The effects of climatological and transient wind forcing on eddy generation in the California current system

Abstract

A high-resolution, multi-level, primitive equation ocean model is used to examine the response to transient and climatological wind forcing of an idealized, flat-bottomed oceanic regime on a β-place, along an eastern boundary. An annually periodic wind forcing function with zonal variability is used as transient forcing in several experiments using both winter and summer initializations. When the curl component of the forcing is stronger than the stress, as in the wintertime, a surface poleward flow develops in the nearshore region with a equatorward flow offshore. When wind stress dominates the forcing, as in the summertime, a coastal jet develops with an undercurrent. In other experiments, spatially varying one degree and two tenths degree steady wind stress data are used as the climatological forcing. The one degree climatological wind stress data has positive curl at the coast which causes a poleward surface flow to develop. When two tenths degree wind stress data is used in the nearshore area, both positive and negative curl in the coastal region result in the formation of poleward and equatorward currents, respectively. As a result of convergence in the surface flow, eddies and a well defined cold filament develop. These results show that the interaction of diverse coastal currents driven by an equally diverse wind field can play an important role in the production of cold filaments and eddies.