Relationships between SSTs, air temperature, and coastal fog using field data and satellite remote sensing

Abstract

Understanding how sea surface temperature (SST), air temperature, and coastal fog interact is increasingly important for studying climate refugia in coastal environments, increasingly so as the climate warms and coastal zones are exposed to more extreme conditions during the summer. Using Landsat imagery, in situ air temperature and relative humidity (TRH) data, time-lapse camera imagery, and Conductivity Temperature Depth sensor (CTD) profiles, we studied spatial and temporal variability in these components of ocean-atmosphere interaction around San Juan Island, WA. SSTs derived from Landsat images from summer 2021-2024 showed consistent temperature differences between warmer water at the north end and colder water at the south end of the island. Air temperature differences between sites typically followed SST patterns, but correlations varied with local weather patterns. Time-lapse camera imagery and TRH data showed foggy days to be cooler and more humid than clear days. CTD casts showed strong short-term stratification during rising tides and indicated upwelling in certain regions, suggesting that mechanical mixing may influence SST variability. These results refine our understanding of how local ocean-atmosphere interactions can influence temperature and fog formation and can help identify coastal climate refugia.