2012年7月29日~30日宁夏中北部区域暴雨落区的动力诊断分析

Dynamic Analysis of a Heavy Rainstorm in North Central Area of Ningxia District from July 29 to 30, 2012

摘要: 利用NCEP逐日四次的FNL全球再分析格点资料，网格距1˚ × 1˚，通过分析垂直螺旋度和湿位涡，对发生在宁夏中北部地区的一次暴雨天气过程的暴雨落区进行动力诊断分析。结果表明：1) 垂直螺旋度能够体现暴雨的动力作用，低层正中心、高层副中心的相互作用，使低层辐合、高层辐散，高低层抽吸作用加强，有利于不稳定能量的释放。2) 湿位涡是能够体现动力、热力作用相结合的物理量，MPV1显示出暴雨时段的对流不稳定状态，MPV2则能表明斜压不稳定，为暴雨提供了必要的动力条件。通过对比分析发现，垂直螺旋度的大值区、MPV1负大值区、MPV2的正值区三者能够基本重合，与暴雨落区有较好的对应关系。

Abstract: NCEP 1˚ × 1˚ reanalysis data are used to conduct a diagnostic analysis of vertical helix and moist potential vorticity of a heavy rain weather process of Ningxia north-central area. The results showed that: 1) The vertical helicity can reflect the dynamic effect of heavy rain, and the interaction between the low-level positive center and the high-level sub-center enables low-level convergence, high-level divergence, and enhanced high-low layer suction, which is conducive to the release of unstable energy. 2) MPV is able to reflect the dynamic and thermal effects of combining physical, MPV1 shows convective instability storm period, and MPV2 is able to show that baroclinic instability, to provide the necessary impetus storm conditions. By comparison analysis, vertical helicity of large area, MPV1 negative large value area and MPV2 positive area can be substantially coincident with a good correspondence with the heavy rain area.