title: Ageostrophic Frontal Processes Controlling Phytoplankton Production in the Catalano-Balearic Sea (Western Mediterranean).
abstract: Buoyancy-induced unstable boundary currents and the accompanying retrograde density fronts are often the sites of pronounced mesoscale activity, ageostrophic frontal processes, and associated high biological production in marginal seas. Biophysical model simulations of the Catalano-Balearic Sea (Western Mediterranean) illustrated that the unstable and nonlinear southward frontal boundary current along the Spanish coast resulted in a strain-driven frontogenesis mechanism. High upwelling velocities of up to 80 m d(-1) injected nutrients into the photic layer and promoted enhanced production on the less dense, onshore side of the front characterized by negative relative vorticity. Additional down-front wind stress and heat flux (cooling) intensified boundary current instabilities and thus ageostrophic cross-frontal circulation and augmented production. Specifically, entrainment of nutrients by relatively strong buoyancy-induced vertical mixing gave rise to a more widespread phytoplankton biomass distribution within the onshore side of the front. Mesoscale cyclonic eddies contributed to production through an eddy pumping mechanism, but it was less effective and more limited regionally than the frontal processes. The model was configured for the Catalano-Balearic Sea, but the mechanisms and model findings apply to other marginal seas with similar unstable frontal boundary current systems.
authors.affiliation: SOCIB, Balearic Islands Coastal Ocean Observing and Forecasting System, Parc Bit, Norte, Bloc A, Palma de Mallorca, Spain; Middle East Technical University, Institute of Marine Sciences, 33731 Erdemli, Mersin, Turkey.
authors.forename: Temel
authors.initials: T
authors.lastname: Oguz
authors.affiliation: European Commission, Joint Research Centre, Institute for Environment and Sustainability, Water Resources Unit, Via E. Fermi, 2749, Ispra, Italy.
authors.forename: Diego
authors.initials: D
authors.lastname: Macias
authors.affiliation: SOCIB, Balearic Islands Coastal Ocean Observing and Forecasting System, Parc Bit, Norte, Bloc A, Palma de Mallorca, Spain; IMEDEA (CSIC-UIB), Miquel Marquès 21, 07190 Esporles, Spain.
authors.forename: Joaquin
authors.initials: J
authors.lastname: Tintore
mesh_terms: D002734:Chlorophyll / Q000378:metabolism; D019083:Mediterranean Region; D008962:Models, Theoretical; D009792:Oceans and Seas; D010839:Phytoplankton / Q000378:metabolism*
chemical_list: D002734:Chlorophyll