The seasonal California Undercurrent variability off Baja California: A numerical model

Abstract:

We have analyzed the coastal circulation variability off Baja California using a hydrostatic numerical model. Our numerical implementation reproduces the regional coastal dynamics, characterized by an equatorward surface California Current and a subsurface poleward California Undercurrent (CU) that flowed over the continental slope with stronger velocities between the 26.3 and 26.6 isopicnals. The seasonal variability of this poleward flow was governed by an energetic semiannual component that induced stronger velocities during June-July and October-November, when the CU reached mean speeds of ~10 cm/s. The semiannual CU component dominated the main empirical mode of variability of the subsurface coastal circulation. Numerical experiments and the alongshore correlation of the subsurface coastal velocity revealed that the energetic semiannual CU variability was induced by the propagation of coastal-trapped waves generated in the Tropical Pacific.