Cool Skin Effect as Seen from a New Generation Geostationary Satellite Himawari-8

The cool skin effect refers to the phenomenon where the surface skin temperature of the ocean is always slightly cooler than the temperature of the water directly underneath due to the ubiquitous cooling processes at the ocean surface, especially in the absence of solar radiation. The cool skin effect plays a critical role in the estimation of heat, momentum, and gas exchange between the air and the sea. However, the scarcity of observational data greatly hinders the accurate assessment of the cool skin effect. Here, the matchup data from the new generation geostationary satellite Himawari-8 and in situ sea surface temperature (SST) observations are used to evaluate the performance and dependence on the cool skin effect in the low/mid-latitude oceans. Results show that the intensity of the cool skin effect as revealed by Himawari-8 (-0.16 K) is found to be relatively weaker than previously published cool skin models based on in situ concurrent observations. A considerable amount of warm skin signals has been detected in the high-latitude oceans (e.g., Southern Ocean) under the circumstances of positive air-sea temperature difference and high wind, which may be the main cause of discrepancies with previous thoughts on the cool skin effect.

Automated summary

The cool skin effect, where the ocean's surface skin temperature is slightly cooler than the water directly underneath, plays a critical role in heat, momentum, and gas exchange between the air and sea. This study used Himawari-8 satellite data and in situ sea surface temperature observations to evaluate the performance and dependence of the cool skin effect in low/mid-latitude oceans. The results showed a weaker cool skin effect than previously modeled, with warm skin signals detected in high-latitude oceans.