Evaluation and correction of GPM satellite precipitation products during Typhoon "In-Fa" affecting Zhejiang

To understand and improve the performance and quality of Global Precipitation Measurement (GPM) satellite-derived precipitation products during the typhoon process, with gauge observations from ground meteorological stations, this study used the successive and optimal interpolation correction methods to correct the GPM precipitation products. The performance of GPM products (Version 6) before and after the correction at different time scales are evaluated with the products during the two landfalls of Typhon"In-Fa". Results show that the original GPM precipitation products fail to describe the strong rainfall center over the high terrain area, which significantly underestimates the precipitation by approximately 45%. This is mainly due to the underestimation of the large values in the northeast region of Zhejiang province. The analysis of precipitation classification inspection suggests that the uncorrected GPM satellite-derived products have good capability for light rain, but poor for other rainfall levels. After the successive and optimal interpolation correction, significant improvement can be found in the cumulative, daily, and hourly rainfall products. The products with successive correction are better, while the product with optimal interpolation slightly overestimates the actual precipitation. The corrected GPM products can not only describe the heavy precipitation center related to the terrain but also reflect heavy rainstorms and heavy precipitation with hourly rainfall intensity greater than 23 mm·h^-1.