Location: Hydrology and Remote Sensing LaboratoryTitle: Evaluation of IMERG V04A precipitation estimates over different topographic and climatic watersheds in China
|WEI, W. - Hohai University|
|LU, H. - Hohai University|
|ZHU, Y - Hohai University|
|SU, J. - Hohai University|
|WANG, J. - Hohai University|
Submitted to: Remote Sensing
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/1/2018
Publication Date: 12/28/2018
Citation: Wei, W., Lu, H., Crow, W.T., Zhu, Y., Su, J., Wang, J. 2018. Evaluation of IMERG V04A precipitation estimates over different topographic and climatic watersheds in China. Remote Sensing. 10:30. https://doi.org/10.3390/rs10010030.
Interpretive Summary: Remotely-sensed estimates of rainfall accumulation are valuable for agricultural drought monitoring and water resource assessment within regions of the world lacking adequate ground rain gauge coverage. However, before these estimates can be used with confidence, they must first be objectively evaluated for a wide range of land cover and climate conditions. This manuscript describes the evaluation of four different state-of-the-art satellite-based rainfall accumulation products over three separate basins in China. These comparisons yielded valuable insight regarding the relative performance of each project and identified specific instances in which the performance of a particular product was unacceptably poor. Results from this paper will be used to improve future versions of these rainfall products and help users select the best product for their specific application.
Technical Abstract: The algorithm for the Integrated Multi-satellitE Retrievals for the Global Precipitation Measurement (IMERG) was upgraded to Version 04 on 21 March 2017. Here, this new IMERG version, hereinafter referred to as “IMERG V04A”, is systematically evaluated over three watersheds in China for the period June 2014 to November 2015 using gauge measurements at multiple spatiotemporal scales. Concurrently, IMERG V04A is compared with precipitation products obtained from other satellite-based products (i.e., IMERG V03D, CMORPH (the Climate Prediction Center Morphing technique)-CRT and TRMM (the Tropical Rainfall Measuring Mission) 3B42). Results show that (1) the IMERG V04A generally performs better at the semi-humid Huaihe River Basin and the arid/semi-arid Weihe River Basin than in the Tibetan Plateau cold region. In addition, IMERG V04A demonstrates its worst performance during wintertime. (2) Over the Tibetan Plateau cold region, compared with other products, IMERG V04A underestimates precipitation with the largest negative relative bias (RB; -46.98%) and highest relative root-mean square error (57.65%) during the study period. Similar results are seen at the seasonal scale. Among all products, IMERG V03D demonstrates the best performance over the Tibetan Plateau. (3) Within the semi-humid Huaihe River Basin, IMERG V04A has a slight advantage over the other three satellite-based precipitation products with the lowest RMSE (0.32 mm/day) during the evaluation period. (4) Over the arid/semi-arid Weihe River Basin, in comparison with the other three products, TRMM 3B42 demonstrates the best performance according to statistical metrics. (5) In winter, IMERG V04A and IMERG V03D tend to underestimate the total precipitation with negative RBs (-70.62% vs. -6.47% over the Tibetan Plateau, -46.92% vs. -0.66% over the Weihe River Basin, respectively). These findings provide valuable feedback for both IMERG algorithm developers and data users.