10──20天准双周振荡的经向传播及地理特征

The Longitudinal Propagations and Geographical Features of the 10-20 Day Oscillation

本文采用ＥＣＭＷＦ１９８３年７月１日至９月１２日逐日２００ｈＰａ纬向风场资料，用复经验正交方法讨论了１０－２０天低频振荡的经向传播及地理特征。结果表明：（１）１０－－２天振荡有三个显著区域：贝加尔湖附近地区；赤道９０°Ｅ附近以及新加坡、马来西亚地区；８０－１００°Ｅ，２２－３２°Ｎ之间。（２）源于较高纬度地区的振荡与源于赤道附近地区的振荡在１０５°Ｅ，１７—２３°Ｎ附近同位相相遇，在９０°Ｅ，２０°Ｎ附近反位相相叠加，振荡相互削弱，在２５°Ｎ附近同位相相遇。（３）从振荡位相来看，中南半岛东南部、马来西亚北部、菲律宾以西区域的振荡向北传播到中国东南沿海，向西传播到孟加拉湾印度半岛；２０°Ｎ以南低纬度地区的振荡很少能传播到８０°Ｅ以东３０°Ｎ附近地区；位于９０－９５°Ｅ，２５－２７°Ｎ之间的振荡以及贝加尔湖附近地区的振荡可以向南北两个方向传播。

By using complex empirical orthogonal function (CEOF), the longitudinal propagations and geographical features of the 10-20 day low-frequency oscillations have been discussed with the data of the daily 200 hPa ECMWF zonal wind data from July 1 to September 12, 1983.From the study we can reach the following conclusions: (1) The 10-20 day low-frequency oscillations occur in three regions, i.e., the Lake Balkal region, the region in the equator near 90°E and Singapore, Malaysia, and the region of 22°N to 32°N, 80°E to 100°E. (2) The oSCillation originated from higher latitude regions and the oscillation originated from the equator region meet in phase in the region between 17°N and 23°N around 105°E, and the oscillation superposes out-of-phase near 20°N around 90°E, with the oscillation weakened. (3) The oscillation originated in northern Malaysia and the western Philippines propagates northward to the southeast coast of China and propagates westward to the Bay of Bengal-India. The oscillation originated in regions south to 20°N rarely propagates northward to the region east to 80°E around 30°N. The oscillation originated in region of 25°N to 27°N, 90°E to 95°E can propagate both northward and southward, and so does the oscillation originated in the Lake Baikal region.