精细化评估GPM/IMERG产品对台风“妮坦”降水的观测精度

采用地面加密雨量计观测资料,以1 h、3 h、6 h、12 h和24 h等多个时间尺度分别评估了全球降水观测GPM （Global Precipitation Measurement）计划降水产品IMERG （Integrated Multi-satellite Retrievals for GPM）对台风"妮妲"降水中小雨、中雨、大雨和暴雨等不同量级降水的估计能力,主要结论如下：（1）降水累积时长会影响IMERG降水产品的估计精度。随着降水累计时长的增加,IMERG与地面雨量计观测结果的一致性加大,相对偏差和偏差的随机性均减小;（2）降水累计时长1 h时,IMERG对不同量级降水的观测精度均存在较大偏差;（3） IMERG降水产品会高估小雨时地面雨量计的降水量,且低估小雨事件发生的概率,对于小雨等级降水的观测能力还有待提高;（4） IMERG能较好地观测到暴雨降水的空间分布区域,但对暴雨的估计量级会明显偏低。

Refined evaluation of the accuracy of GPM/IMERG in the precipitation process of typhoon Nida

The precipitation estimation ability of the integrated multi-satellite retrievals for global precipitation measurement (GPM/IMERG) was refined evaluated in the study, using the measurements from the dense ground-based gauges for Typhoon Nida precipitation, in multiple temporal scales including 1, 3, 6, 12 and 24 hour precipitation accumulation time for different rain intensity, such as the light rain, the moderate rain, the heavy rain and the rainstorm, respectively. The main conclusions are as follows:(1) The duration of precipitation accumulation affects the estimation accuracy of IMERG. The consistency between IMERG and the ground-based gauges increases as the increase of precipitation accumulation time, and the relative bias and random error of relative bias both decrease. (2) The accuracy of IMERG with different rain intensity has a large deviation from the ground-based gauges in 1 hour precipitation accumulation. (3) The IMERG overestimate the precipitation and underestimate the probability of light rain. The accuracy of IMERG for light rain needs to be improved. (4) The IMERG can capture the spatial distribution of rainstorm. However, the IMERG has a certain degree of underestimation when the rain intensity is large.