为了更好的提高成都地区(30.1°N-31.5°N, 103°E-104.9°E)强降水的预报准确率, 利用国家气象中心(T639)高分辨预报场(0.28°×0.28°)资料以及加密自动站降水量资料对成都地区2011-2012年汛期(7-9月)共计15例强降水个例进行湿螺旋度指标的统计分析, 分别归纳总结出3 h、24 h内强降水发生、发展及落区分布的判据。利用这些判据对2013年6月20日以及7月8日发生在成都地区的两例强降水过程进行检验, 同时根据这些判据对成都2013年6-8月强降水过程进行检验评分并投入业务试应用。结果表明, 低层湿螺旋度对成都区域性暴雨的预报准确率较高。700 hPa和850 hPa湿螺旋度正值区的分布对强降水落区分布有较好的预报效果, 强降水出现在700 hPa湿螺旋度正、负值等值线密集区(靠近正值一侧), 以及850 hPa正值区; 当700 hPa连续5~8个3 h 维持在20×10^-11~80×10^-11 Pa·s^-3湿螺旋度时, 出现区域性暴雨天气; 当700 hPa连续5~8个3 h 维持在20×10^-11~140×10^-11 Pa·s^-3湿螺旋度时, 出现区域性大暴雨天气; 当不同层次上出现300×10^-11~500×10^-11 Pa·s^-3时, 可能出现局地强对流天气, 如大风、短时强降水等。

In order to better improve the heavy rain forecast accuracy in Chengdu area (30.1°-N31.5 °N, 103°E-104.9°E, samehere in after), based on T639 high resolution (0.28°×0.28°) data and the data of encrypted automatic stations of Chengdu, 15 cases of heavy rainfall indexes for moist helicity in flood season from July to September in 2011 and 2012 were analyzed by statistical method, included the moist helicity indexes of 3 hours, 24 hours strong precipitation occurrence, development and falling area distribution. Two cases of strong precipitation process in Chengdu Region were checked out and scored by using these criteria and threw into the business forecasting work in the flood season. The results showed that distribution of 700 hPa or 850 hPa moist helicity can give good indication to the distribution of rainfall. Heavy rainfall appeared in the positive and negative moist helicity value isoline concentration areas on 700 hPa and close to the positive side, but in the positive area on 850 hPa. When regional heavy rainfall occurs, moist helicity values reached the number of index values(20×10^-11~80×10^-11 Pa·s^-3) for 5~8 times or more in 3 hours interval forecasting field; When the moist helicity values reached the number of index values(20×10^-11~140×10^-11 Pa·s^-3) for 5~8 times or more in 3 hours interval forecasting field, regional torrential rainfall occurs; When moist helicity values for 300×10^-11~500×10^-11 Pa·s ^-3 appeared in different levels, local strong convective weather, such as wind, short-time strong rainfall would possible happen.