A model study of circum-arctic soil temperatures

A one-dimensional heat transfer model with phase change is applied to the entire Arctic terrestrial drainage area. The main forcing parameters are reanalysed surface air temperature that was topography-enhanced, and snow depth, derived from passive microwave satellite data. We present results based on daily fields of soil temperature, ranging from the soil surface down to 14 m depth. The horizontal grid cell resolution is 25 km x 25 km. Model results are compared to several long series of soil temperature measurements from Alaska and Siberia, with a relatively good match of the the annual cycle at different depths. We show time series of soil temperature at different depths for the 22-year period 1980 through 2001, and both seasonal and regional analyses are included. A trend analysis reveals positive trends for all permafrost regions in response to positive trends in air temperature, with the strongest warming trend in regions of continuous permafrost. A slight cooling trend is only found for the topmost soil layers in regions of seasonally frozen ground at the southern margins of the Arctic drainage domain. Copyright (C) 2004 John Wiley Sons, Ltd.