Capes and form drag: the role of stratification
Marcello G. Magaldi (1), Tamay M. Özgökmen (1), Annalisa Griffa (1), Eric P. Chassignet (2), Hartmut Peters (1) and Mohamed Iskandarani (1)
1) RSMAS, University of Miami
2) COAPS, Florida State University
Headlands and capes are important topographic features affecting the dynamics of the coastal circulation. Formation of eddies behind these features may have biological and ecological consequences, by trapping of pollutants as well as floating organisms and nutrients. From a more physical point of view, capes and headlands are associated with enhanced mixing, drag and dissipation. Phenomena like current separation, lee waves and generation of leeward eddies result in a drag force imparted on the larger scale flow.
The effect of stratification on the generation of lee eddies and on the energy extracted from the larger scale flow can benefit from further investigation. Here we present a sensitivity study of the dynamics of a steady barotropic current impinging on an idealized headland. Numerical experiments are conducted using ROMS in a wide range of parameters, represented by the Burger number, Rossby number and the slope of the cape. We quantify the form drag exerted by the cape on the coastal current and mixing downstream. We find a clear relation between form drag and the Burger number.