Satellite Precipitation Estimates of Heavy Rainfall Events at Daily and Sub-daily Scales Compared with a Dense Rain Gauge Network

Satellite precipitation estimates such as the Integrated Multisatellite Estimates for GPM (IMERG) products provide valuable information over areas not covered by ground-based weather radars or rain gauge networks. Past research has confirmed their ability to reproduce global spatial features of precipitation fields at yearly and seasonal scales. However, spaceborne precipitation estimates at shorter time scales, particularly in case of heavy rainfall events, pose more challenges, with a general tendency to underestimation.

Based on a previous study comparing six years of IMERG products at different time scales with a dense rain gauge network over Catalonia, in NE Spain (Peino et al 2022, https://doi.org/10.3390/rs14205085), this presentation is focused on heavy rainfall events at daily and sub-daily scales. The area covered is classified according to different climate subdomains and terrain characteristics (flat, valley and ridgetop).

An analysis using both continuous variables (RMSE, ME, MAE) and contingency table scores (POD, FAR, HSS) is applied to events from 30 min to 24 h time scales considering different intensity thresholds and IMERG product contributions such as infrared (IR) or passive microwave (PMW) data. Preliminary results indicate the importance of the contribution of PMW sensors as higher errors are mostly found when PMW data is missing. Another important factor detected is the role of time lags found between IMERG products and surface observations which might be associated with IMERG processing assumptions on cloud movements. Selected case studies will illustrate these features, including comparison with additional ground-based precipitation observations during previous field campaigns such as ATMOUNT or LIAISE. This research was supported by projects WISE-PreP (RTI2018-098693-B-C32) and ARTEMIS (PID2021-124253OB-I00) and the Water Research Institute (IdRA) of the University of Barcelona.