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REVIEWS OF GEOPHYSICS, VOL. 43, RG4002, doi:10.1029/2004RG000157, 2005

Influence of the seasonal snow cover on the ground thermal regime: An overview

Tingjun Zhang

National Snow and Ice Data Center, Cooperative Institute for Research in Environmental Sciences University of Colorado, Boulder, Colorado, USA


Abstract

The presence of seasonal snow cover during the cold season of the annual air temperature cycle has significant influence on the ground thermal regime in cold regions. Snow has high albedo and emissivity that cool the snow surface, high absorptivity that tends to warm the snow surface, low thermal conductivity so that a snow layer acts as an insulator, and high latent heat due to snowmelt that is a heat sink. The overall impact of snow cover on the ground thermal regime depends on the timing, duration, accumulation, and melting processes of seasonal snow cover; density, structure, and thickness of seasonal snow cover; and interactions of snow cover with micrometeorological conditions, local microrelief, vegetation, and the geographical locations. Over different timescales either the cooling or warming impact of seasonal snow cover may dominate. In the continuous permafrost regions, impact of seasonal snow cover can result in an increase of the mean annual ground and permafrost surface temperature by several degrees, whereas in discontinuous and sporadic permafrost regions the absence of seasonal snow cover may be a key factor for permafrost development. In seasonally frozen ground regions, snow cover can substantially reduce the seasonal freezing depth. However, the influence of seasonal snow cover on seasonally frozen ground has received relatively little attention, and further study is needed. Ground surface temperatures, reconstructed from deep borehole temperature gradients, have increased by up to 4°C in the past centuries and have been widely used as evidence of paleoclimate change. However, changes in air temperature alone cannot account for the changes in ground temperatures. Changes in seasonal snow conditions might have significantly contributed to the ground surface temperature increase. The influence of seasonal snow cover on soil temperature, soil freezing and thawing processes, and permafrost has considerable impact on carbon exchange between the atmosphere and the ground and on the hydrological cycle in cold regions/cold seasons.

Received 21 July 2004; accepted 17 November 2005; published 31 December 2005.

Keywords: frozen ground; permafrost; snow cover; soil temperature.

Index Terms: 0736 Cryosphere: Snow (1827, 1863); 0704 Cryosphere: Seasonally frozen ground; 0702 Cryosphere: Permafrost (0475); 1863 Hydrology: Snow and ice (0736, 0738, 0776, 1827); 1866 Hydrology: Soil moisture.

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Citation: Zhang, T. (2005), Influence of the seasonal snow cover on the ground thermal regime: An overview, Rev. Geophys., 43, RG4002, doi:10.1029/2004RG000157.