南海低压倾斜结构的特征分析

ANALYSIS ON FEATURES OF SLANT STRUCTURE OF TROPICAL DEPRESSION IN SOUTH CHINA SEA

南海低压的中心在垂直方向上常发生倾斜,高低层的环流中心出现明显错位。如果预报员只关注卫星云图的云团动态,往往会得到低压中层环流中心的错误信息,使预报失败。因此对南海低压的预报更需要关注其低层环流的动态,特别在云团或风速极不对称致使低压环流可能出现转向时,或靠近陆地时都会出现云团和低层环流明显的倾斜,使南海低压的路径(特别是靠岸时)更复杂多变,需要谨慎分析各种资料信息,综合判断才能作出准确的预报。本文的工作旨在为南海低压的预报提供一些经验参考。

In South China Sea, centers of tropical depressions often slant along the perpendicular direction. The center of lower circulation is obviously inconsistent with that of upper circulation. As for a forecaster, too much concern about the cloud cluster itself on a satellite image will often cause an incorrect judgement and lead to a failure of forecast. Its necessary for forecasters to pay more attentions to the changes of the lower circulation, especially when the cloud cluster or the wind speed appear to be extremely asymmetrical, which may cause the low pressure circulation to change its direction or an obviously dynamic inconsistency when approaching the coast. These are some features of the complexity of the South China Sea TC. To make out a satisfying forecast, comprehensive and careful analysis on varieties of information is needed. This article is to share some experience in dealing with this type of tropical depression in the South China Sea, hoping that it can offer some reference.