Diurnal Surface Flux Variability Over Western Boundary Currents

An analysis of a satellite ocean surface turbulent flux product demonstrated that, as expected, the western boundary current regions dominate the seasonal cycle amplitude. Surprisingly, our analysis of the global ocean diurnal flux variability also demonstrated a regional maximum in the winter over the western boundary current regions. We conducted comparisons with in situ data from several buoys located in these regions. The buoy data were in general agreement with the relative magnitude, timing, and importance of each of the bulk parameters driving the latent and sensible heat fluxes. Further analysis demonstrated that the strength and timing of the diurnal signal is related to the location of the buoy relative to the region of maximum heat flux and sea surface temperature gradient. In both regions, the timing of the higher winds coincides with the moistest surface layer, indicating that surface fluxes rather than entrainment mixing play a key role in this phenomenon.