Change of monsoon in Qinghai-Xizang Plateau and its correlation with summer precipitation of Ordos Plateau

Based on monthly reanalysis data of 600 hPa and 2.5°×2.5°ECMWF for period 1958 ~ 2002 and the data of summer precipitation in Ordos Plateau during 1961~2000,Qinghai-Xizang plateau monsoon index series indicating monsoon characters in Qing-Xizang plateau was calculated,changes of monsoon in Qinghai-Xizang plateau and its correlation with summer precipitation in Ordos Plateau were analyzed.In recent 40 years,the change of Qinghai-Xizang plateau monsoon index appeared decrease in winter and increase in summer,and the change related closely to the summer precipitation of Ordos Plateau.In the years with strong winter monsoon in Qinghai-Xizang plateau there was more summer precipitation in Ordos Plateau,and vice versa.