Performance Assessment of GPM IMERG Products at Different Time Resolutions, Climatic Areas and Topographic Conditions in Catalonia

Quantitative Precipitation Estimates (QPEs) from the Integrated Multisatellite Retrievals for GPM (IMERG) provide crucial information about spatio-temporal distribution of precipitation in semiarid regions with complex orography, such as Catalonia (NE Spain). The network automatic weather stations Meteorological Service is used to assess performance three IMERG products (Early, Late and Final) at different time scales, ranging yearly sub-daily periods. analysis a half-hourly scale also considered orographic features (valley, flat ridgetop), diverse climatic conditions (BSk, Csa, Cf Df) five categories related rainfall intensity (light, moderate, intense, very intense torrential). While IMERG_E IMERG_L overestimate precipitation, IMERG_F reduces error all temporal scales. However, calibration which Final run subjected causes underestimation regardless some areas, Pyrenees mountains. proportion false alarms problem IMERG, especially during summer, mainly associated detection form light rainfall. At showed high bias low correlation values, indicating remaining challenge satellite sensors estimate resolution. This behaviour was more evident areas cold semi-arid climates, wherein overestimates than 30% were found. In contrast, classified heavy torrential significant underestimates, higher 80%, reflecting inability detect extreme events.