Low Frequency Variability from Altimetry and In Situ Observations off the Pacific Coast of Southern Baja California
Trasvi–a-Castro, Armando1; Gaxiola-Castro, Gilberto2; Zaitzev, Oleg3
1CICESE, Unidad La Paz, MEXICO; 2CICESE, Departamento de Ocanograf’a Biol—gica, MEXICO; 3CICIMAR, IPN, MEXICO
Every summer the Pacific coast of Southern Baja California experiences a dramatic change in oceanographic conditions. The usually cool mid-latitude conditions, more typical of the Southern California coastline, meet warm tropical waters that propagate poleward of the Mexican Pacific Warm Pool. Most of the year the west coast of Baja California is influenced by intense equatorward winds parallel to the coast, thus creating the right conditions for coastal upwelling. From the spring to the beginning of the summer the entrance to Magdalena Bay (24 N) and Tortugas Bay (27 N), for instance, are sites of intense subtropical upwelling. This creates the conditions for a coastal ocean capable of sustaining important fisheries. Starting in September a poleward flow introduces warm tropical waters to the coastal region. The current often flows against prevailing Northwesterly winds and its presence inhibits upwelling and coastal productivity. This work presents results of an observational program that includes data from several oceanographic campaigns. Time series of coastal sea level and currents are used to validate data at several altimetry sites off the coast. Altimetry and in situ time series are used to characterize the low frequency variability of the coastal flow.