Understanding Warm Rain Retrieval Uncertainties in Preparation for the Atmosphere Observing System

[14-Dec-2022]
Abstract: Satellite-based precipitation products show large differences in oceanic rain rates over regions where warm rain processes are dominant. NASA's planned Atmosphere Observing System (AOS) will include a dual-frequency radar with observations at Ka- and W-band. We test whether this satellite architecture, which combines sensitivity to cloud droplets and drizzle with sensitivity to larger raindrops, has the potential to reduce uncertainties in warm rain estimates. Using synthetic satellite measurements based on OceanRAIN disdrometer observations and output from a high-resolution cloud resolving model, we quantify retrieval uncertainties related to drop size distribution assumptions, nonuniform beam filling, surface clutter, and vertical variability. Combining all sources of uncertainty, the AOS satellite is found to significantly outperform the Global Precipitation Measurement (GPM) Core Observatory and CloudSat. To further demonstrate the utility of combining these two radar frequencies, we perform retrievals on near-coincident observations of warm rain from GPM and CloudSat.