Spatial Structure of East Asia Subtropical Jet Stream and Its Relation with Winter Air Temperature in China

The spatial structure of the East Asia jet (EAJ) and its relation to the winter temperature in China is analyzed by using NCEP/NCAR monthly reanalysis data from 1950 to 2012 and daily air temperature data from 542 station in China. The results show that the subtropical jet is divided into tubular and irregular structures. The jet's volume becomes largest in winter, and its vertical thickness ranges from 500 hPa to 100 hPa. In summer, the jet was just visible at 200 hPa, and its volume was smallest. The jet tube runs from southwest to northeast in autumn, winter, and spring but from west to east in summer. The meridional movement of the mean axes, which represents the greatest wind speed from 500 hPa to 100 hPa, is not synchronous. The wind axes at low levels are always north of the high ones in spring and autumn. The vertical motions below each part of the EAJ differ and vary seasonally. In addition, the strength of the winter EAJ, especially the middle part, is correlated with the winter temperature in China. When the middle part of the EAJ is strong, the winter temperature in most parts of China might be low.