Jökull - 31.12.2001, Side 80

Helgi Björnson et al.
accumulation there is fairly sensitive to the winter
temperature and position of the paths of the North
Atlantic lows pressure weather fronts passing Iceland.
No simple relationship can be seen between the win-
ter balance on Langjökull and the winter precipitation
at a nearby meteorological station (Hveravellir). The
minimum winter balance in 2001. however, coincided
with a minimum winter precipitation at the station.
The net balance has been negative over the entire sur-
vey period from 1996 to 2001 and the accumulation
area has varied from 10% to 40% of the glacier area.
The total mass loss over the period 1996-2001 was
5.73 m (5.36 km3 water equivalent), or 3% of the total
ice mass of Langjökull.
Acknowledgments
The work was carried out in collaboration between the
National Power Company and the Science Institute,
University of Iceland. Since 1996 the work has been
supported by EU-funds (TEMBA 1996-1997, ENV4-
CT95-0105, and ICEMASS 1998-2001, ENV4-
CT97-0490). Support from the Research Fund of the
University of Iceland is acknowledged. Some of the
data were collected during expeditions of the Iceland
Glaciological Society.
ÁGRIP
Afkoma Vatnajökuls (1991-2001) og Langjökuls
(1996-2001)
Raunvísindastofnun Háskólans hefur á hverju ári
1991 til 2001 mælt afkomu Vatnajökuls í samstarfi við
Landsvirkjun, og frá 1996 með styrkjum frá Evrópu-
sambandinu. Á sama hátt hefur afkoma Langjökuls
verið mæld frá 1996 til 2001. Afkoman var mæld vor
og haust í punktum, sem voru dreifðir með hæð frá
sporðum til hæstu svæða, 40-50 á Vatnajökli og 22
á Langjökli. Fyrstu þrjú árin var afkoma Vatnajök-
uls jákvæð, nálægt jafnvægi fjórða árið en hefur síðan
verið neikvæð. Alls rýrnaði Vatnajökull um 19,4km3
frá 1991 (2,37 m af vatni jafndreift yfir jökulinn) og
missti um 0,6% af ísmassa sínum. Afkomutölur ein-
staka skriðjökla eru í töflu I. Afkoma Langjökuls hef-
ur verið neikvæð öll þau fimm ár sem hún hefur verið
mæld, 1996-2001, samtals um 5,36 km3 (5,73 m), og
ísforði hans rýrnaði um 3%.
REFERENCES
Björnsson, H., F. Pálsson, M. T. Guðmundsson and
H. H. Haraldsson, 1999. Mass balance of western and
northern Vatnajökull, Iceland, 1991-1995. Jökull 45,
35-58.
78 JÖKULLNo. 51