A revised ocean mixed layer model for better simulating the diurnal variation of ocean skin temperature

Abstract. Sea surface temperature (SST) is a pivotal parameter in climate, weather, and ocean sciences because it plays a decisive role in ocean-atmosphere interactions. Identifying deficiencies in the ERA5 reanalysis of ocean skin temperature, we revisited the ocean mixed layer (OML) model used at ECMWF and identified errors in the model, and revised it accordingly. Validation of the revised model was conducted through comparisons of simulated temperatures at the skin layer and 1-m depth with observations from ship-board infrared interferometers and buoy-mounted thermistors. These comparisons revealed a strong correlation, with an absolute mean deviation of less than 0.1 K and a standard deviation under 0.5 K. We concluded that the temperature at the ocean-atmosphere interface possesses the same degree of accuracy. Moreover, the results closely align with anticipated distributions of solar radiation. Consequently, the revised OML model shows promising potential for improving the simulation of diurnal interface SST variations in weather and climate models.