多卫星融合降水产品对2015—2020年登陆浙江台风降水的监测能力评估

Evaluation of monitoring ability of the integrated multi-satellite retrievals for precipitation during typhoon landing in Zhejiang from 2015 to 2020

基于浙江省雨量站观测数据,利用相对偏差(RB)、均方根误差(RMSE)、相关系数(CC)对2015—2020年登陆浙江的“灿鸿”“摩羯”“利奇马”“米娜”和“黑格比”影响期间全球降水观测计划GPM多卫星融合产品V06B版的准实时降水产品IMERG_ER(简称IMERG)进行总体评估,并采用探测率(POD)、空报率(FAR)和临界成功指数(CSI)来评估不同降水量级下IMERG的降水估测能力。结果表明:IMERG总体能较好反映降水的空间分布特征,但对强降水落区范围大小的捕捉能力尚有一定不足。IMERG对“灿鸿”过程总降水量具有一定程度的低估,对“摩羯”“利奇马”“米娜”和“黑格比”过程总降水量存在高估。此外,IMERG对“黑格比”降水变化的捕捉能力最强,接着依次是“灿鸿”“摩羯”和“利奇马”,较差的是“米娜”。从分级检验结果看,随着降水量级的增加,POD和CSI稳中有降,FAR稳中有升,即IMERG对小雨的辨识能力最优,对大暴雨的捕捉能力较差,同时高估了较强降水发生的可能性。客观上看,IMERG对个别台风降水强度的捕捉能力稍显不足,定量误差较大,但总体上追踪台风降水动态变化的能力尚可,具有反映降水峰值和谷值数量及其变化的能力,同时对山区和平原地区降水的估测能力相当,山区有时优于平原地区,可尝试用该产品估测复杂地形下台风降水变化。

Based on the observational data of precipitation at the stations of Zhejiang,relative bias(RB),root mean square error(RMSE),and correlation coefficient(CC)were used to evaluate the quasi-real-time product IMERG_ER V06B of GPM satellite during the landing periods of typhoon Chan-hom,Yagi,Lekima,Mitag,and Hagupit during 2015 to 2020.POD,FARand CSIwere used to evaluate the ability of precipitation retrieval of IMERG at different precipitation levels.The results show that the IMERG precipitation data of GPM can reflect the spatial distribution characteristics of precipitation,but its ability to capture the range of heavy precipitation is still insufficient.Precipitation during typhoon Yagi,Lekima,Mitag,and Hagupit were overestimated,while precipitation during typhoon Chan-hom were underestimated.IMERG has the ability to capture the change of precipitation of typhoon Hagupit,followed by typhoon Chan-hom,Yagi,and Lekima,and typhoon Mitag is the worst.According to the results of classification test,PODand CSIdecrease,while FARincreases with the increase of precipitation,which indicates that IMERG has the best ability to identify light rain,but poor ability to capture heavy rain.Meanwhile,IMERG overestimated the possibility of heavy precipitation.Objectively,precipitation product of IMERG_ER V06B is insufficient to capture the precipitation intensity of typhoon,and the quantitative error of individual typhoon is large.Overall,it has a fair ability to capture the number and variation of peak and valley of typhoon rainfall,which can be applied to estimate the change of typhoon rainfall in complex terrain,due to its similar if not better ability of retrieving precipitation in mountainous area as in plain area.