Validation of Spaceborne Precipitation Radar Data by Rain Gauges and Disdrometers over the Complex Topography of the Northeastern Indian Subcontinent

Abstract

Near-surface rain rate datasets derived from the Tropical Rainfall Measuring Mission Precipitation Radar (TRMM PR) and Global Precipitation Measurement Dual-frequency Precipitation Radar (GPM DPR) and near-surface raindrop size distribution (DSD) parameters derived from the GPM DPR were validated using 43 tipping-bucket rain gauges installed over the northeastern Indian subcontinent and two Parsivel² disdrometers installed on the Meghalaya Plateau, India. Both TRMM PR version 7 and version 8 products significantly underestimated the rainfall over the Indian subcontinent during the monsoon season (June–September). The GPM DPR version 06A product also significantly underestimated the rainfall at stations on the Meghalaya Plateau, India. The heavy rainfall area (HRA) of the Meghalaya Plateau in the TRMM PR climatology showed lighter rainfall on the plateau, whereas heavier rainfall was detected in adjacent valleys. Intense surface rainfall over the HRA may be detectable, because such intense rainfalls tended to occur from deeper convections, which were less affected by the ground clutter interferences. A comparison of the statistical features of the DSD parameters between the disdrometers and GPM DPR retrievals around the Meghalaya Plateau confirmed that an adequate assumption of the adjustment factor ϵ is important for improving the DSD parameters in GPM DPR retrievals.