Sea-state dependent exchange coefficients under strongly stable atmosphere

The standard Monin-Obukhov theory predicts that the exchange coefficients for momentum, heat, and moisture become small when the atmosphere becomes very stable (for wind speeds up to say 7 m/s). Theory also predicts that the gradient, e.g. shear, becomes large at the sea surface. The generation of surface waves depends more on the actual wind speed at a certain height, than the turbulence levels in the atmosphere. The case with very stable atmosphere is a common phenomenon in spring for semi-enclosed basins and lakes, or situations with upwelling of cold water. Here we consider the role of oceanic surface waves for the exchange of properties between the atmosphere and a cold water surface by extending the Monin-Obukhov framework to also include growth of surface waves. We exemplify the how the proposed mechanism will be important for evaluating dynamics in spring, and how it influences upwelling in a large lake (lake Vänern) in Sweden.