Thermal Recovery Dynamics of the Ocean’s Cool-Skin Layer After Complete Mixing

The air-sea heat exchange has a substantial impact on the heat budget of the surface ocean. Due to the heat loss across the air-sea interface, the uppermost millimeter of the ocean is generally cooler than the underlying water. This cool-skin layer can be naturally disrupted by processes such as wave breaking or wind stress, as well as by anthropogenic factors like ships or offshore wind turbines. Understanding recovery times after complete disturbance is hindered by observational challenges. Previous studies, which used stationary observations with thermal imagery, have focused on natural disruptions. This study presents in situ high-resolution temperature measurements of the skin and near-surface layer during the complete disturbance of the ocean’s surface layer using the autonomous surface vehicle Halobates. The vehicle drifted within artificially disturbed water masses, enabling observation and analysis of thermal recovery. The average temperature difference between skin and near-surface layer was –0.240 ± 0.037°C. The thickness of the skin layer was computed as 1.06 ± 0.16 mm approaching 0.2 mm during disturbances. Recovery times of the cool-skin layer ranged from 62 to 157 seconds, with rates between –0.047 and –0.140°C min^–1. The main findings demonstrate that the complete recovery of the cool-skin layer can take up to three minutes following intense surface disruption, such as that caused by vessel-induced turbulence. These results have important implications for modeling air-sea interactions in areas with frequent human activity. Combined with prior research on rapid recovery from natural disturbances, these results enhance our understanding of surface layer dynamics.