Impact of the timing and duration of snow cover on ground surface temperature and active layer thermal regimes in Livingston and Deception islands (Maritime Antarctic)

A. FERREIRA; VIEIRA, G.; M. RAMOS; M.A. DE PABLO; GOYANES, G.

Núria

Congreso; IV Congreso Ibérico de la International Permafrost Association; 2013

Universitat de Barcelona

The thermal regime of the active layer and permafrost are largely controlled by ground thermophysical properties, water/ice content, topography, vegetation and very importantly, by snow cover thickness, rhythm and thermal characteristics. Deception and Livingston islands (South Shetland archipelago), are located in one of the regions on Earth where climate is changing faster, with mean annual air temperatures having increased over 2ºC since 1950. Current mean annual air temperature at sea-level are close to -2 ºC. Analysing data for active layer temperature evolution, snow thickness, and air temperatures allows for the characterization of energy exchange mechanisms between the ground and the atmosphere. In this poster, air and ground temperatures, as well as snow thickness data from 2009 and 2010 for Deception and Livingston islands are analysed. The coupling between the atmosphere and the ground is evaluated through the use of n-factor, which relates the air and ground surface thawing and freezing indexes. Altitude showed to be one of the most important factors controlling the spatial variation of snow and of ground surface temperature. The results in 2009 show that mean monthly snow thickness above 25 cm is sufficient to significantly insulate the ground from both winter freezing and spring thaw. The thawing season in the ground may be anticipated due to the lack of snow cover in some locations, while in others, delayed due to snow restricting coupling with the warmer atmosphere. Implications for the analysis of the ground surface and active layer thermal regimes are discussed.