A Preliminary Analysis of the Cross-Equatorial Flows During the Northern Winter Monsoon

By using the grid wind data from 1980 to 1986, the eastern Hemisphere cross-equatorial flow channels in the lower and upper troposphere during the Northern winter monsoon (Dec.—Feb.) are investigated. It is found that there are five channels in the lower troposphere in the region mentioned above. They are located at 105°E, 125°E, 45°E, 80°E and 150°E, respectively, with the main zone between 100°E and 130°E. In the upper troposphere, the main channels of the cross-equatorial flows are located in the region of 80°―120°E. During both winters of 1983―1984 and 1984―1985, it is found that there exists a strong cross-equatorial flow from north at the channel of 45°E, which is associated with the persistent high-latitude blocking pattern occurred at 500 hPa over the eastern Atlantic Ocean and also with the more frequent genesis of the tropical storm over the southern Indian Ocean and southern Pacific Ocean. Additionally, the analyses of the mean meridional cell indicate that there is a complete winter monsoon circulation in the region of 80°―125°E during the Northern winter monsoon