Characteristics of South Asia High in Summer in 2010 and Its Relationship with Rainbands in China

Abstract

The characteristics of the South Asia high (SAH) and subtropical westerly jets in the summer of 2010 and their relationship with the changes in rainband in China were analyzed. As shown by the results, the SAH in the upper troposphere extended northward relatively late in June 2010. Correspondingly, the subtropical westerly jets on the north side of the SAH jumped northward comparatively late, thus delaying the formation of a strong divergence field in the upper air over the Yangtze-Huaihe River valley. This was one of the main causes for the late onset of plum rains in the Yangtze-Huaihe River valley. In July, there was a vertical structure consisting of upper-level divergence and low-level convergence near the subtropical westerly jets on the north side of the SAH and in the air stream dispersal area on the northeast side of the eastward-extending SAH, which was the dynamic mechanism bringing about frequent and extremely heavy rainstorms during the plum rain period in this year. The SAH in the upper troposphere affected the subtropical high in the lower stratosphere, and thereby led to changes in the main rainband location in China.