关键词: 对流性暴雨, 中β尺度低压, 列车效应, 概念模型

Abstract: Based on multi-observational data and NCEP reanalysis data (1°×1°), a disperse convective rainstorm occurring in Henan Province on August 1, 2019 was analyzed. The results are as follows：(1) The confluence of warm and humid southwest air flow on the edge of the subtropical high and the cold air carried by westerly trough over Henan Province and the strong dynamic effect of upper level jet provided a large scale circulation background for this process. (2) There existed strong convective potential before occurrence of the rainstorm. The low value systems on 700 hPa and 850 hPa formed forward-tilting structure. The CAPE value over Zhengzhou station was 1717.8 J·kg-1, and the temperature difference between 850 hPa and 500 hPa exceeded 27 ℃, specific humidity on 850 hPa in most parts of Henan Province exceeded 14 g·kg-1. (3) The low vortex and shear line on 700 hPa, the shear line on 850 hPa and the weak cold air near surface layer were the meso-α scale systems triggering the convective storm firstly. The outflow boundary, surface convergence line and meso-β scale low were the meso-β scale systems triggering the rainstorm．(4) When outflow boundary moved far away from the thunderstorm quickly, it was hard to trigger new convection. But when it met another outflow boundary or a surface convergence line, or a meso-β scale low pressure, it could result in a new thunderstorm. (5) The newborn cells of backward propagation in multi-cell storms moved downstream under the action of steering flow and resulted in train effect and torrential rain. (6) Finally, the concept model of this convective rainstorm was built based on the above research, it can offer a reference for the operational forecast of convective rainstorms.

Key words: convective rainstorm, meso-β-scale low pressure, train effect, concept model