“三带”天气系统交会和引潮力共振对华北特大暴雨形成的影响

Influence of the Meeting of Three Belts' Synoptic Systems and Tide-Forming Force Resonance on the Exceptionally Serious Rainstorm in North China

分析、研究华北和邻近的辽宁地区曾发生过的“５８．７”、“６３．８”、“７５．８”和“３０．８”等４次罕见特大暴雨，结果表明，它们的气象学成因都是由于热带、副热带、西风带三种不同性质的天气系统的特定配置，引起暖湿气流和干冷气流在本区交绥所致。而这些天气系统的特定配置又与引潮力共振的特定迭加有密切联系。尤其是在暴雨天气形势具备之后，如果华北继续遇引潮力共振减压的迭加，将触发罕见特大暴雨的发生。其中台风在影响本区时（假定台风登陆我国大陆时强度为３５ｍ／ｓ），如遇一个引潮力共振减压，当天的最大日降水可达５００ｍｍ左右；如一天内遇两个引潮力共振减压的迭加，则当天的最大日降水将达１０００ｍｍ左右。

Four exceptionally serious rainstorm events occured in North China and Liaoning Province, namely the '58.7','63.8','75.8' and '30.8' rains. With a review of their meteorological background and possible causes, this paper points out that the specific disposition of three different synoptic systems of tropical, subtropical and westerly belts causes the meeting of the air current of warm-wet and cold-dry in this area, and this kind of disPOsition of the synoptic systems is closely related to the specific superposition of tide-forming force resonance. Especially, if the rainstorm synoptic situation dominates in North China, with a continuously meeting of the superposition of pressure decrease of tide-forming force resonance, it can tfigger off an exceptionally serious rainstorm. Concret6iy, when a typhoon affects this area (assuming that the typhoon nit6nsity is 35m/s at landing the Chinese Continent), the daily maximum rainfall could reached about 500mm if the pressure decrease of one tideforming force resonance occures, and the daily maximum rainfall could reached about 1,000 mm if the superposition of pressure decrease of tWo tide-forming force resonance occures during the period of a day.