography. Reference No. 71-8. Sea Grant
Publication No. 9. La Jolla, California. 29 p.
The Chesapeake Bay Institute technique for the
1965.
Carpenter, J.H.
141-143.
Winkler dissolved oxygen method. Limnol. and Oceanog., 10:
pure water and
Matthews, D.J. 1939. Tables of the velocity of sound in
Second Edition.
sound-ranging.
sea water for use in echo-sounding and
52
p.
282:
Hydrographic Department, Admiralty, H.D.
1975
Nowlin, W.D. Jr., T. Whitworth III, L.I. Gordon, and G.C. Anderson.
Aboard
R/V
MELVILLE
during
'.'Oceanographic Station Data Collected
Oceanography, Texas A&M
FDRAKE 75." Reference 77-2-D, Department of
University.
Department of Oceanography Technical
University of Washington. 1960.
Report No. 66, U.W. Ref. 60-18.
21
APPENDIX
Table A.
Corrected, observed hydrographic and chemical data, Station 21,
FDRAKE 76, R/V THOMPSON.
Table B.
Corrected, observed hydrographic and chemical data, Station 2817,
Expedition 24-I, PROFESSOR VIESE.
22
Corrected, observed hydrographic and chemical data, Station 21,
FDRAKE 76, R/V THOMPSON.
Table A.
Depth
(m)
96
106
120
144
-0.61
0.25
02
(mQ/
33.837
34.100
34.130
34.167
34.276
7.91
5.01
7.29
7.05
6.74
5.90
PO 4
Si
(PM/9-)
(uM/Q)
1.58
2.12
2.19
2.23
14.5
44.6
47.3
50.3
2.31
58.1
2.39
2.42
2.43
2.42
2.42
67.9
72.5
75.5
78.2
80.6
82.4
83.4
84.4
86.0
87.4
291
1.867
1.848
34.399
34.481
34.509
34.558
34.594
340
389
439
489
539
1.905
1.89
1.906
1.898
1.89
34.623
34.638
34.656
34.674
34.690
4.15
4.16
4.18
4.24
4.19
2.40
2.37
2.33
590
667 A
763 A
1.875
1.85
859 A
955 A
1.72
1.63
34.702
34.712
34.722
34.728
34.732
4.25
4.23
4.35
4.36
4.44
2.26
2.28
2.23
2.24
2.21
88.2
88.4
89.6
92.7
95.8
34.731
4.51
34.727
34.724
34.716
34.712
4.58
4.66
4.79
2.23
2.25
2.25
2.27
2.28
103.0
108.5
113.8
119.0
123.6
34.707
34.706
34.703
34.705
34.703
4.82
4.82
4.87
4.89
4.90
2.28
2.29
2.28
2.28
2.29
128.0
131.7
133.0
133.8
134.8
34.697
34.698
34.697
4.93
4.95
4.92
2.31
133.7
133.5
133.7
1.12
1.60
169
193
217
242
1.61
1.81
1191
1432
1669
1910
2153
A
A
A
A
A
1.429
2390
2630
2873
3115
3358
A
A
A
A
A
0.65
0.60
0.53
0.48
0.48
3552 A
3650 A
3699 A
B)
(°/°°)
2.03
-0.95
-0.82
1
A)
S
T
(°C)
1.251
1.082
0.85 B
----
0.436
0.439
0.435
B
4.50
4.41
4.21
4.22
4.71
2.31
2.27
2.32
2.30
Cast I.
The temperature, listed to
Both protected thermometers malfunctioned.
inferred
from the pressure
the nearest five (.05) hundredths, was
thermometer, wire depth and L-Z curve.
23
Corrected, observed hydrographic and chemical
Expedition 24-I, PROFESSOR VIESE.
Table B.
0
PO44
data, Station 2817,
Si
Depth
T
Cl
(m)
(°C)
(°/°°)
(m11)
(uM/1)
(uM/1)
26
52
79
1.99
2.00
1.85
1.59
-1.09
18.725
18.710
18.723
18.724
18.832
---7.84
7.84
7.82
7.65
2.23
2.23
2.35
2.24
2.30
14.27
13.94
13.30
14.16
105
-0.71
18.888
19.032
19.094
6.84
5.78
5.04
4.59
4.29
2.23
2.26
2.43
2.42
2.43
47.39
4.14
---4.15
4.26
2.43
---2.19
2.43
2.45
79.81
1.63
1.55
1.65
1.62
3.13
97.27
91.97
0
11
131
157
208
261
0.27
0.98
1.53
1.77
19.117
19.127
314
366
419
472
524
1.81
1.84
1.88
1.90
1.89
19.140
19.155
19.170
19.177
19.182
636
1.82
1.82
1.76
1.68
1.63
19.197
19.204
19.225
19.226
19.224
4.27
4.25
4.32
4.35
1.39
1.18
1.02
0.85
0.67
19.222
19.215
19.223
19.215
19.208
4.56
0.53
0.50
0.46
0.45
0.40
19.197
19.196
19.194
19.188
19.191
4.96
4.94
4.89
4.86
5.04
661
756
848
935
1207
1481
1755
2029
2288
2546
2804
3061
3318
3575
4.21
4.51
4.61
4.70
4.85
5.51
2.24
2.40
4.12
2.24
2.26
3.25
3.74
2.35
2.21
2.28
40.28
65.91
54.41
85.43
91.35
-----
62.36
93.53
90.10
98.21
101.9
99.77
96.96
112.5
101.6
126.5
126.5
135.9
104.1
143.7
136.8
139.3