Evaluation of the GPM IMERG precipitation estimates over complex terrain in the United States

Natural hazards due to weather extremes represent a significant threat to people and property in mountainous regions. In situ data to characterize precipitation are usually scarce in complex terrain and the impact of extreme precipitation events is often less known and anticipated than in other areas. Moreover, precipitation over complex terrain is often highly variable even over very small scales so reliable precipitation estimates remain a challenge. Satellite remote sensing can provide improved spatial coverage of precipitation estimates, yet their accuracy depends strongly on the complex interaction between weather and topography so the estimates are generally characterized by significant biases compared to ground measurements. We evaluate the Integrated Multi-Satellite Retrievals for Global Precipitation Measurement (GPM IMERG) precipitation product over mountain regions in the continental United States through comparison with an operational QPE dataset from the Multi-Radar Multi-Sensor (MRMS). The high space (1 km) and time (2 min) resolution of MRMS allows to investigate the GPM IMERG precipitation estimates across different spatial and temporal scales. The results show the ability of GPM IMERG with respect to estimating precipitation rates and detecting precipitation extremes in mountainous regions.