Evaluation of Effects on Dual-Frequency Precipitation Radar Observations Due to the Orbit Boost of the GPM Core Observatory

The NASA and the JAXA performed orbit boost maneuvers in November 2023 that raised the altitude of the Global Precipitation Measurement (GPM) Core Observatory from 407 km to 442 km to extend its lifetime. Effects of the orbit boost on the spaceborne precipitation radar have been investigated in the Tropical Rainfall Measuring Mission (TRMM). This study evaluates effects on Dual-frequency Precipitation Radar (DPR) observations due to the orbit boost. Spatial resolution at the nadir and swath width is changed at 5.04km×5.04km and 255.8 km at the satellite altitude of 407 km to 5.48km×5.48km and 277.9 km at the satellite altitude of 442 km, respectively. Observation data confirmed that changes in the sampling were larger in the cross-track direction (about 5 km to 5.5 km at the nadir). It was found that the DPR coverage tendency was changed by the GPM orbit boost. By analyzing measured radar reflectivity factor at storm top height over the ocean, the sensitivity degradation was found for about 0.8-0.9dB for KuPR, and about 0.7-0.9dB for KaPR.