HR: 1340h
AN: C23A-1153    [Abstracts]
TI: Long-term High Arctic Mass Balance: Comparison of Specific Balances and Volume Changes.
AU: * Kohler, J
EM: jack@npolar.no
AF: Norwegian Polar Institute, Polar Environmental Centre, Tromsø, N-9296 Norway
AU: Brandt, O
EM: ola@npolar.no
AF: Norwegian Polar Institute, Polar Environmental Centre, Tromsø, N-9296 Norway
AU: Nuth, C
EM: chris2@npolar.no
AF: Norwegian Polar Institute, Polar Environmental Centre, Tromsø, N-9296 Norway
AU: Murray, T
EM: T.Murray@swansea.ac.uk
AF: Dept. Geography, U. of Wales., Swansea, SA2 8PP United Kingdom
AU: James, T
EM: t.d.james@swansea.ac.uk
AF: Dept. Geography, U. of Wales., Swansea, SA2 8PP United Kingdom
AU: Barrand, N
EM: geo1neb@leeds.ac.uk
AF: Dept. Geography, U. of Wales., Swansea, SA2 8PP United Kingdom
AB: The mass balance record from Midtre Lovénbreen, Svalbard, is one of the longest high Arctic records (1968-present); available data includes areally-averaged winter, summer, and net balances. Balances by elevation, however, have not been available until recently. We have derived a time-series of the balances as a function of elevation, using original stake data from archived field notebooks and maps, graphs of balance as a function of elevation taken from old reports. We recalculate areally-averaged balances making adjustments for changes in hypsometry, considering the effect of different scenarios for internal accumulation and superimposed ice distributions. We find good agreement between the recalculated and original balances. We compare mass balance as a function of elevation to observed elevational changes, using the following sources: digitized topographic maps based on terrestrial or aerial photography (1936, 1962, 1969, 1977), a digital elevation model (DEM) constructed in a digital photogrammetric work station from 1995 aerial photographs, a DEM from a recent lidar campaign (2003), and differential GPS measurements made each spring (2003-2005). That the glacier overall is not in balance is evident from its continual retreat, which started early in the 1900s. Over the lower part of the glacier there is a significant difference between summed net balance and observed elevation change, which is attributed to flux gradients, rather than to errors. Average ice loss at the tongue is about 0.5 m a^-1. Elevations in the upper part of the glacier have until recently been more or less constant, within the error limits; over the last decade, however, there has been a decrease of about 0.5 m a^-1. The net balance record, while consistently negative, shows no significant short-term trends; however, the average annual decrease in volume appears to have accelerated over the last decade.
DE: 0720 Glaciers
DE: 1605 Abrupt/rapid climate change (4901, 8408)
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 1827 Glaciology (0736, 0776, 1863)
DE: 1863 Snow and ice (0736, 0738, 0776, 1827)
SC: Cryosphere [C]
MN: Fall Meeting 2005