Linearity of DMS transfer coefficient with both friction velocity and wind speed in the moderate wind speed range

In many air-sea gas exchange parameterizations, wind speed is the sole environmental controlling factor for exchange velocity, k. Here we examine also the role of friction velocity (u*) in the mid-range of wind speeds, using data from the 2007 Deep Ocean Gas Exchange Experiment. We measured dimethyl sulfide (DMS) fluxes and divided these by the interfacial concentration difference, Delta C-DMS, to derive k. Computed ks are sensitive to spatial gradients in seawater DMS concentration (DMSw). A linear function with either u* or U-10N (wind speed) explains 87% of the variance in k. Lower and higher winds will have different physics and curvature in transitions between ranges. This linearity demonstrates that a simple physical model of wind-driven stirring is sufficient for DMS in the wind speed range U-10N = 4-12 m/s. A non-linear relationship to wind speed would be superfluous and obscures the physics. Citation: Huebert, B. J., B. W. Blomquist, M. X. Yang, S. D. Archer, P. D. Nightingale, M. J. Yelland, J. Stephens, R. W. Pascal, and B. I. Moat (2010), Linearity of DMS transfer coefficient with both friction velocity and wind speed in the moderate wind speed range, Geophys. Res. Lett., 37, L01605, doi: 10.1029/2009GL041203.