Seasonal variation of Middle East jet stream and its thermal mechanism

Based on the annual average NCEP/NCAR reanalysis data, the seasonal variation characteristics of intensity and location of the Middle East jet stream (MEJS) and their relations with the South-North temperature differences (SNTD) are discovered. Results show that the intensity and location of MEJS have obvious seasonal variation characteristics. MEJS is stronger and locates in 27.5°N from November to the next April. MEJS is weaker from May to October and moves northeastward after May with its center maintaining over about 40°N from June to September. The seasonal variation characteristics of intensity and location of MEJS are significant with good corresponding relations to SNTD averaged from 500 to 200 hPa. It shows that the seasonal adjustment of SNTD has important effects on the seasonal variations of intensity and location of MEJS.