Snowmelt modelling on Signy Island, South Orkney Islands

The ability of the Utah energy-balance and snowmelt model (UEB) to simulate decline in snow water equivalent (S"'E) at an extreme location was assessed. Field data were collected at Paternoster Valley, Signy Island, South Orkney Islands (60°43' S) during the austral summer of 1996-97. This is the first application of UEB in a maritime Antarctic site. UEB is a physically based snowmelt model using a lumped snowpack representation with primary state variables SvVE and snowpack-energy content (U). Meteorological inputs are air temperature, wind speed, humidity, precipitation and total incoming solar and longwave radiation. The Paternoster Valley catchment was subdivided into eight non-contiguous terrain classes for sampling and modelling using a geographical information system (GIS). Simulations of SWE in each of these classes were compared with field observations. It is shown that initial U and snow-surface thermal conductance (Ks) affect model simulations. Good approximations of SWE depletion are obtained using measured incoming solar radiation to drive the model but there are shortcomings in the characterization of longwave radiation and sensible-heat fluxes.

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