Global Diurnal Sea Surface Temperature Variability and the Role of Ocean‐Atmosphere Interactions

Diurnal changes in sea surface temperature (SST) play a crucial role in shaping weather, the water cycle, and climate dynamics. While diurnal SST variability has been studied previously, our work highlights diurnal cooling as a frequent and previously underrecognised phenomenon, accounting for over 38% of daily SST changes. Using a decade of satellite observations, we identify global patterns of daily SST variability, capturing three distinct states: diurnal warming, a balanced state, and diurnal cooling. These states reflect varying upper-ocean mixing regimes driven by atmospheric conditions, including wind, clouds, and precipitation. Calm, sunny days drive diurnal warming in the summer and transition seasons of tropical and mid-latitude regions, while diurnal cooling occurs primarily in high-latitude winters, highly modulated by the timing of passing storms.

Reference: Dror, T., Flores, J.M., & Koren, I. (2025). Global diurnal sea surface temperature variability and the role of ocean‐atmosphere interactions. J. Geophys. Res.: Oceans, 130(8), e2025JC022862.  https://doi.org/10.1029/2025JC022862