How Spaceborne Radar can enhance ground radar network for improved understanding of precipitation rates and types over mountainous regions

Over complex terrains, ground radars usually rely on scans at higher elevation angles to observe precipitating systems. The radar estimation of precipitation rates and types might have considerable errors if vertical structure of precipitation is not considered because radar reflectivity varies with height due to evaporation at low levels as well as processes of melting, aggregation, and drop break-up. The vertical profile of reflectivity (VPR) links the surface precipitation to the radar observation at higher levels, which is very useful for understanding precipitation rates and types. However, in mountainous regions, radar measurements near the surface are less ubiquitous and the complete VPRs might not be fully obtained. The observational limitations of ground-based radar can be mitigated by spacebone radar whose measurements are much less impacted by mountain blockages and beam broadening effects in the vertical direction. Researchers at the University of Oklahoma have demonstrated the integration of the Tropical Rainfall Measurement Mission (TRMM) Precipitation Radar products (4-km precipitation quantity, types, and 250-meter vertical profile of reflectivity (VPR)) into the NEXRAD ground-based radar rainfall estimation system, so called the VPR-Identification and Enhancement (VPR-IE) approach. Performance of the VPR-IE is systematically evaluated by rain gauges measurements over the Mountainous West Region of the U.S.. The results indicate improvements in understanding of precipitation rates and types over mountainous regions following the incorporation of space-based radar information into ground radar networks.