Please use this identifier to cite or link to this item: http://hdl.handle.net/10553/43840
Title: Diurnal-inertial motions and diapycnal mixing on the Portuguese shelf
Authors: Aguiar González, Miguel Borja 
Rodríguez Santana, Ángel 
Cisneros Aguirre, Jesús 
Martínez Marrero, Antonio 
UNESCO Clasification: 251007 Oceanografía física
Keywords: Diurnal-inertial motions
Diurnal wind forcing
Diapycnal mixing
Bay of Setúbal
Issue Date: 2011
Project: Procesos de Mezcla en la Cuenca Canaria: Corriente de Canarias y Sistema de Afloramiento Del Noroeste Africano. 
Campaña Oceanográfica Promeca-2010 
Journal: Continental Shelf Research 
Abstract: This work presents observations of diurnal–inertial motions forced by a sea–land breeze regime near critical latitudes () for resonance on the Portuguese shelf. Wind conditions were determined with an Aanderaa meteorological buoy placed in the Bay of Setúbal during the Maritime Rapid Environmental Assessment 2004 (MREA04) sea trial. Currents data for this period were recorded from two Barny ADCP (acoustic Doppler current profiler) deployments located on the north and south sides of the bay, respectively. Both ADCPs covered almost the full depth of water (⁓ 112 m) with 24 bins of 4 m size at both sites. Dominant motions exhibited a two-layer configuration in response to energetic out-of-phase oscillations driven by diurnal–inertial currents. Hence, simultaneous CTD (conductivity, temperature, depth) data were considered to assess the strength of observed motions in promoting diapycnal mixing. With this aim, ADCP and CTD data were used to analyse the vertical shear (S2), squared buoyancy frequency (N2) and gradient Richardson number (Ri) of the water column in terms of two main layers with highly stratified and vertically sheared flows during diurnal–inertial events. Observations show a strong variation in the vertical density field near both ADCP deployments that involved high vertical shears distributed into two layers associated with diurnal–inertial currents. The results of our analysis highlight the role of wind-forced diurnal–inertial motions in shelf areas near the critical latitudes, where they can greatly contribute to triggering diapycnal mixing at the scale of a few days, owing to sea–land breeze forcing.
URI: http://hdl.handle.net/10553/43840
ISSN: 0278-4343
DOI: 10.1016/j.csr.2011.04.015
Source: Continental Shelf Research [ISSN 0278-4343], v. 31 (11), p. 1193-1201
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