Comparison of Snowfall Rate from Gauge, Ground Radar, Space Radar, and Space Radiometer over the Contiguous United States

This study compares the hourly snowfall rate from ground gauges operated by National Weather Service, Global Precipitation Measurement Mission (GPM) dual-frequency precipitation radar (DPR), GPM microwave imager (GMI), and Multiple Radar Multiple Sensors (MRMS) ground radar during the 2014-2015 cold season. The gauge observations are taken as a reference for the DPR, GMI, and MRMS observations. It is found that snowfall rates from DPR, GMI, and MRMS agree better with gauge observations over the eastern half (East of 100°W) of the Contiguous United States (CONUS) in comparison to the western half, as indicated by the larger correlation values, smaller root-mean-square errors, and lower biases for the eastern region. The larger discrepancy over the western CONUS is most likely caused by the severe terrain blockage in that region. Among the DPR, GMI, and MRMS, the DPR has the best performance for both snowfall detection and intensity due to the higher frequency Ka-band radar (35 GHz). In terms of the snowfall detection, it is demonstrated that the MRMS ground radar has far less accuracy detecting snowfall events over the Rocky Mountain regions when compared to DPR and GMI, which can detect most of the snow events over that region. In the eastern CONUS, the MRMS agrees better with ground gauge observations, compared with that from GMI.