Joint Cloud Water Path and Rain Water Path Retrievals from ORACLES Observations

This study presents a new algorithm that combines W-band reflectivity measurements from the Airborne Precipitation Radar - 3rd generation (APR-3), passive radiometric cloud optical depth and effective radius retrievals from the Research Scanning Polarimeter (RSP) to estimate total liquid water path in warm clouds and identify the contributions from cloud water path (CWP) and rainwater path (RWP). The resulting CWP estimates are primarily determined by the optical depth input, although reflectivity measurements contribute ~10-50% of the uncertainty due to attenuation through the profile. Uncertainties in CWP estimates across all conditions are 25% to 35%, while RWP uncertainty estimates frequently exceed 100%. Two thirds of all radar-detected clouds observed during the ObseRvations of Aerosols above CLouds and their intEractionS (ORACLES) campaign that took place from 2016-2018 over the southeast Atlantic Ocean have CWP between 41 and 168 g m-2 and almost all CWPs (99%) between 6 to 445 g m-2. RWP, by contrast, typically makes up a much smaller fraction of total liquid water path (LWP) with more than 70% of raining clouds having less than 10 g m-2 of rainwater. In heavier warm rain (i.e. rain rate exceeding 40 mm h-1 or 1000 mm d-1), however, RWP is observed to exceed 2500 g m-2. CWP (RWP) is