November 13, 2007: “Variation in ocean surface temperature due to near surface flow: Straining the cool skin layer"
Andrew Wells, Institute of Theoretical Geophysics, DAMTP, University of Cambridge
The aqueous thermal boundary layer near to the ocean surface, or skin layer, has thickness O(1mm) and plays an important role in controlling the exchange of heat between atmosphere and ocean, and its dynamics can be modified by near surface flows. We present a quantitative experimental investigation of the dynamics of the skin layer in the presence of local upwelling. A non-dimensional formulation is presented that identifies different dynamical regimes for the skin layer with corresponding differences in surface temperature, or skin temperature. In laboratory experiments, we observe an increase in skin temperature above regions of upwelling flow, and show that previous
theories accurately describe the observed difference between the skin and interior temperature for large Peclet numbers. The non-dimensional formulation allows us to predict that straining of the
cool skin by internal waves is unlikely to be responsible for large changes in skin temperature. However, this formulation may prove to be important in the description of other scalars, such as the transfer of gases between the ocean and atmosphere.