Jökull - 01.10.1998, Page 48

Table 6. Mass balance of drainage basins in Vatnajökull, 1993-1994. 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, 1993-1994. Bw og bw er vetrarafkoma, Bs and bs er sumarafkoma, Bn og bn ársafkoma, ELA
er hœð jafnvœgislínu, AAR er hlutfall ákomusvœðis af heildarflatarmáli jökuls. Nákvœmni 15%.
Area Bw Bs B„ bw bs b„ ELA AAR
kmJ 106m3 10‘m3 106m3 m a'1 m a'1 ma'1 m
Tungnaárjökull 308 525 -565 -40 1.70 -1.84 -0.14 1160 0.60
Köldukvíslarjökull 313 c. 450 c. -460 c. -10 c. 1.43 c. -1.47 c. -0.03 1300 0.55
Dyngjujökull 1040 1495 -1305 190 1.44 -1.25 0.19 1250 0.71
Brúarjökull 1695 2965 -2490 475 1.75 -1.47 0.28 1140 0.67
Grímsvötn 160 350 -85 265 2.19 -0.59 1.60 1.0
Fig. 9. Mass balance measurements, 1993-1994; Specific
mass balance in m water equivalent, bw: winter balance, bs:
summer balance, bn: annual net balance.
-Afkoma 1993-1994 sem metrar vatns. bw: vetrarafkoma, bs:
sumarafkoma, b„: ársafkoma. Mœlistaðir eru merktir með
krossi.
northem than the westem outlets and, for the glacier
outlets as a whole, the summer balance was more
negative on the westem than on the northem outlets.
The snowfall increased the albedo and caused an ex-
ceptionally sharp difference in the summer balance
gradient between the accumulation areas and abla-
tion areas similar to the summer of 1992. Moreover,
the ice surface emerged earlier in the summer in the
western part of the ablation area of Brúarjökull than
in the eastern part. The maximum values of the sum-
mer balance were estimated -5600 mm at 700 m on
Tungnaárjökull, -5300 mm at 600 m on Brúarjökull
and -4500 mm at 750 m on Dyngjujökull.
The specific net balance in the central area of the
ice cap was about 3000 mm. Integrated over the area
of the glaciers, the net balance of all the glaciers was
positive (Figs. 6 and 7), especially on the northern
outlets where the specific mass balance was more
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JÖKULL, No. 45, 1998