1. Subsurface connections in the eastern tropical Pacific during La Niña 1999–2001 and El Niño 2002–2003
- Author
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Bruno Blanke, Wolfgang Schneider, François Colas, Ivonne Montes, Vincent Echevin, Departamento de Oceanografía [Concepción], Universidad de Concepción - University of Concepcion [Chile], Centro de Investigacion Oceanografica en el Pacifico Sur-Oriental, Institute of Geophysics and Planetary Physics [Los Angeles] (IGPP), University of California [Los Angeles] (UCLA), University of California (UC)-University of California (UC), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de physique des océans (LPO), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Universidad de Concepción [Chile], University of California-University of California, Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris)
- Subjects
Atmospheric Science ,010504 meteorology & atmospheric sciences ,Subsurface currents ,Soil Science ,Aquatic Science ,Oceanography ,01 natural sciences ,010305 fluids & plasmas ,Geochemistry and Petrology ,0103 physical sciences ,Earth and Planetary Sciences (miscellaneous) ,14. Life underwater ,[SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography ,Sea level ,0105 earth and related environmental sciences ,Earth-Surface Processes ,Water Science and Technology ,Tropical pacific ,Ecology ,Paleontology ,Forestry ,Current (stream) ,La Niña ,Sea surface temperature ,Geophysics ,El Niño Southern Oscillation ,El Niño ,13. Climate action ,Space and Planetary Science ,Climatology ,Geology - Abstract
International audience; The subsurface connections between the Equatorial Current System (ECS) and the Peru Current System (PCS) between 1999 and 2005 are investigated with a primitive-equation, eddy-resolving regional model that is forced with realistic atmospheric and lateral oceanic conditions. Specific attention is given to the 1999-2000 La Niña and the 2002-2003 El Niño. The model's skill is assessed through a comparison with satellite-derived sea level anomalies and in situ sea surface temperature time series. The model reproduces fairly well the known dynamics of the region for climatological conditions, and the numerical solution obtained for the particular 1999-2000 and 2002-2003 events presents patterns rather typical of cold and warm phases of El Niño-Southern Oscillation (ENSO). Eulerian and Lagrangian diagnoses are used to derive relevant information about the density and velocity vertical structures of the ECS and the PCS. The transports of the major currents in the region are shown to differ a lot between the 1999-2000 La Niña and the 2002-2003 El Niño. The equatorial subsurface currents transfer significantly more water into the eastern tropical Pacific during La Niña than during El Niño, whereas the Peru-Chile Undercurrent (PCUC) carries more water during El Niño. The equatorial subsurface currents, and especially the primary Southern Subsurface Countercurrent, contribute to 80% of the PCUC transport during the 1999-2000 cold phase. This ratio falls down to only 20% during the 2002-2003 warm phase.
- Published
- 2011
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