Analysis of NASA GPM Ground Validation Multi-Frequency Radar Observations

Extending from the nearly two decade record of TRMM and the ever growing body of work its observations support, the joint NASA-JAXA Global Precipitation Measurement (GPM) mission has led a series of multi-organization ground validation (GV) field efforts. These GPM GV field campaigns, conducted over the last decade during GPM Core Observatory pre- and post-launch periods, have provided a trove of precipitation observations in an assortment of meteorological regimes and regions. As an enhancement to ground-based perspectives for validating GPM’s Dual-frequency Precipitation Radar (DPR), NASA’s Dual-frequency, Dual-polarization, Doppler (D3R) radar was designed to operate at the same frequencies as the DPR (Ku-/Ka-band). Both the D3R and NASA’s S-band, dual-polarimetric, Doppler radar (NPOL) were deployed concurrently among the array of sensors utilized for many of the GV field campaigns.

Previous work has demonstrated that the dual-frequency ratio (DFR) using Ku- and Ka-band (as well as other frequency combinations) can aid in identifying and partitioning liquid, solid, and mix-phase precipitation. Here, we discuss S-Ku-Ka-band multi-frequency analyses relying on NPOL and D3R observations. The larger frequency-gap of S- to Ka-band, and resulting Rayleigh/Mie scattering impacts, can provide additional microphysical distinctions. By combining the S-band NPOL data with D3R Ku-/Ka-band observations in space and time, we create multiple DFR multi-wavelength analyses. Particular attention is given to orographically enhanced events over the Pacific Ocean and Olympic Mountains during the OLYMPEX campaign. Hydrometeor types, derived using polarimetric information available from NPOL, enable the consideration of delineations referenced to bulk target phase and habit-type. Implications of our results, and prospects for a longer-term extension of the analysis, will be discussed.