Numerical Experiments for the Influence of the Surface Drag Effect of the Qinghai Xizang Plateau on the General Circulation in Spring

This long-range numerical experiments for the influence of the surface drag effect of the Qinghai-Xizang Plateau on the general circulation in spring by using a CCM1 (R15L7) –LNWP model based on CCM1 (R15L12) are carried out. The results show that the prediction results can be improved when difference of the mean monthly drag coefficient between Qinghai Xizang Plateau and other land areas increases from 0.0008 to 0.004. The surface drag effect of the Plateau is advantageous to the increasing of the temperature over the Plateau and the decreasing at the north of the Plateau, which induce to the enhancing of the westerly wind in the upper levels over the Plateau and its north side, and the weakening centers of the westerly appear on the south side of the Plateau, which are favorable to the northward shift of the southern subtropical westerly jet in East Asia. It is also beneficial to the enhancement of the Northern Hemispheric three-circle and global meridional circulation.