Enhancing Satellite Validation in Antarctica: A Novel K2W Methodology for Comparing Ground-Based Measurements at K-band with Spaceborne Radar Observations Collected at W band

Validating satellite measurements and geophysical retrievals is crucial for Earth observation missions, particularly in remote regions like Antarctica. This task faces challenges due to the harsh environment, logistical complexities, equipment maintenance, and operational costs. In Antarctica, where satellite observations play a pivotal role in estimating precipitation, validating satellite products through ground-based measurements is imperative but limited.

Cloud Profiling Radar (CPR) on NASA's CloudSat satellite provides reflectivity profiles at W-band (94 GHz), while the upcoming ESA/JAXA EarthCARE satellite will offer Doppler profiles in addition to reflectivity profiles. Despite efforts to enhance instrumentation for ice particle profiling at some Antarctic research stations, widely-used instruments include the Micro Rain Radar (MRR) and laser disdrometers.

This work introduces a novel validation methodology, K2W, which combines ground-based reflectivity profiles at K-band (24 GHz) from MRR and laser disdrometer observations. K2W enables the simulation of reflectivity and Doppler profiles at W-band, facilitating the validation of satellite-borne radar measurements at 94 GHz.

A comparison between CloudSat reflectivity profiles and K2W profiles during a satellite overpass at the Italian Antarctic station “Mario Zucchelli” revealed a mean difference of 0.2 dB at the lowest satellite radar range bin, with a time lag within ±12.5 min and distance within 25 km around the CloudSat overpass. Additionally, K2W simulated the 94 GHz Doppler velocity below 1 km altitude expected by EarthCARE, yielding a standard deviation of the simulated Doppler velocity less than 0.2 m s^-1.

The use of simulated K2W profiles significantly enhances precipitation quantification over Antarctica and validates satellite measurements with reduced attenuation compared to ground-based W-band radar. K2W, utilizing MRR and disdrometer available at most Antarctic stations, broadens the scope for validation sites. The proposed methodology extends its applicability to assessing EarthCARE CPR Doppler velocity products and Level 2 standard precipitation products at various ground observation sites.