Chapter 3
Precipitation
1.
With the precipitation data used by Dansgaard (1964) to produce his global T–18O relationship (Fig. 3-1),
produce regression lines for the regional subsets from low to high latitude (Island stations, North Atlantic,
Greenland and Antarctica). These data can be taken from this table or the regression lines plotted directly on a
copy of this figure. Discuss their change in slope with increasing latitude in the context of rain-out and
Rayleigh distillation.
T
Isl.
18O
-4
5
5
12
24
-9.0
-8.0
-5.0
-2.5
-1.0
T
N.Atl.
8
-16
-7
-3
-8
18O
-6.5
-24.0
-17.5
-17.0
-14.0
18O
T
0
-1
0
1
0
6
-15.5
-13.5
-13.0
-13.2
-12.5
-12.0
T
18O
5 -10.5 Grnld
8 -9.5 , -30
7 -8.0
-28
10 -8.0
-24
10 -7.5
-24
12 -6.0
-20
T
18O
-35.0
-34.0
-31.0
-29.5
-29.0
T
-20
-16
-14
Ant.
-50
-41
18O
-28.5
-24.5
-23.5
T
-27
-23
-19
-22
18O
-32.0
-20.0
-19.0
-27.1
-49.0
-42.0
2.
Use the results of your regression equation for Greenland and for Antarctic data from Dansgaard (1964) to
calculate a mean temperature for the last glacial maximum (LGM) at the end of the Pleistocene, and the early
Holocene at the Camp Century site and at Vostok Station. What was the change in mean annual temperature for
each site during this period of climate warming?
3.
Copy and paste the mean monthly precipitation data provided here onto a spreadsheet and plot to calculate the
parameters of meteoric waters together with the following interpretations.
BERMUDA
32.37N/64.68W, 6 m a.s..l
month
18O
2H
Jan-63
Feb-63
Mar-63
Apr-63
May-63
Jun-63
Jul-63
Aug-63
Sep-63
Oct-63
Nov-63
Dec-63
-3.1
-2.7
0.9
-4.8
-2.6
-2.7
-3.5
-1.3
-5.4
-5.5
-5.5
-3.7
-9
-16
-3
-26
-12
-12
-18
-3
-35
-34
-37
-16
EUREKA, N.W.T., CANADA
80.00N/85.56W, 10 m a.s.l.
month
18O
2H
Jan-89
Feb-89
Mar-89
Apr-89
May-89
Jun-89
Jul-89
Aug-89
Sep-89
-32.7
-34.9
-34.4
-31.7
-37.6
-22.1
-16.4
-21.0
-26.7
-263
-278
-260
-233
-277
-169
-162
-163
-201
T°C
17.2
17.2
17.7
17.5
21.3
24.4
26.9
27.1
26.1
23.3
20.6
17.2
T°C
-42.5
-36.6
-38.7
-26.3
-13.7
2.2
6.7
5.1
-5.4
OTTAWA, ONTARIO, CANADA
45.32N/75.67W, 114 m a.s.l.
precip month
T°C
18O
2H
(mm)
40 Jan-88
-15.4
-112
-9
20 Feb-88
-15.6
-114
-9.3
90 Mar-88
-11.3
-78
-3.3
50 Apr-88
-11.6
-82
6
30 May-88
-5.7
-44
14.9
70 Jun-88
-7.3
-50
17.6
20
Jul-88
-9.0
-63
22.7
70 Aug-88
-7.8
-54
20.3
5 Sep-88
-8.2
-61
14.1
94 Oct-88
-13.4
-99
5.9
60 Nov-88
-12.5
-90
2.7
15 Dec-88
-14.2
-95
-8.3
precip
(mm)
37
80
27
92
32
94
78
21
68
13
83
45
WACO, TEXAS, 1975
31.62N/97.22 W, 156 m a.s.l.
precip month
18O
2H
(mm)
2 Jan-75
-8.7
-57.1
14 Feb-75
-7.12
-47.1
2 Mar-75
-3.98
-15.9
2 Apr-75
-3.11
-7.5
2 May-75
-4.44
-23.9
13 Jun-75
-3.84
-20.8
40
Jul-75
-2.66
-8.6
17 Aug-75
0.32
10.8
11 Sep-75
-5.61
-27.3
precip
(mm)
36
75
28
16
48
72
70
18
58
T°C
9.2
8.3
12.4
17.8
22.2
26.5
27.8
29.2
25.1
Oct-89
Nov-89
Dec-89
-33.6
-34.9
-39.4
-256
-267
-305
VICTORIA, CANADA
48.65N/123.43W, 20 m a.s.l.
month
18O
2H
Jan-76
Feb-76
Mar-76
Apr-76
May-76
Jun-76
Jul-76
Aug-76
Sep-76
Oct-76
Nov-76
Dec-76
-11.3
-11.9
-9.2
-10.9
-8.2
-6.3
-7.9
-9.4
-6.7
-9.3
-5.8
-7.6
-87
-87
-70
-91
-63
-49
-71
-67
-52
-67
-40
-54
-19.9
-28.3
-36.5
T°C
8
14
12
36
34
37
26
17
15
17
13
8
9
13
2
Oct-75
Nov-75
Dec-75
-3.25
-0.73
-7.78
-8.2
6
-46.2
WACO, TEXAS, 1976
31.62N/97.22 W, 156 m a.s.l.
precip month
18O
2H
(mm)
94
Jan-76
-4.12
-24.3
47 Feb-76
0.79
13
57 Mar-76
-0.73
-2
42 Apr-76
-3.45
-22.9
43 May-76
-0.17
-5
24
Jun-76
-3.21
-23.4
18
Jul-76
-0.76
-11.9
46 Aug-76
-3.08
-17.8
16 Sep-76
-5.51
-27
46 Oct-76
-7.05
-43.9
34 Nov-76
-6.53
-38.5
67 Dec-76
-7.28
-45.2
21.4
15.4
10.4
61
10
47
T°C
precip
(mm)
44
8
39
66
27
82
88
6
44
32
17
64
8.2
15
15.8
19
21.5
26.9
27.9
29.8
25.5
15.8
10.1
7.5
Determine the equation defining the meteoric water line for each station, and the annual average value for
deuterium excess d. From these parameters, determine the average humidity in the source region for the
precipitation at each station, and any observation of secondary evaporation (post-condensation evaporation).
Station
LMWL
Bermuda
Ottawa 1988
Ottawa 1989
Eureka
Waco 1975
Waco 1976
Victoria


d
h
secondary
evaporation


Repeat this calculation for Eureka, dividing the data into two sets: Jun–Oct and Nov—Apr. Comment on the
seasonal differences in the source of water vapour at this station.
Are the Waco 1976 data biased by an amount effect, and if so, how does it affect the LMWL? What about the
precipitation data for Ottawa?
Calculate the annual 18O value and monthly T–18O correlation for each station. Which stations have the
strongest correlations (based on r2 value).