王時鼎

Characteristics of the Upper Air Wave Disturbances over Asia as Revealed by Synoptic and Statistical Analysis

Shih-Ting Wang

Abstract

　　This report is the third part of the study of the upper air circulation and wave disturbances. The first part is “the upper air circulation in Asia” and the second part is “the nature of the orographic disturbances caused by the Tibetan Plateau”.In the present study, five topics are emphasized. However, here only the third topic is presented.

　　In this study we examined the sector circulation index (S.C.I) for the upper air flows, the influences of seasonal changes in heat source and sink on the upper air circulation, the preferred location for the formation and development of upper disturbances, the characteristics of waves of numbers 4-7 in winter, the dominat forcing factors of upper air wave disturbances in Asia, and physical mechanism of the Eurasian upper air flow patterns.

　　The principal results we found are that:

(1) classification of upper wave disturbances is possible by the S C.I. designed for this area.

(2) the differential heating caused by orography in Asia plays acompletly different role to the Asian circuiation patterns in autumn and spring seasons.

(3) the seasonal variation of the preferred regions for formation and development of upper waves are well ducumented by specially designed time cross section diagram.

(4) three principal physical mechenisms for upper wave disturbances in Asia are to be found, i.e; the blocking and deflecting effects of the Tibetan Plateau, and the cycle of the S.C.I.