A Numerical Investigation of Thermal Dynamics of Permafrost in Northern Eurasia

Soil temperature is a crucial component of land surface processes and a sensitive indicator of climate changes in the Arctic. Soil thermal condition determines the distribution of permafrost and active layer, which are both extremely vulnerable to climate change and have great impacts on the energy, water, and chemical processes on the land surface. Recent studies have shown a general rise of soil temperature and degradation of permafrost due to climate warming in the Northern Hemisphere during the 20th century. However, most observationally based studies are usually limited by a lack of observing stations. Numerical modeling, on the other hand, can provide a better way of reproducing the physical, biological, and chemical processes in cold regions where there are sparse observations. Further, it allows the coupling of these processes to investigate the interactions between the land surface and the atmosphere. In this study, the Variable Infiltration Capacity (VIC) land surface model is used to simulate the spatio-temporal distribution of soil temperature in Russia. Meteorological forcing data are obtained from a global daily meteorological dataset with 1.0 degree resolution. Vegetation and soil parameters for each grid cell are derived from Land Data Assimilation Systems (LDAS) and Harmonized World Soil Database (HWSD), respectively. Historical soil temperature observations at 423 stations are used for model validation. This study thus provides validated gridded fields of soil temperatures, continuous in both time and space, which provide for a better understanding of frozen ground distribution and changes under climate warming in Russia.