Validation of the Final Monthly Integrated Multisatellite Retrievals for GPM (IMERG) Version 05 and Version 06 with Ground-Based Precipitation Gauge Measurements across the Canadian Arctic

Abstract

Abstract To assess the performance of the most recent versions of the Global Precipitation Measurement (GPM) Integrated Multisatellite Retrievals for GPM (IMERG), namely, V05 and V06, in Arctic regions, comparisons with Environment and Climate Change Canada (ECCC) Climate Network stations north of 60°N were performed. This study focuses on the IMERG monthly final products. The mean bias and mean error-weighted bias were assessed in comparison with 25 precipitation gauge measurements at ECCC Climate Network stations. The results of this study indicate that IMERG generally detects higher precipitation rates in the Canadian Arctic than ground-based gauge instruments, with differences ranging up to 0.05 and 0.04 mm h−1 for the mean bias and the mean error-weighted bias, respectively. Both IMERG versions perform similarly, except for a few stations, where V06 tends to agree slightly better with ground-based measurements. IMERG’s tendency to detect more precipitation is in good agreement with findings indicating that weighing gauge measurements suffer from wind undercatch and other impairing factors, leading to lower precipitation estimates. Biases between IMERG and ground-based stations were found to be slightly larger during summer and fall, which is likely related to the increased precipitation rates during these seasons. Correlations of both versions of IMERG with the ground-based measurements are considerably lower in winter and spring than during summer and fall, which might be linked to issues that passive microwave (PMW) sensors encounter over ice and snow. However, high correlation coefficients with medians of 0.75–0.8 during summer and fall are very encouraging for potential future applications.