Numerical Simulation of Climate Variance with the Land Surface Change over Sanjiang Plain

The climate characteristics in June and July over Sanjiang Plain from 1950 to 1955 and from 1996 to 2000 are simulated by using the regional climate model RegCM3, and underlying land surface type data used in this study are modified by TM data. The results show that the modified data can present the land surface conditions well in different periods. The area of marsh induced, and the wetland was substituted by farmland especially in the northeast and the southeast of the palin. The surface air temperature rises from 1950s to 1990s, and the surface ground temperature rises in north and northeast of the plain because of the change of the land surface. The net short wave flux in the land surface increases more than 40w/m2. The simulated recipitation in June over the Sanjiang Plain decreases, and the precipitation in July increases, which is accordant with observation. Analysis of evaporation, precipitation, runoff and soil water shows that it is much warmer and drier in 1990s than in 1950s in the west of plain. Soil water content has obviously reduced in 1990s, especially in the west and north of plain, where most of marsh has turned into cropland.