IMERG系列产品在大汶河流域的降水监测能力评价

Evaluation of precipitation monitoring capability of IMERG series products in Dawen River basin

为探究高分辨率多卫星联合反演IMERG(Integrated Multi-satellitE Retrievals for GPM)卫星降水产品在大汶河流域的监测精度与适用性,以2001~2019年较长系列地面雨量站实测数据为基准,采用探测率、虚报率等11个指标,对IMERG系列Early、Late、Final产品在研究区的降水监测能力进行评价。结果表明:(1)日、月、年尺度下,Final产品的精度最好,Early、Late两个产品的精度基本一致,在时间上,IMERG系列产品均能较好反映流域降水的年际变化与年内分配;在空间上,表现为整体高估研究区降水量,低估泰山区域降水量(相对偏差小于-20%)。(2)在不同强度日降水探测能力方面,IMERG系列产品间差异不大,仅对小雨有较好的命中率(探测率>0.6)。各产品探测能力一般,整体表现为误报率较高(误报率>0.7)、探测率与关键成功率较低,同时,随着降水强度的增大,各产品探测能力呈下降趋势。(3) IMERG系列产品均具有一定的极端降水监测能力,Final产品评价结果更优、表现更为稳定,在参与评价的5个指数中,Final产品有4个指数结果最优,Late产品有1个最优,Early产品则有4个指数结果优于Late产品。总体上,IMERG系列数据均能较好反映大汶河流域(除泰山区域)降水的时空分布与极端降水情况,Final产品整体精度最高,Early、Late产品精度较为接近,其中,Early产品在极端降水监测中的表现好于Late产品,而对不同强度日降水事件的监测能力差于Late产品。

In order to explore the monitoring accuracy and applicability of high-resolution multi-satellite joint inversion IMERG(Integrated Multi-satellite Retrievals for GPM)satellite precipitation products in the Dawen River basin,based on a relatively long series of measured data of ground rainfall stations from 2001 to 2019,this paper used 11 indicators such as detection rate and false alarm rate to evaluate the precipitation monitoring capabilities of Early,Late and Final products of IMERG series in the study area.The results show that:①At the daily,monthly and annual scales,the accuracy of Final products is the best,and the accuracy of Early and Late products is basically same.In terms of time,the IMERG series products can better reflect the inter-annual variation and intra-annual distribution of precipitation in the basin.In terms of space,the precipitation in the study area was overestimated and the precipitation in the Taishan mountain area was underestimated(relative deviation less than-20%).②In view of the ability to detect daily precipitation of different intensities,the IMERG series products have minor differences and only have a good hit rate for light rain(detection rate>0.6).The detection ability of each product is general,and the overall performance is a high false alarm rate(false alarm rate>0.7),low detection rate and key success rate.At the same time,with the increase of precipitation intensity,the detection ability of each product shows a downward trend.③The IMERG series products have certain extreme precipitation monitoring capabilities.The Final product has better evaluation results and more stable performance.Because among the five indexes participating in the evaluation,the Final product has four index gaining optimal results,the Late product has one optimal,and the Early product has four index that are better than the Late product.In general,the IMERG series data can better reflect the spatial and temporal distribution of precipitation and extreme precipitation in the Dawen River basin(except Taishan mountain area).The overall accuracy of the Final product is the highest,and the accuracies of the Early and the Late products are relatively close.Among them,the performance of the Early products for extreme precipitation monitoring is better than that of the Late product,while the monitoring ability of daily precipitation events with different intensities is worse than that of the Late product.