基于FY-4A卫星数据的短时强降水监测预警指标

Monitoring and Early Warning Indicators of Short-Term Rainstorm Processes Based on FY-4A Satellite Data

选取2018—2021年汛期短时强降水天气过程,利用相关性分析、箱线图法和极值统计法,尝试研究FY-4A卫星产品在短时强降水天气过程中的监测预警指标。研究表明:(1)FY-4A卫星多通道数据可以作为短时强降水监测预警的定量化指标予以应用。(2)筛选出相关性较好的13项产品统计出短时强降水的监测预警指标,其中赋值类指标4项,数值判别类指标9项(含辅助指标3项);初步设定13项指标中有9项达标时,短时强降水会发生。(3)在评估基础上完善了指标,监测预警效果有所提高,TS评分提高5.4%,空报率降低2.7%,漏报率降低1.9%。

The short-time rainstorm caused by small and mesoscale weather systems,which has characteristics such as short duration and strong disaster potential.The short-time rainstorms are always the focus of meteorological research and the challenge in weather forecasting.Currently,FY-4A satellite products have a few applications in research and service,especially in the analysis of short-term rainstorms.The application and analysis of satellite cloud images in weather reports are still mainly based on judgment and qualitative extrapolation,lacking quantitative proximity prediction indicators of short-term rainstorms.Based on FY-4A satellite product data and ground precipitation observation data from 2018 to 2021,we study the analysis of short-term rainstorm weather processes in the flood season,which occurs from May to September in Ningxia.By using correlation analysis,box-plot and extreme value statistics methods,we evaluate the monitoring and early warning indicators of FY-4A satellite products in the weather process of short-term rainstorms.The results show that:(1)FY-4A satellite data can serve as not only qualitative indicators but also quantitative indicators for short-term rainstorms monitoring and early warning after processing with methods such as correlation analysis,box plot,and extreme value statistics.(2)Thirteen products of the FY-4A satellite have a good correlation with the sample sequence of short-term heavy precipitation,including Black Body Temperature(TBB),Convective Inception(CIX),Cloud Mask(CLM),Cloud Phase(CLP),Cloud Type(CLT),Cloud Top Height(CTH),Cloud Top Pressure(CTP),Cloud Top Temperature(CTT),Total Precipitable Water(TPW),Quantitative Rainfall Rate Estimation(QPE),Cloud Effective Radius(CER),Cloud Liquid Water Path(LWP)and Tropopause Folding Uppermost Height(TZD),which can serve as monitoring and early warning indicators.We set the criteria that short-term heavy rainfall will occur when nine out of thirteen product indicators meet the standards,which can be optimized and adjusted through operational practices.(3)Among the thirteen products,there are four key indicators,which are Convective Inception(CIX),Cloud Mask(CLM),Cloud Phase(CLP),and Cloud Type(CLT),and three auxiliary indicators,which are Cloud Top Height(CTH),Cloud Effective Radius(CER),and Cloud Liquid Water Path(LWP),while the other products are numerical discriminant indicators.(4)After improvement based on the evaluation,the True Skill Statistic(TS)increases by 5.4%,the false reporting rate decreases by 2.7%,and the miss reporting rate decreases by 1.9%.The study of monitoring and early warning indicators using FY-4A satellite multi-channel product data is an experimental trial and has great application value,especially in the application of quantitative indicators to intelligent discrimination and automatic alarm.This study holds significant importance for improving the early warning recognition and advance warning capabilities of short-term heavy precipitation.