Model package COLD describes the processes of formation of soil heat and water regime in cold season. It combines three independent analytical models developed by Ye.M.Gusev (1993): model FRED (FREezing Depth) which describes soil freezing under snow cover (with water influx from the underlying unfrozen zone) occurring from the moment when air temperature falls below zero (in autumn) till the beginning of snow melting (in spring); SOT (SOil Temperature) for simulating the heat regime of soil before snow melting and for calculating vertical profile of soil temperature and MIR (Melting, Infiltration, Runoff) describing snow melting with subsequent infiltration and surface runoff. COLD prepares the input for model VAST (Vegetation-Atmosphere-Soil Transfer scheme) describing the processes of heat and water exchange within a soil-vegetation-atmosphere system in warm season. The input represents the value of spring water stores Vs in the uppermost 1 m soil layer. That is why COLD was validated with respect to Vs using standard records of agrometeorological station Petrinka (the Kursk region, Russia) from 1955 to 1988 and materials of the Central-Chernozem State forest-steppe reserve from 1955 to 1973. Comparison of simulated values of soil water stores with values measured in various ecosystems (deciduous forest, steppe, grassland, fallow, agricultural fields) shows a good agreement. After that, COLD was connected with model VAST into a package ANDY_SWASH (ANnual DYnamics of Soil WAter Stores for Homogeneous areas). ANDY_SWASH was also validated against water stores in 1 m soil layer using the above mentioned data. Analysis of the obtained results shows that COLD is suitable for calculating annual dynamics of soil water stores in different agroecosystems.
Olga N. Nasonova Institute of Water Problems, Russian Academy of Sciences, Novobasmannaya st.10, Box 524, 107078 Moscow, Russia Telephone: (095) 265-95-85