Southern Hemisphere mean zonal wind in upper troposphere and East Asian summer monsoon circulation

Abstract

Rlationship between the Southern Hemisphere upper troposphere zonal wind variability and the East Asian summer monsoon was studied. The mean zonal wind difference in 150 hPa between 60°S and 30°S is defined as an index (ISH). The research reveals that ISH is negatively correlated with the East Asian summer monsoon (EASM) circulation in the interannual scale. It is also suggested that the meridional teleconnection in the zonal wind field, with the main part in Eastern Hemisphere, from mid-and-high latitudes in the Southern Hemisphere to the tropical region is responsible for the ISH-EASM link-age. The teleconnection may result in changes of the wind fields and pressure system changes causing variability of the East Asian monsoon. In addition, the anomalous teleconnection pattern in Eurasia is likely to be another mechanism. ISH and EASM circulation are found to have both simultaneous and lag correlations, thus, the relationship has implications for seasonal climate prediction over East Asia.