EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Global ocean surface stratifications due to rain based on ERA5

Hugo Bellenger1, Xavier Perrot1, Lionel Guez1, Jean-Philippe Duvel1, Alexandre Supply2, Jacqueline Boutin2, and Gilles Reverdin2
Hugo Bellenger et al.
  • 1CNRS, LMD, Paris, France (
  • 2CNRS, LOCEAN, Paris, France

Temperature and Salinity at the ocean interface can be substantially different than their bulk values in the ocean mixed layer at 5-10 meters depth. The main phenomena that account for these differences are (i) the interfacial millimeter scale diffusive microlayer usually cooler and saltier than below due to surface fluxes and (ii) diurnal warm layers of few tens of centimeters to few meters that form under weak wind condition due to solar absorption. Although characterized by small vertical scales, these tightly wind-related phenomena corresponds to coherent structures up to the large-scale where they can impact air-sea exchanges of heat, water and chemical species. Another phenomenon that can impact global air-sea exchanges is the freshwater lenses produced by rain. Rain freshens and cools the ocean surface, as raindrops temperature is usually lower than surface temperature. The induced negative salinity anomaly enables surface cold anomalies to be sustained and further cooled down by surface fluxes after rain has ceased. This study presents a first global estimate of basic statistics rain-induced ocean surface freshening and temperature changes and of their variations with seasons.

How to cite: Bellenger, H., Perrot, X., Guez, L., Duvel, J.-P., Supply, A., Boutin, J., and Reverdin, G.: Global ocean surface stratifications due to rain based on ERA5, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18373,, 2020