Jökull - 01.10.1998, Page 51

Table 8. Mass balance of drainage basins in Vatnajökull, 1994-1995. Bw and bw = winter balance, Bs and bs = summer balance,
Bn and bn = net balance, ELA = the equilibrium line altitude, AAR = accumulation area ratio. Accuracy 15%.
- Afkoma skriðjökla Vatnajökuls, 1994-1995. Bw og bw er vetrarafkoma, Bs and bs er sumarafkoma, Bn og b„ ársafkoma, ELA
er hœð jafnvœgislínu, AAR er hlutfall ákomusvœðis af heildarflatarmáli jökuls. Nákvœmni 15%.
Area km2 106 m’ Bs 106m3 B„ 106m3 b„ ma'1 bs m a1 b„ ma'1 ELA m AAR
Köldukvíslarjökull 313 407 -593 -183 1.30 -1.89 -0.59 1410 0.45
Dyngjujökull 1040 1533 -1513 20 1.47 -1.45 0.02 1310 0.65
Brúarjökull 1695 2770 -3112 -342 1.64 -1.84 -0.20 1260 0.50
Fig. 11. Mass balance measurements, 1994-1995; Specific
mass balance in m water equivalent, bw: winter balance, bs:
summer balance, bn: annual net balance.
- Afkoma 1994-1995 sem metrar vatns. bw: vetrarafkoma,
bs: sumarafkoma, bn : ársafkoma. Mœlistaðir eru merktir
með krossi.
dukvíslarjökull (Bárðarbunga). The summer tempera-
ture was 0.3 °C below the average of 1931-60 (Veðr-
áttan, 1994); cold in June but July was relatively
warm. The specific summer balance at 1100-1200 m
elevation (i.e. close to the equilibrium line) was simi-
lar on Tungnaárjökull and Brúarjökull but lower on
Dyngjujökull. This difference between the summer
balance on Dyngjujökull and on Brúarjökull in-
creased at lower elevations in the ablation areas, re-
flecting lower albedo on Dyngjujökull than on Brúar-
jökull. The maximum values of the summer balance
were estimated -6500 mm at 750 m on Dyngjujökull,
-5700 mm at 700 m on Tungnaárjökull and -4500 mm
at 600 m on Brúarjökull.
The specific net balance in the central areas of
Vatnajökull was close to 2 m, the lowest value
mesured since the project started in 1991/1992. The
total net mass balance of the northern outlets was
slightly positive but negative on the western outlets
(Table 6). The equilibrium line on Brúarjökull was at
1100 m on the eastern part and 1170 m on the western
part. The net balance on Tungnaárjökul was negative
and the equilibrium line was at 1160 m. On Örœfa-
jökull (1800 m a. s. 1.) the annual net balance was 7.8
m water equivalent which definitely is a record for
precipitation in Iceland.
JOKULL, No. 45, 1998
49