An Airborne G-Band Water Vapor Radiometer and Dropsonde Validation of Reanalysis and NWP Precipitable Water Vapor over the Korean Peninsula

Accurate representation of Precipitable Water Vapor (PWV) in numerical models is critical over the meteorologically complex Korean Peninsula, yet validation remains a challenge. This study presents a unique airborne validation of hourly PWV from two local Numerical Weather Prediction (NWP) models—the Local Data Assimilation and Prediction System (LDAPS) and the Korea Local Analysis and Prediction System (KLAPS)—and two global reanalysis datasets—the ECMWF Reanalysis v5 (ERA5) and the Modern-Era Retrospective Analysis for Research and Applications, Version 2 (MERRA-2). We utilize a G-band Water Vapor Radiometer (GVR) and dropsondes, applying a rigorous multi-stage quality control (QC) procedure to ensure data reliability. Two strategies were used: comparing GVR-measured upper-column PWV against model layers and comparing a total-column GVR–dropsonde composite against the models’ total PWV. Our key finding reveals that the ERA5 reanalysis consistently provides the most accurate representation of both upper-air and total column PWV. In contrast, the high-resolution local models exhibit significant dry biases, particularly in moist and cloudy conditions. These results underscore the value of airborne validation and suggest that for water vapor analysis over Korea, ERA5 serves as a more reliable benchmark than local models, highlighting the need to improve humidity assimilation and microphysics in regional systems.