Water and Heat Budget in southwest China influence East Asian Climate

The regional climatic effects of land cover change in Guizhou Karst Plateau (GKP) were investigated using the WRF model. The WRF showed high ability to downscale NCEP-DOE Reanalysis-2, especially for the precipitation simulation. After land degradation over GKP, the net radiation and evaporation were reduced mainly within the desertification area, consistent with the reduction in rainfall and the increase in surface temperature there. The southwest monsoon flow from the Bay of Bengal was weakened over the adjacent area to the northeast, influencing the East Asian summer monsoon. Meanwhile, the weaker low-layer anti-cyclone and the stronger horizontal convergence enhanced the vertical motion in the southeastern coastal areas. Furthermore, owing to the decreased surface heating in the degradation experiment, the lifting over GKP and neighboring regions to the east was limited, which resulted in the reduced rainfall within GKP and strengthened the ascending motion downstream over 114°-122°E. Such circulation differences favored the increase in moisture flux and clouds, and thereby caused more precipitation in China southeast coastal areas.