雷州半岛一次典型局地暴雨成因分析

CAUSE ANALYSIS OF A TYPICAL LOCAL RAINSTORM OVER LEIZHOU PANINSULA

关键词:  雷州半岛  局地暴雨  敏感性分析

Key words:  Leizhou Peninsula  local rainstorm  sensitivity analysis

摘要:

利用ERA5再分析资料和实况资料，对发生在广东湛江的雷州半岛的一次典型局地暴雨进行对比分析和敏感性试验研究。结果表明：此次局地暴雨是由雷暴单体所造成，ERA5资料作为初始场能较好地模拟出高分辨率局地暴雨的生消过程、降水中心和主要降水时段。通过敏感性试验进一步研究发现，雷州半岛局地暴雨的关键是大气中水汽含量。减少雷州半岛土壤湿度，导致显热通量增大，潜热通量减少，增加雷州半岛土壤湿度，导致潜热通量增大，显热通量减少，但潜热通量和显热通量之和与参照试验基本相同，局地暴雨依然触发，土壤湿度不能决定局地暴雨触发与否，仅通过显热通量的大小提前或滞后触发局地暴雨。雷州半岛三面环海的海陆分布，下垫面非均匀加热，陆地相当于热源，对雷州半岛局地暴雨触发有决定性作用。

Abstract:

In the present research, a comparative analysis of and a sensitivity test study on a typical local rainstorm in Leizhou Peninsula were conducted using the ERA5 reanalysis data and real data. The results show that the local rainstorm was caused by a thunderstorm cell. The ERA5 data as the data of the initial field can better simulate with high resolution the local rainstorm process, precipitation center, and main precipitation period. The sensitivity test reveals that the key of the local rainstorm over Leizhou Peninsula is the water vapor in the atmosphere. Reduced soil moisture leads to an increase in sensible heat flux and a decrease in latent heat flux. Increased soil moisture leads to an increase in latent heat flux and a decrease in sensible heat flux, but the sum of latent heat flux and sensible heat flux basically remain the same as those in the reference experiment. The local rainstorm is still triggered, so the soil moisture cannot determine whether the local rainstorm is triggered or not. It is only triggered by the magnitude of the sensible heat flux in advance or behind the local rainstorm. Leizhou Peninsula is surrounded by the sea on three sides and the underlying surface is not uniformly heated, so the land serves as a heat source. Together, these factors play a decisive role in triggering the local rainstorm over Leizhou Peninsula.