Circulation Patterns Of The Southern Bay Of Biscay During A Winter-Spring Transition Period

Paula C. Pardo, Manuel Ruiz Villarreal and Pablo Otero Tranchero
Instituto Español de Oceanografía.
Centro Oceanográfico de A Coruña.


Circulation in the northern Iberian coast (shelf and slope) has been studied for the transition period between winter and spring 2006. The effects of the interaction between wind events and the hydrographic conditions over the shelf have been analysed with ROMS_AGRIF simulations. River plumes, with noticeable relevance in winter, were also taken into account for the experiments and the different evolution of them during upwelling (downwelling) pulses was studied. In this way, the nesting technique of ROMS allows for an effective way of getting better perfromances at the high resolution domain (1.8km) from an ocean domain (15km resolution). ROMS was forced with the local meteorological model MM5 (30km resolution) in both analitical and predictive experiments. A predictive simulation was succesfully performed from May-2006 on. Circulation during winter was characterized by a Poleward slope flow of considerable strength favoured by strong wind pulses, which acts as a wall for the spreading of river plumes. This circulation pattern reverses in spring, when the river run-off reduces. Salinity, temperature and velocity fields were compared with currentmeter (Cabo Peñas, southwestern Bay of Biscay) and CTD data (cruises in Asturias shelf) with good agreement.