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上海地处长江三角洲冲积平原,由于沿江滨海,水网交错,在特定的环流形势背景下,可在市区形成集中降水。本文针对1985年8月31日(以下简称8.31)发生于上海的一次特大暴雨,在对环流形势分析的基础上,进行气流升速等7个物理量的计算,研究了下垫面对局地强雷暴活动的动力、热力和地形作用。结果表明:南下的冷空气与太平洋副热带高压西缘暖湿气流的辐合是造成这次雷暴雨的发生源,而在副高短期稳定,西风槽少动的条件下,海风锋和城市热岛可对最大降水落区起到触发机制或“诱导”、增幅作用。
Shanghai is located in the alluvial plain of the Yangtze River Delta. Due to the coastal seashore and water networks staggered along the river, Shanghai can form a concentrated rainfall in the urban area under the circumstance of specific circulation. In this paper, a heavy rainstorm occurred in Shanghai on August 31, 1985 (hereinafter referred to as 8.31), based on the analysis of the circulation situation, the calculation of seven physical quantities such as the velocity of gas flow was conducted. Thunderstorm activity, heat and topography. The results show that the convergence of the warm air between the cold air in the south and the western margin of the Pacific subtropical high is the source of this thunderstorm. Under the short-term stability of the subtropical high and the weak movement of the westerly trough, Trigger mechanism or “induce” and increase effect on the area of maximum precipitation drop.