VARIABILITY IN OCCURRENCE OF CHINA’S SPRING SAND/DUST STORM AND ITS RELATIONSHIP WITH ATMOSPHERIC GENERAL CIRCULATION^*

Spatial distribution and climate variability of China's spring sand/dust storms,and their association with the atmospheric circulation patterns at 500 hPa in the present spring and previous winter were researched in this study.The result shows that in China more than 50 percent of sand/dust storms are observed in spring,especially in Northwest China,where sand/dust storms occur frequently.The occurrence of China's spring sand/dust storms has a general decrease trend in the past 50 years,but it has tended to increase again since 1997.There are significant differences in the general circulations between the most frequent and the least frequent sand/dust storm springs.During the spring and previous winter of the most frequent sand/dust storm springs,at 500 hPa,positive anomalies were found over the Mt.Ural,while negative anomalies were over Siberia and Mongolia.During the least frequent sand/dust storm springs,however, there are negative anomalies over the Mt.Ural and positive anomalies over Europe,Siberia and Mongolia.