Regime térmico da camada ativa na Península Keller, Ilha Rei George, Antártica (2008-2011): contribuição ao monitoramento de ambientes periglaciais

Abstract

The thermal regime of active layer above the permafrost is an effective indicator of climate change effects in periglacial environments, because soil does interface with atmosphere and terrestrial biota, that justify it monitoring. This study objectived to analyze the active layer thermal regime in six monitoring sites localized on Keller Peninsula, King George Island, Maritime Antarctica. Temperature and moisture sensors were installed at different soil depths, making a continuous data series since February-March/2008 until January-February/2011. Cluster dendrogram was used to an exploratory data analysis of soil temperature in sites. The main feature that defined the groups was the occurrence of thermal isolation caused by snow or vegetation. The active layer thickness and permafrost depth were estimated for each site by regression. Thermal diffusivity through soil profile was estimated using the parameters obtained in model adjustment for soil temperature. Soil properties that influence the diffusivity were organic matter and texture. Soils with more clay or organic matter had a minor thermal diffusivity. Thermal diffusivity increased with soil depth and is related to soil water content. There was a displacement in temperature freezing point of soil water, and this displacement was greater in soils with higher salt content. Time series analysis showed periods of more frequency: annual and intra-annual (seasons). There was a between annual period with significant frequency that can be associated with the South Annular Mode (SAM), climatic mode that occurred in the region during the study period.