Abstract: Using hourly precipitation data from ground stations in Sichuan Province from September 2022 to August 2023,the accuracy of Quantitative Precipitation Estimation (QPE) products from FengYun-4A (FY-4A) and FengYun-4B (FY-4B) satellites in Sichuan was compared by statistical and evaluation indicators.The results show that FY-4A and FY-4B QPE products perform better in regions with less precipitation,such as the plateau region,than in regions with more precipitation,like northeastern Sichuan and the plateau-basin transition zone.FY-4A tends to underestimate precipitation,while FY-4B tends to overestimate it,with FY-4A performing better overall than FY-4B.At the annual scale,the correlation coefficients between precipitation from FY-4A and FY-4B and that observed on the ground are 0.69 and 0.59,respectively.This indicates that FY-4A is closer to ground-based precipitation observations.At the seasonal and monthly scales,the correlation coefficients between the two satellite QPE products and the ground-observed precipitation are high in spring and October,and lower in winter.FY-4A performs better in spring and September-October,while FY-4B performs better in July-August.Except for the slight overestimation by FY-4B for precipitation below 2.0 mm·h^-1,both QPE products mainly underestimate precipitation at other precipitation levels,with FY-4A underestimating more.As rainfall intensity increases,the underestimation worsens,and the root mean square error increases.FY-4A shows slightly better performance than FY-4B when there is no ground precipitation.Analysis of two heavy rainfall events in July 2023 indicates that both QPE products can indicate the approximate range of precipitation areas and reflect the timing of precipitation occurrence well,but both underestimate the amount of precipitation.

Key words: FY-4A, FY-4B, QPE (Quantitative Precipitation Estimation), FengYun Meteorological Satellite, Accuracy Assessment