Of The Effect Of Mesoscale Structures On The Deep Chlorophyll And Particle Maxima At The Entrance To The Gulf Of California

HR: 0800h
AN: OS11B-0503 [Abstracts]
TI: Of The Effect Of Mesoscale Structures On The Deep Chlorophyll And Particle Maxima At The Entrance To The Gulf Of California
AU: * Jaimes, A
EM: ajaimes07@gmail.com
AF: Centro de Investigaciones Biológicas del Noroeste, S.C., Mar Bermejo No. 195, Col. Playa Palo de Santa Rita, La Paz, BCS 23090, Mexico
AU: Trasviña, A
EM: trasvi@cicese.mx
AF: Centro de Investigación cientifica y de Educación Superior de Ensenada BCS, Miraflores # 334, Fracc. Bella Vista., La Paz, BCS 23050, Mexico
AU: Maske, H
EM: hmaske@cicese.mx
AF: Centro de Investigación Superior y Científica de Ensenada, BC. (CICESE, BC., MEXICO), Km. 107 carreteras Tijuana-Ensenada, Ensenada, BC 22860, Mexico
AB: The entrance to the Gulf of California is characterized by the convergence of three surface water masses resulting in a complex mesoscale field. The effects of such structures on the deep chlorophyll maximum, an ubiquitous feature of many oceanic regions, is not well known. An interdisciplinary oceanographic survey was carried out in February-March 2005. The main goal was to study the effect of mesoscale eddies on the biology of an oligotrophic ocean. Several cyclonic and anticyclonic structures were found as well as a narrow and intense current jet off the coast of Baja California. Inside cyclonic/anticyclonic eddies a relative increase/decrease of both chlorophyll and dissolved oxygen concentration is clearly observed. The deep chlorophyll maximum is found positioned above the thermocline throughout the survey. Higher concentrations are found inside the deep chlorophyll maximum inside the cyclonic eddy and in the deep chlorophyll maximum of the coastal jet. The latter case is consistent with the enhancement of chlorophyll concentrations by advective processes. This confirms that advection plays an important role in the enhancement observed inside such mesoscale structures. These eddies are advecting cold, upwelling-enriched California Current waters. Anticyclonic eddies show the opposite behavior because they contain warm tropical waters, typically poor in nutrients and low in chlorophyll concentrations. A one-dimensional model is used to determine the effect of dynamical variations generated by mesoscale structures, when growth balances the sinking of phytoplankton in a mixed vertical structure within the surface mixed layer, model results suggest that vertical diffusion is an important mechanism capable of diluting phytoplankton concentrations.
DE: 4223 Descriptive and regional oceanography
DE: 4283 Water masses
DE: 4520 Eddies and mesoscale processes
DE: 4855 Phytoplankton
DE: 4899 General or miscellaneous
SC: Ocean Sciences [OS]
MN: 2007 Fall Meeting