大气中的降水与反降水──' 98梅雨锋暴雨的天气学成因分析与预报探讨

THE PRECIPITATION AND ITS INVERSE PRECIPITATION OF THE ATMOSPHERE ──Analysis of the synoptic cause of '98 Mei-yu Front's rain gust and study of its prediction

对我国T106L19(客观分析)模式大气(1998年6～7月)做了大气中所有天气学降水(垂直运动形式)的计算。研究表明,' 98长江流域上空暴雨存在着明显的梅雨锋天气(尺度)系统降水,同时,长时间湿空气团的维持及其输运,和在梅雨锋上的非等熵湿绝热运动并不断形成对流不稳定降水,是强降水发生的天气学成因。因此,用模式大气中各种天气学形式的降水去(概率)统计预报实际大气降水,实现了预报因子和预报对象之间数学(统计)意义上的线性化。且表明它们可为统计预报(包括Kalman滤波)提供有明确(直接)降水天气学意义的连续的预报因子(场)。

With the isentropic coordinates system we have calculated many synoptic types (perpendicular motion) of precipitation of the (objective analysis) model atmosphere of T106L19 in June and July 1998. Two types of synoptic (scale) precipitation are condensation function and moisture flux divergence that have their positive and negative distributions and are both continuous "waves" (called precipitation and inverse precipitation). There are two more types of a mass moist-unstable precipitation and an air layer moist convection precipitation in the atmosphere,which have their selective-random characters. This paper has made it known that there will be two above-mentioned types of Mei-yu Front's precipitation above the Yangtze River's basin. And the moist air masses maintain long time and transport rapidly, and the non-isentropic saturation-adiabatic process comes into being moist convection precipitation, that is the synoptic causes of the rain gust. Therefore, with a few factors of precipitation of the forecast model atmosphere, which are continuous fields, it has been possible to forecast actual precipitation of real atmosphere with statistical & probable method (include Kalman filter). So linearization on statistics between the predictors and the predicated has come true in fact.