The main aim of the present work is to create the dynamics- stochastic model of soil freezing that combine the determinism of physical processes and stochastic spatial structure of snow pack and heat-physics soil properties. Such models are needed for estimation characteristics of soil freezing at mesoscale inhomogeneous objects: administrative area, cell of the grid of the atmosphere global circulation models, etc.
To reach this aim it was necessary to solve the following tasks: (i) to select patch-oriented soil freezing model which must be the base of the corresponding dynamics stochastic model; (ii) to find the statistics of the main factors determining dynamics and spatial variability of soil freezing depth; (iii) to modify the patch-oriented soil freezing depth, that described soil freezing dynamics at small homogeneous site, to corresponding dynamics-stochastic model, that described soil freezing at mesoscale inhomogeneous object.
As local-oriented model it was used the soil freezing model of one of the authors of the present work (Gusev, 1993). The main factors determining the spatial variability of soil freezing in this model are the snow high h, soil thermal conductivity and soil moisture W. Herewith, the variability of soil thermal conductivity is determined in mainly by the variability of soil moisture. Thus, it was necessary to have the statistics of spatial distribution of h and W. These statistics for objects of different spatial scale were obtained on the base of our researches and observation data of water balance stations in the foreststeppe zone of European part of the Former Soviet Union.
The dynamics-stochastic model of soil freezing depth was created with orientation on the statistics of h and W. This model allows to calculate the dynamics of the average soil freezing depth for selected object, its standard deviation and its distribution function. The comparison of these simulated characteristics with observation data of Nizhnedevitskaya water balance and Kursk biosphere station indicated satisfactory agreement.
References
Institute of Water Problems Russian Academy of Sciences Novobasmannaya st.10, Box 524 107078 Moscow, Russia Tel: (095) 265-95-85 E-mail: gusev@iwapr.msk.su