Interdecadal Relation between Snow Cover over the Tibetan Plateau and Asian Monsoon Circulation

Based on the monthly mean snow depth observations over the Tibetan Plateau and the NCEP/NCAR reanalysis data,the relation between the obvious increasing of the Plateau snow cover and the transition of Asian monsoon circulation since the end of 1970s is analyzed.The results indicate that the increasing of winter or spring snow mass over the Plateau is mainly due to the enhance of the westerly south of the Plateau and the active westerly disturbances in winter and spring.The increasing of snow cover and the weakening of Asian summer monsoon both result from the transition of Asian monsoon circulation.Since the end of 1970s,the increasing of summer rainfall over East China and the decreasing of summer rainfall over South and North China are synchronous with the increasing of snow mass over the Plateau and the weakening of East Asian summer monsoon.The previous winter and spring snow cover over the Plateau positively correlated with the summer rainfall over East China and negatively correlated with the summer rainfall over South and North China on interdecadal time scale.Therefore,the researches about the relation between the Plateau snow cover and the summer rainfall over China should be set under the background of the interdecadal variation of Asian monsoon circulation.