Parameterization of cold-season processes in the MAPS land-surface scheme

A coupled atmospheric/land-surface model covering the conterminous United S tates with an associated 1-hour atmospheric data assimilation cycle, the Me soscale Analysis and Prediction System (MAPS), has been improved to include a snow accumulation/melting scheme and also parameterization of processes in frozen soil. The new aspects of the land-surface model are described in this paper, along with detailed one-dimensional (1-D) tests using an 18-yea r observation data set from Valday, Russia, These tests show that the MAPS 1-D soil/vegetation/snow model is capable of providing accurate simulations over multiyear periods at locations with significant snow cover and frozen soil. A statistical analysis of the tests shows the expected improvement i n snow depth, skin temperature, and especially in runoff from inclusion of these additional surface processes during the spring melting season. This p erformance in 1-D tests is a necessary prerequisite for robust long-term be havior of soil temperature and moisture fields and other components of the hydrological cycle in the 3-D MAPS coupled assimilation cycle.