Climatic relationships of permafrost zones in areas of low winter snow-cover.

Abstract

In areas with under 50cm snow cover in winter, the permafrost zones are defined by the freezing indices and thawing indices. The warmer boundary of the zone of continuous permafrost traverses the mean annual air temperature (MAAT). The boundary between discontinuous and sporadic permafrost lies just on the cold side of 0oC MAAT. The sporadic permafrost zone includes the zone of ice caves and the regions with patches of ice beneath ponds and peatbogs, out to 5oC MAAT at a thawing index of 4000 degree days per year. The relationship works for Norway, Iceland, Spitsbergen, Canada and the People's Republic of Mongolia. Variations in lapse rate indicate that calculations of past world climatic change based on data from one area will be difficult. - from Author