Characterization and Classification of Precipitation Using the NASA D3R Observations during GPM OLYMPEx Field Campaign

Dual-polarization weather radars have been widely used for rainfall measurement applications and studies of the microphysical characteristics of precipitation. Ground-based, dual-polarization radar systems are an important tool for the validation of satellite-based radar algorithms and products. The NASA dual-frequency, dual-polarization, Doppler radar (D3R), a ground validation (GV) radar for the Global Precipitation Measurement (GPM) mission, was deployed and operated between November 8th, 2015 and January 15th, 2016 as part of the Olympic Mountains Experiment (OLYMPEx). The primary goal of OLYMPEx is to validate rain and snow measurements in mid-latitude frontal systems moving from ocean to coast to mountains. This experiment provided a comprehensive set of multi-instrument observations to study how remotely sensed measurements of precipitation by GPM can be applied to a range of hydrologic, weather forecasting, and climate applications. The D3R’s observations were coordinated with a diverse array of instruments including the NASA NPOL S-band radar, the Ku/Ka-band HIWRAP on the ER2, and the APR3 Ku/Ka/W-band radar flying on the NASA DC8. The high-resolution Ku- and Ka-band observations from D3R can provide more detailed insight into the microphysical structure of precipitation for the ocean to land transition.

This paper presents an overview of the deployment and observations of the D3R during the OLYMPEx field campaign. A precipitation classification methodology implemented for the D3R’s Ku-band observations is outlined, and sample hydrometeor classification products are discussed. The D3R’s observations are compared with other instruments from the OLYMPEx field campaign to investigate the microphysical properties of precipitation in its domain. In addition, a statistical analysis and quantitative evaluation of the hydrometeor classification methodology is presented using in-situ airborne measurements.