The Recent Increase in Atlantic Hurricane Activity: Causes and Implications

of the wind stress around the center dates of the new production data. The stresses were either averaged spatially over the same zonal intervals as the new production sections, or were computed at the longitude of new production data for values derived from a single location. The wind stresses were added to the regression of new production on thermocline depth in a stepwise fashion. The incremental improvement to the explained variance (4%) is not statistically different from zero. The reason for the relative lack of improvement when including local zonal wind stress is that large-scale, remotely wind-forced upwelling, as manifest through thermocline depth variations, is the principal physical process driving vertical fluxes of heat and nutrients into the surface layer, rather than local wind-forced upwelling. The primacy of non— local wind—forced dynamics in affecting large-scale thermocline depth variations and surface layer prop