2.3.3. IMERG

GPM is an international satellite mission. Its core observatory was launched by the National Aeronautics and Space Administration (NASA) and the Japanese Aerospace Exploration Agency (JAXA) on 27 February 2014. The first space-borne Ku/Ka-band Dual-frequency Precipitation Radar (DPR) was carried on the GPM Core Observatory, making it more sensitive to light rain rates and snowfall. IMERG is designed to intercalibrate, merge, and interpolate "all" data from satellites in the GPM constellation at fine temporal and special scales over the entire globe [11]. The version 06 IMERG Final run products were used in this study. The spatial resolution of IMERG is 0.1◦ × 0.1◦, which is the same as FY-2 QPE products. The temporal resolution is half an hour, and the hourly data used in this study was obtained by averaging the two datafiles in the same hour.

Considering the fact that FY-2 QPE datasets merge precipitation information from ground observations, we applied the IMERG Final run dataset (V06B), which is calibrated with ground station data with a latency of about 3.5 months, as another precipitation estimate product, in this study. IMERG data could be downloaded from the Precipitation Measurement Mission's (PMM) website (https://pmm.nasa.gov/data-access/downloads/gpm).
