An optimized East Asian winter monsoon index and its circulation significance.

This paper demonstrates that the East Asian winter monsoon circulation index(EAWMI) IG is a circulation characteristic parameter that is significantly correlated with the intensity and meridional position of Mongolian high.Therefore it can be regarded essentially as the circulation index of the high.In a similar way to define IG,a group of optimized EAWMIs,IM,are constructed and optimally selected,and in comparison with IG,IM possesses advantages of simple structure,clear circulation meaning,more appropriately chosen definition gridpoints,and a closer correlation with winter temperatures in China.Because definition gridpoints of IM have a closer relation with Mongolian high,it can be called Mongolian high index.