The Perú-Chile undercurrent and the oxigen minimum zone variability off central Chile

Ten years of continuous current meter recordings near the core of the Peru-Chile Undercurrent (PCU) over the continental slope at 30°S off Chile, local and equatorial wind stress data, and monthly oceanographic sections off Valparaíso (33°S) are used to study the variability of the PCU and the Oxyge...

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Autores principales: Hormazábal,Samuel, Shaffer,Gary, Silva,Nelson, Navarro,Eduardo
Lenguaje:English
Publicado: Facultad de Ciencias Naturales y Oceanográficas, Universidad de Concepción 2006
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Acceso en línea:http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-65382006000300009
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spelling oai:scielo:S0717-653820060003000092007-10-30The Perú-Chile undercurrent and the oxigen minimum zone variability off central ChileHormazábal,SamuelShaffer,GarySilva,NelsonNavarro,Eduardo Rossby waves oxygen minimum zone El Niño/La Niña cycles Peru-Chile Undercurrent Ten years of continuous current meter recordings near the core of the Peru-Chile Undercurrent (PCU) over the continental slope at 30°S off Chile, local and equatorial wind stress data, and monthly oceanographic sections off Valparaíso (33°S) are used to study the variability of the PCU and the Oxygen Minimum Zone (OMZ) off Chile. The physics that governs the PCU variability differs for intraseasonal periods and for longer periods: Coastal trapped waves dominate the intraseasonal band whereas Rossby waves dominate for periods greater than about 120 days. Semiannual and annual period fluctuations can largely be explained by Rossby waves forced by equatorial Kelvin waves and local winds. Seasonal variations in the PCU are strongly modulated over El Niño/La Niña cycles. During warm El Niño events, the PCU undergoes strong, semiannual variability whereas during La Niña events, annual variability dominates. These results together with oceanographic sections off Valparaíso suggest that Rossby waves provide a physical mechanism to explain a significant fraction of seasonal variability observed in the OMZ. During the downwelling (upwelling) phase of these waves the poleward (equatoward) flow is stronger (90° out of phase with respect to sea level), the isotherms are deeper (shallower), the OMZ thickness increases (decreases), the mean concentration of salinity and silicate increases (decreases) and oxygen concentration and nitrate deficit decrease (increase) in the OMZ.info:eu-repo/semantics/openAccessFacultad de Ciencias Naturales y Oceanográficas, Universidad de ConcepciónGayana (Concepción) v.70 suppl.1 20062006-10-01text/htmlhttp://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-65382006000300009en10.4067/S0717-65382006000300009
institution Scielo Chile
collection Scielo Chile
language English
topic Rossby waves
oxygen minimum zone
El Niño/La Niña cycles
Peru-Chile Undercurrent
spellingShingle Rossby waves
oxygen minimum zone
El Niño/La Niña cycles
Peru-Chile Undercurrent
Hormazábal,Samuel
Shaffer,Gary
Silva,Nelson
Navarro,Eduardo
The Perú-Chile undercurrent and the oxigen minimum zone variability off central Chile
description Ten years of continuous current meter recordings near the core of the Peru-Chile Undercurrent (PCU) over the continental slope at 30°S off Chile, local and equatorial wind stress data, and monthly oceanographic sections off Valparaíso (33°S) are used to study the variability of the PCU and the Oxygen Minimum Zone (OMZ) off Chile. The physics that governs the PCU variability differs for intraseasonal periods and for longer periods: Coastal trapped waves dominate the intraseasonal band whereas Rossby waves dominate for periods greater than about 120 days. Semiannual and annual period fluctuations can largely be explained by Rossby waves forced by equatorial Kelvin waves and local winds. Seasonal variations in the PCU are strongly modulated over El Niño/La Niña cycles. During warm El Niño events, the PCU undergoes strong, semiannual variability whereas during La Niña events, annual variability dominates. These results together with oceanographic sections off Valparaíso suggest that Rossby waves provide a physical mechanism to explain a significant fraction of seasonal variability observed in the OMZ. During the downwelling (upwelling) phase of these waves the poleward (equatoward) flow is stronger (90° out of phase with respect to sea level), the isotherms are deeper (shallower), the OMZ thickness increases (decreases), the mean concentration of salinity and silicate increases (decreases) and oxygen concentration and nitrate deficit decrease (increase) in the OMZ.
author Hormazábal,Samuel
Shaffer,Gary
Silva,Nelson
Navarro,Eduardo
author_facet Hormazábal,Samuel
Shaffer,Gary
Silva,Nelson
Navarro,Eduardo
author_sort Hormazábal,Samuel
title The Perú-Chile undercurrent and the oxigen minimum zone variability off central Chile
title_short The Perú-Chile undercurrent and the oxigen minimum zone variability off central Chile
title_full The Perú-Chile undercurrent and the oxigen minimum zone variability off central Chile
title_fullStr The Perú-Chile undercurrent and the oxigen minimum zone variability off central Chile
title_full_unstemmed The Perú-Chile undercurrent and the oxigen minimum zone variability off central Chile
title_sort perú-chile undercurrent and the oxigen minimum zone variability off central chile
publisher Facultad de Ciencias Naturales y Oceanográficas, Universidad de Concepción
publishDate 2006
url http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-65382006000300009
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