Sensitivity of a distributed temperature-radiation index melt model based on AWS observations and surface energy balance fluxes, Hurd Peninsula glaciers, Livingston Island, Antarctica

U. Y. Jonsell,J. Otero,J. J. Lapazaran,F. J. Navarro,M. Bañón

doi:10.5194/tc-6-539-2012

U. Y. Jonsell, J. Otero + Show 3 more

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https://doi.org/10.5194/tc-6-539-2012

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Journal: The Cryosphere	Publication Date: May 21, 2012
Citations: 46	License type: CC BY 3.0

Affiliation: Agencia Estatal de Meteorología

Abstract

Abstract. We use an automatic weather station and surface mass balance dataset spanning four melt seasons collected on Hurd Peninsula Glaciers, South Shetland Islands, to investigate the point surface energy balance, to determine the absolute and relative contribution of the various energy fluxes acting on the glacier surface and to estimate the sensitivity of melt to ambient temperature changes. Long-wave incoming radiation is the main energy source for melt, while short-wave radiation is the most important flux controlling the variation of both seasonal and daily mean surface energy balance. Short-wave and long-wave radiation fluxes do, in general, balance each other, resulting in a high correspondence between daily mean net radiation flux and available melt energy flux. We calibrate a distributed melt model driven by air temperature and an expression for the incoming short-wave radiation. The model is calibrated with the data from one of the melt seasons and validated with the data of the three remaining seasons. The model results deviate at most 140 mm w.e. from the corresponding observations using the glaciological method. The model is very sensitive to changes in ambient temperature: a 0.5 °C increase results in 56 % higher melt rates.

Highlights

1.1 BackgroundRetreating and thinning glaciers have come into sharp focus in relation to increased atmospheric temperatures attributed to anthropogenic greenhouse emissions
We use an automatic weather station and surface mass balance dataset spanning four melt seasons collected on Hurd Peninsula Glaciers, South Shetland Islands, to investigate the point surface energy balance, to determine the absolute and relative contribution of the various energy fluxes acting on the glacier surface and to estimate the sensitivity of melt to ambient temperature changes
In this paper we present an automatic weather station (AWS) record extending over four melt seasons and its associated Surface energy balance (SEB) from a region scarcely represented in the literature, namely the Hurd Peninsula on Livingston Island, South Shetland Islands, an archipelago parallel to the northwestern extreme of the Antarctic Peninsula (AP) (Fig. 1)

Summary

Introduction

1.1 BackgroundRetreating and thinning glaciers have come into sharp focus in relation to increased atmospheric temperatures attributed to anthropogenic greenhouse emissions. As a prognostic tool for the response in energy fluxes, and eventually melt rates, to perturbations in meteorological conditions, SEB models have the advantage of being physically based but the disadvantage of involving a complicated extrapolation procedure to distribute the fluxes over the glacier surface (Hock, 2005). To overcome this complexity, simpler temperature-index models, based on the coupling between energy fluxes and temperature, are widely used. They perform best in environments where long-wave radiation and sensible heat are the dominating energy sources, as those fluxes are strongly coupled to temperature (Ohmura, 2001), while in environments dominated by solar radiation

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