Jökull - 01.06.2000, Blaðsíða 17

Ice-thickness measurements on Sólheimajökull
CONCLUSIONS
1. Sólheimajökull was found to occupy an over-
deepened parabolic trough, ranging from one to two
kilometres in width and reaching a maximum depth
of 430 m. The glacier was thicker and had a grea-
ter extent in 1996 than as shown on the DMA map.
This reflects the glacial advance of 482 m that occur-
red between 1970 and 1995.
2. Sólheimajökull has the characteristics of an acti-
ve glacier that flows regularly, is very sensitive to
climatic change, and responds quickly. The current
advance is likely to reflect recent changes in mass bal-
ance. No evidence of surge-type behaviour could be
found.
ACKNOWLEDGEMENTS
We thank the National Geographic Society, the Car-
negie Trust for Universities of Scotland and the
NABO programme (National Science Foundation
of America) who supported various aspects of this
project. Dan Millington and Ágúst Bjartmarsson
of Björgunarsveitin Víkverji provided field assist-
ance. Andrew Mackintosh is grateful for the supp-
ort of an ORS Award and a University of Edinburgh
Geography Department Studentship. We also thank
the two anonymous referees whose valuable comm-
ents improved the manuscript.
ÁGRIP
ÍSSJÁRMÆLINGAR Á SÓLHEIMAJÖKLI
Issjármælingar með punktíssjá sýna að Sólheimajök-
ull er allt að 433 m þykkur og liggur í 10 km löngum,
U-laga dal sem nær niður undir sjávarmál á u.þ.b. 3,5
km kafla innan við núverandi jökulsporð. Þarna hef-
ur því sennilegast verið fjörður við hærri sjávarstöðu
snemma á nútíma (Holocene). Jökullinn er um 200 m
þykkur við jaðar Kötluöskjunnar en að meðaltali um
tvöfalt þykkari neðan hennar. Lögun jökulsins gefur
til kynna að hann sé næmur fyrir veðurfarsbreyting-
um. Framskriðið á árunum 1970-1995 stafar líkleg-
ast frá aukinni ákomu ofarlega á jöklinum undanfarna
áratugi.
REFERENCES
Bjömsson, H. 1979. Glaciers in Iceland. Jökull 29, 74-80.
Bogorodskii, V.V., Bentley, C.R. and Gudmundsson, RE.
1985. Radioglaciology. Reidel, 254 pp.
Dowdeswell, J.A., J. O. Hagen, H. Björnsson, A. F.
Glazovsky, W. D. Harrison, P. Holmlund, P. Jania, J.,
R. M. Koerner, B. Lefauconnier, C. S. L. Ommanney
and R. H. Thomas 1997. The mass balance of circum-
arctic glaciers and recent climatic changes. Quatern-
ary Research 48, 1-14.
Dugmore, A. J. 1989. Tephrochronological studies of
Holocene glacier fluctuations in south Iceland. In J.
Oerlemans (Ed.) Glacier Fluctuations and Climatic
Change. Kluwer Academic Publishers. pp 37-56.
Dugmore, A. J. and D. E. Sugden 1991. Do the anom-
alous fluctuations of Sólheimajökull reflect ice-divide
migration? Boreas 20, 105-113.
Firbish, D. J. and J. T. Andrews 1984. The use of hyp-
sometry to indicate long term stability and response of
valley glaciers to changes in mass-transfer. Journal of
Glaciology 30, 199-211.
Jóhannesson, T., C. Raymond and E. Waddington 1989.
Time scale for adjustment of glaciers to changes in
mass balance. Journal of Glaciology 35, 355-369.
Lawler, D. M., H. Bjömsson and M. Dolan 1996. Impact of
sub-glacial geothermal activity on meltwater quality in
the Jökulsa á Sólheimasandi system, Southem Iceland.
Hydrological Processes 10, 557-578.
Magellan, 1991. Post Processing Software Version 4. Mag-
ellan Systems, San Dimas, Califomia 91773.
Oerlemans, J. 1989. On the response of valley glaciers
to climatic change. In J. Oerlemans (Ed.) Glacier
Fluctuations and Climatic Change. Kluwer Academic
Publishers. pp 353-372.
Paterson, W. S. B. 1994. The Physics of Glaciers (Third
Edition). Pergamon. 480 pp.
Sigurðsson, O. 1998. Glacier variations in Iceland 1930-
1995. Jökull 45, 3-25.
Stötter, J. 1994. Changing the Holocene Record- A call
for international, interdisciplinary co- operation. In J.
Stötter and F. Wilhelm (eds.) Environmental Change
in Iceland. Munchener Geographische Abhandlungen
Reihe B, 257-274.
Watts, R. D. and A. W. England 1975. Radio-echo sound-
ing on South Cascade Glacier Washington, using a
long wavelength mono-pulse source. Journal of Gla-
ciology 15, 459-461.
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