Anomaly features of summer precipitation in eastern part of northwestern China and western Inner Mongolia.

This paper analyzed the spatial distribution and temporal change of the summer precipitation(Jun.to Aug.) in the eastern part of northwest China and western Inner Mongolia,using Mann-Kendall and Morlet,based on the monthly data of the summer precipitation from 64 representative weather stations during the period of 1961-2000,and compared the relationships between the summer precipitation and the data at NCEP/NCAR 500 hPa in the typical 5 years with high precipitation and the typical 5 years with low precipitation.The results indicated that there was a significant spatial difference of summer precipitation in the eastern part of northwest China and western Inner Mongolia,and the long-term overall trend of the summer precipitation in the eastern part of northwest China and western Inner Mongolia was increased at a rate of 2.3 mm per 10 years.The abrupt change of the summer precipitation occurred in 1976,and had the periods of 14-16 and 2-4 and quasi-5 years oscillations.There were negative anomaly fields of 500 hPa Height in high-precipitation years between the Baikal and northwestern China,the positive anomaly fields were over the coast of eastern Asia,and there were negative anomaly fields of 500 hPa Temperature in the Baikal,the zero-line was over the Eastern of northwestern China.The cold-air was to the northern region at 500 hPa Height anomaly field in low-precipitation years,there were positive anomaly fields between the Baikal and northwestern China,the negative anomaly fields were over the coast of eastern Asia,and there were positive anomaly fields of 500 hPa Temperature between the Baikal and northwestern China.