Jökull - 01.10.1998, Page 43

2000
Síöujökull 1991-92
CD
800
-6000 -2000 2000 6000
specific balance (mm)
- Tun gnaárjc kull 19 >1-92
■ S" bs 4
l
- / I
/7 ■

Æf d

-8000 -4000 O 4000
specific balance (mm)
Kölc iukvísls rjökull 991 -92 7
■ L I 1
1 S
7

-8000 -4000 O 4000
specific balance (mm)
Tungna dratnag k water 5 basín
2-

7
//
i i

-4000 O
specific balance (mm)
100 O 10
cumulative balance (106m3)
500-1000 O 1000
cumulative baiance (106m3)
Fig. 5. Mass balance as a function of ele-
vation 1991-1992 for various drainage
basins; bw and Bw: winter balance, bs and
Bs: summer balance, bn and Bn: annual
net balance.
- Afkoma sem fall af hœð á nokkrum
skriðjðklum, 1991-1992; b„ og Bw:
vetrarafkoma, bs og Bs: sumarafkoma, bn
og Bn: ársafkoma; (b sem metrar og B
rúmmetrar vatns).
basins (Table 2), the winter balance at 27 points (Fig.
4) from April 27 to May 1, and the summer balance at
20 points in the period September 29 to October 6. On
Síðujökull, Köldukvíslarjökull and Dyngjujökull, the
mass balance was only measured in the accumulation
area. On Dyngjujökull, measurements of the summer
balance are lacking in the lowest part of the ablation
area but the summer balance is estimated by extrapo-
lation of the measurements from Tungnaárjökull and
Köldukvíslarjökull, based on correlations obtained
from data collected after 1992. The main results are
given in Figs. 4 and 5 and Table 2.
The highest values for the winter balance (2.8 to
3.3 m) were observed on Síðujökull and towards
Grímsvötn. For a given elevation, the accumulation
was about 500 mm higher on Síðujökull than on the
other outlets (Figs. 4 and 5). The increase in winter
accumulation with elevation was, however, similar on
all the outlets, about 200 mm/100 m. Snow drift obvi-
ously caused fluctuations of mass balance as a func-
tion of elevation e.g. on Tungnaárjökull. The average
winter balance on Dyngjujökull was exceptionally
high (2 m). Cyclonic activity was high and southwest-
erly winds were frequent. Anticyclonic circulation
JÖKULL, No. 45, 1998
41