Based on NCEP/NCAR monthly reanalysis data, the elements of the circulation field over the Qinghai-Xizang Plateau in winter and summer in P, Z and σ coordinate systems were analyzed, got the main distribution field of plateau monsoon, and drew a conclusion that the divergence field can most effectively reflect plateau monsoon' s characteristics in the troposphere.Based on regional average of divergence field in the center of plateau main body, a new plateau monsoon index Div-PMI was defined.By contrasting the Div-PMI versus 4 kinds of plateau monsoon index on computing method, physical significance, seasonal and interannual variation, it was found that Div-PMI has a simple calculation method, can also reflect plateau monsoon' s production mechanism preferably.Besides, it has a preponderance on reflecting the characteristics of the plateau monsoon's seasonal variation.A correlation analysis was made between monsoon index and the monthly precipitation of January, April, July and October in China, it was discovered that Div-PMI has a negative correlation with plateau area precipitation and the correlation is most remarkable in all indexes.
Plateau monsoonPlateau monsoon indexDivergence field
NETL
NSTL
维普
万方数据
