Modelling the seasonal dynamics of the Peru-Chile Undercurrent off Central Chile (30–40°S). (15th July 2016)

• Record Type: Journal Article
• Authors: Vergara, Odette A.; Echevín, Vincent; Sepúlveda, Héctor H.; Colas, Francois; Quiñones, Renato A.
• Is Part Of: Continental shelf research. Volume 123(2016)
• Page Start: 61
• Page End: 79
• Publication Date: 2016-07-15
• Subjects: AAIW Antarctic Intermediate Water -- AVHRR Advanced Very High Resolution Radiometer -- AVISO Archiving, Validation and Interpretation of Satellite Oceanographic data -- CARS CSIRO Atlas of Regional Seas -- CCC Chile Coastal Current -- COADS Comprehensive Ocean-Atmosphere Data Set -- CSIRO Commonwealth Scientific and Industrial Research Organisation -- CTW coastal trapped waves -- EBUS Eastern Boundary Upwelling Systems -- EKE Eddy Kinetic Energy -- ESSW Equatorial Subsurface Water -- ETOPO2 Earth Topography and Bathymetry -- EUC Equatorial Undercurrent -- HCS Humboldt Current System -- FIP Fondo de Investigación Pesquera y Acuicultura -- IEKW intraseasonal equatorial Kelvin waves -- KPP K-Profile Parameterization -- PCCC Peru-Chile Countercurrent -- PCUC Peru-Chile Undercurrent -- PDW Pacific Deep Water -- POM Princeton Ocean Model -- ROMS-AGRIF Regional Oceanic Modeling System - Adaptive Grid Refinement in FORTRAN -- SAAW Sub-Antarctic Water -- SCOW Scatterometer Climatology of Ocean Winds -- SLA Sea Level Anomaly -- SSCC Southern Subsurface Countercurrent -- SST Satellite Sea Surface Temperature -- STW Subtropical Water; Ocean modelling -- Poleward subsurface Peru-Chile Undercurrent -- Eastern Boundary Upwelling System -- Humboldt Current System; Continental shelf -- Periodicals; Submarine geology -- Periodicals; 551.41
• DOI: 10.1016/j.csr.2016.04.001
• Languages: English
• ISSNs: 0278-4343

Abstract

Abstract: The seasonal variability of the hydrology and the poleward subsurface Peru-Chile Undercurrent (PCUC) off the central Chilean coast (29–41°S) were examined using a high-resolution regional model. The model realistically reproduced observed sea level variability, such as intense anticyclonic eddies, the offshore intensification of the poleward flow and the reduced nearshore equatorward flow during autumn, as well as the equatorward intensification of nearshore meandering flow during spring. Values for geostrophic eddy kinetic energy were high along the coast between 30° and 37°S, and lower south of this area. The modelled poleward undercurrent showed latitudinal variability in velocity and transport. The maximum average transport reported was 0.8 Sv near 30°S, consistent with previous modelling studies and estimations derived from in situ observations. The poleward reduction in undercurrent strength was shown to be partly generated by the poleward decrease in wind stress curl and by the formation of a westward jet near 35°S associated with westward-propagating eddies. A Lagrangian analysis of the modelled water parcels transported by the undercurrent shows that only 14–20% of the subsurface floats transported by the undercurrent upwelled into the surface layer within the subsequent six months after their release. The floats remaining within the subsurface layer were likely transported further south by the current, offshore by westward-propagating eddies or equatorward by the deeper part of the surface coastal current. Highlights: We analysed the Peru-Chile Undercurrent using a ROMS model. The results were validated using observations from the Eastern South Pacific Region. Poleward decrease in wind stress curl reduces PCUC strength. There is a deepening of the maximum velocity nucleus of the Peru-Chile Undercurrent. Less than 20% of the particles transported by the undercurrent upwell after 6 months.