Аннотация:Necessity the snow cover to be accounted for in physical constructions describing large-scale climate processes is widely discussed in literature. However, attempts to incorporate snow cover in climate models face number of difficulties not only related to poor data availability. Difference between spatial/temporal scales of climate processes and those determining snow cover variability is one of the main problems in describing interrelation between snow cover and climate.
Practically all the effective physical properties of snow cover required by climate models are continuously reported to be determined by internal structure (stratigraphy) of snow cover. Despite recent progress in physical modeling of snow cover stratigraphy evolution, results of these models are not readily applicable to large-scale constructions. One-dimensional detailed models of snow cover evolution are comparable in complexity with GCMs, still representing only one geographical point of a snow-covered surface. Therefore, a hypothetic combination of such two types of mathematical models, theoretically allowing reconstruction of spatial and temporal variability of snow cover properties, cannot be validated and verified in principal by point observations even if data are available for a territory of interest and computer resources are sufficient. To resolve the problem, a modified snow cover classification, based on the previously constructed one (Sturm et al., 1995, J. Clim. 8(5) 1261-83) for a description of an averaged snow cover internal structure at the period of maximal snow accumulation at the scale of climatic zones is developed and becomes a part of snow parametrization in GCM of Hydrometcentre. Modification is related to description of an intraseasonal variability of the spatial distribution of the snow cover classes at continental scale in dependence on annual modeled variability of air temperature, precipitation and wind regime. Introduced spatial and temporal variability of snow cover properties is found to be of great importance for the climate model’s results.
The final goal of the investigation is construction of a tool allowing estimation of the snow cover role in not only heat and hydrological balances of large territories, but also in economy of the regions of interest. The work is supported by the INTAS project 03-51-5296.