CHARACTERISTICS OF ZONAL PROPAGATION OF ATMOSPHERIC KINETIC ENERGY AT EQUATORIAL REGION IN ASIA

Based on the daily NCEP/NCAR reanalysis dataset from 1980 to 1997, the zonal propagation of 850 hPa kinetic energy ( K ) and meridional wind ( v ) at the equatorial region averaged at (0°-5°N) are examined respectively. Results show that the strongest center of K in the tropical Asian summer monsoon region locates over 75°-90°E, with the secondary over Somalia low level jet channel, i.e., about 50°E. East to 90°E, disturbances of both K and v are observed mainly coming from the western Pacific Ocean and propagating westward to the Bay of Bengal passing through the South China Sea. But the propagation directions of both K and v are rather disorderly between the Bay of Bengal and the Somalia low level jet channel. Therefore, the East Asian summer monsoon and the Indian summer monsoon are different in the propagation features of the disturbances of K and v. Above facts indicate that, East Asian monsoon system exists undoubtedly even at the equatorial region, and quite distinct from the Indian monsoon system, it is mainly affected by the disturbances coming from the tropical western Pacific rather than from the Indian monsoon region. The boundary of the two monsoon systems is around 95°-100°E, which is more westward than the counterpart as proposed in earlier studies by 5-10 degrees in longitude.