A PRELIMINARY STUDY ON THE HISTORICAL OSCILATION OF THE CIRCULATION OVER THE FAR EAST AND THE NORTH-WESTERN PACIFIC

Herein a new type of air circulation indices is designed, i.e., Iω, the regional index of west wind and IS, the regional index of South wind. They are the algebraic sum of net air mass transfer on the opposite boundaries of the studying area, respectively. Using these as a tool, the historical oscillation of air circulation of the Far East and the Northwestern Pacific area(20-60°N, 105-180°E) for the period from 1873 to 1960 is analyzed. In the first or 3 decades of the referring period, as depicted in table 3, the air circulation was abnormally intensive both in winter and summer. In the succeeding 30 years, the air circulation slackened all the year round, while the eastern component flew in greater abnormality, in comparing with the winds from other directions. Finally, in the last 3 decades, the dominant directions turned to northerly in winter, and westerly or southwesterly in summer, meanwhile air mass transfer increased considerably in the zonal as well as in the meridional direction. As to the recent ten years, the circulation in the studied area seems to slow down again. Comparing with Lee's data of indices, calculated by the A. L. Kats's method, and referring to the general trend of climatic changes worked out by some authors of corresponding period, the above analysis is proved to be real and the newly suggested indices to be physically sound.