AbstractOur understanding of temperature dissipation rate χ within the upper ocean boundary layer, which is critical for climate forecasts, is very limited. Near‐surface turbulence also affects dispersion of contaminants and biogeochemical tracers. Using high‐resolution optical turbulence measurements, scaling laws for χ are investigated under forcing states where either the daytime heat flux or the wind stress forcing is dominant. We find that χ remains constant over 1.5 times the significant wave height, while over a layer below, χ decays based on the local surface forcing. When the heat flux is dominant, traditional scaling based on the Monin‐Obukhov similarity theory remains valid; χ ∝ z−1. When the wind stress dominates, we observe the emergence of a new scaling, χ ∝ z−1/2, which is explained by invoking the effect of small‐scale coherent structures on vertical heat transport. These results have implications for improved modeling of the ocean's heat and CO2 intake.
