Effects of topographic variability on the formation of upwelling centers off New Jersey: A theoretical model

A theoretical wind-driven, continuously stratified coastal ocean model with varying topography is developed to examine the formation of upwelling cent ers in coastal oceans, such as those observed along the New Jersey coast. I n this simple model an Ekman transport layer is induced by a wind-driven sh ear friction profile to force the coastal ocean. An analytical perturbation solution, including a component of internal Kelvin waves, is solved for th e coastal upwelling system with weak alongshore-varying topography. Under u niformly upwelling favorable winds, the model solutions show that alongshor e-varying topography leads to the formation of upwelling centers along the coast by increasing upwelling on the downslope sides of topographic highs a nd decreasing upwelling on the upslope sides of topographic highs, similar to the observed features off the New Jersey coast during summer seasons. A conservation theorem is derived that indicates the topographic variation do es not change the total amount of upwelled water but redistributes it uneve nly along the coast to form enhanced upwelling centers. The theory suggests that alongshore-varying topography plays an important role in controlling the formation of upwelling centers as it enhances upwelling at some locatio ns and induces downwelling at others. In addition, the variations of the up welling fronts are further complicated by the topographically trapped Kelvi n waves.