Assessment of Sea Surface Wind Measurements from Wave Gliders in Tropical Cyclones

Abstract

Reliable in situ observations of sea surface wind (SSW) in tropical cyclones (TCs) remain extremely limited because of the difficulty of operating conventional observing platforms under severe weather conditions. Autonomous, uncrewed surface vehicles (USVs), such as Wave Gliders (WGs), offer a promising solution, but their observational reliability under TC conditions has not been systematically assessed. This study presents a comprehensive evaluation of WG-derived SSW measurements in TCs using (1) internal quality assessment, (2) inter-sensor consistency analysis, and (3) comparisons with satellite observations (AMSR2, SMAP, ASCAT, and SAR) and a numerical weather prediction (NWP) model (JMA LFM). Before evaluating inter-sensor consistency, the influence of platform motion on the 10 m height conversion was assessed. The effect of platform motion correction was negligible, with a maximum RMSE of 0.11 m/s for wind speed and only minor changes in wind direction. Comparisons between sensors mounted on different USVs using 10 m-height-normalized winds showed good agreement over the wind-speed ranges sampled during the TC cases, with the most stable agreement observed under moderate-to-high wind conditions. Comparisons with external datasets also showed good consistency, although the statistical robustness varied among products because of differences in the number of available collocations. For samples within 500 km of the TC center, wind speed RMSE ranged from approximately 0.9 to 4.4 m/s among individual satellite products, while the integrated satellite comparison yielded an RMSE value of 2.36 m/s and the LFM comparison yielded an RMSE of 2.35 m/s. An integrated comparison using all available satellite products also showed strong agreement for wind speed, while the LFM exhibited variability comparable to that of the WG observations under TC-approach conditions. However, the number of independent collocations above 25 m/s was limited, precluding a robust assessment under extreme TC wind conditions. These results demonstrate that mid-size USVs can provide consistent and valuable in situ SSW observations over the range of TC conditions evaluated in this study and highlight their potential for evaluating satellite wind products, supporting NWP model improvement, and advancing air–sea interaction studies in extreme weather environments.