相似环流背景下降水量级差异甚大的2次过程对比分析

Comparative Analysis of Two Processes with Significant Differences in Precipitations Occurred in a Similar Circulation Background

为研究夏季暴雨空、漏报问题,利用常规气象观测资料、FY-2D气象卫星、雷达、自动气象站加密及NECP再分析等资料,对相似环流背景下2012年7月降水量级差异甚大的2次过程进行对比分析,结果表明:在大尺度相似环流背景下,上下游系统配置及有无中尺度系统生成是2次降水量级差异的主要原因。7月6日短波槽在东移过程中冷空气减弱,同时降水的动力、水汽以及不稳定条件变差,山西中南部出现小阵雨;7月8日冷空气东移加强,高度场与风场呈现非地转特征,中尺度切变线、中尺度急流、中尺度涡旋生成,影响降水的水汽输送及水汽辐合加强,山西中南部对流发展,出现区域性暴雨天气。因此,在相似环流背景条件下,通过分析上下游系统动态演变、物理量场高低空配置,对数值天气预报产品进行订正,以减少暴雨空、漏报。

In order to figure out the problem of summer rainstorm false forecast, we used the data from conventional meteorological observation, FY-2D meteorological satellite, radar, automatic weather stations and NECP reanalysis, to analyze two processes with great differences in precipitations in a similar circulation background in July, 2012. The results showed that the main reasons of great differences in two precipitations were the system configuration of upstream and downstream and generation of meso-scale system under the background of similar large scale circulation. On July 6, the cold air weakened while the short wave trough moving eastward, at the same time the dynamic conditions of precipitation, water vapor and instability conditions weakened, shower appeared in south central Shanxi. On July 8, the cold air strengthened while moving eastward, the height and wind fields showed apparent ageostrophic characteristics. Meso-scale shear line, jet stream and vortex were generated, the water vapor transport and convergence that influencing the precipitation strengthened, the convection developed, which leaded the emergence of regional rainstorm weather in south central Shanxi. Therefore, in a similar circulation background, the numerical weather forecasting products should be revised by analyzing the evolution of the upstream and downstream system, and the upper and lower configuration of the meteorological elements fields to reduce rainstorm false forecast.