HR: 1340h
AN: C23A-0977    [Abstracts]
TI: Modelling the Re-freezing of Surface Meltwater and the Formation of Superimposed Ice on an Arctic Glacier
AU: * Wright, A
EM: A.P.Wright@bristol.ac.uk
AF: Bristol Glaciology Centre, School of Geographical Sciences, University Road, Bristol, BS8 1SS United Kingdom
AU: Wadham, J
EM: J.L.Wadham@bristol.ac.uk
AF: Bristol Glaciology Centre, School of Geographical Sciences, University Road, Bristol, BS8 1SS United Kingdom
AU: Siegert, M
EM: M.J.Siegert@bristol.ac.uk
AF: Bristol Glaciology Centre, School of Geographical Sciences, University Road, Bristol, BS8 1SS United Kingdom
AU: Luckman, A
EM: A.Luckman@Swansea.ac.uk
AF: Department of Geography, University of Wales Swansea, Singleton Park,, Swansea, SA2 8PP United Kingdom
AU: Kohler, J
EM: jack.kohler@npolar.no
AF: Norwegian Polar Institute, Polar Environmental Centre, Tromso, N-9296 Norway
AB: A detailed surface energy-mass balance model including an explicit calculation of meltwater refreezing and superimposed ice formation is run with meteorological input from the past 30 years at Midre Lov‚nbreen - a high Arctic valley glacier, Spitsbergen, Svalbard. The model is then validated through comparison of the results with field measurements and observations. Further comparisons are then drawn between the results of this physically based model and those of simpler, more easily applicable models of refreezing both new and taken from the literature. Model results indicate that superimposed ice alone accounts for 33 % (on average) of the total net accumulation at Midre Lov‚nbreen under present conditions. Correspondingly the removal of all forms of meltwater refreezing from the mass balance calculation is shown to result in a 68 % increase in the rate of modelled mass loss from this glacier. Net mass balance output from the coupled model is found to be highly sensitive to changes in mean annual air temperature but much less sensitive to changes in annual precipitation. The detailed model presented here closely reproduces the field measurements of superimposed ice. The simpler models, however, vary in their agreement to the field data, with highly schematic approaches found to transfer poorly from the conditions under which they were developed. An additional scheme is therefore presented here based on a simplified thermodynamic approach to calculating the mass of meltwater refreezing at any site. This requires only annual climatic input data, yet is transferable to a range of conditions due to the physical basis of the calculation.
DE: 1827 Glaciology (1863)
DE: 1863 Snow and ice (1827)
SC: Cryosphere [C]
MN: 2004 AGU Fall Meeting