Search

ISI Document Delivery No.: 148GS Times Cited: 1 Cited Reference Count: 78 Cited References: Ando K, 1997, J GEOPHYS RES-OCEANS, V102, P23063, DOI 10.1029/97JC01443 Ashok K, 2007, J GEOPHYS RES-OCEANS, V112, DOI 10.1029/2006JC003798 BLANCHOT J, 1992, J PLANKTON RES, V14, P137, DOI 10.1093/plankt/14.1.137 Bonjean F, 2002, J PHYS OCEANOGR, V32, P2938, DOI 10.1175/1520-0485(2002)0322.0.CO;2 Bonnet S, 2009, GLOBAL BIOGEOCHEM CY, V23, DOI 10.1029/2008GB003439 Bosc C, 2009, J GEOPHYS RES-OCEANS, V114, DOI 10.1029/2008JC005187 Christian JR, 2004, DEEP-SEA RES PT II, V51, P209, DOI 10.1016/j.dsr2.2003.06.002 Cravatte S, 2009, CLIM DYNAM, V33, P565, DOI 10.1007/s00382-009-0526-7 DANDONNEAU Y, 1992, J GEOPHYS RES-OCEANS, V97, P3581, DOI 10.1029/91JC02848 DANDONNEAU Y, 1979, OCEANOL ACTA, V2, P133 Montegut CD, 2004, J GEOPHYS RES-OCEANS, V109, DOI 10.1029/2004JC002378 Dupouy C., 1993, REMOTE SENSING OCEAN, P406 Eldin G, 1997, DEEP-SEA RES PT II, V44, P1783, DOI 10.1016/S0967-0645(97)00023-4 Gierach MM, 2012, GEOPHYS RES LETT, V39, DOI 10.1029/2012GL051103 Harrison DE, 1997, J CLIMATE, V10, P3131, DOI 10.1175/1520-0442(1997)0102.0.CO;2 Hasegawa T, 2009, J OCEANOGR, V65, P817 Hasegawa T, 2011, J PHYS OCEANOGR, V41, P827, DOI 10.1175/2010JPO4421.1 Hasegawa T, 2010, OCEAN DYNAM, V60, P1255, DOI 10.1007/s10236-010-0334-y HERBLAND A, 1979, J MAR RES, V37, P87 Higgins HW, 2006, DEEP-SEA RES PT I, V53, P1845, DOI 10.1016/j.dsr.2006.09.001 Inoue HY, 1996, GEOPHYS RES LETT, V23, P1781, DOI 10.1029/96GL01674 Kao HY, 2009, J CLIMATE, V22, P615, DOI 10.1175/2008JCLI2309.1 Karl DM, 1996, DEEP-SEA RES PT II, V43, P129, DOI 10.1016/0967-0645(96)00005-7 Kozai K, 2004, ADV SPACE RES-SERIES, V33, P1189, DOI 10.1016/S0273-1177(03)00371-5 Kug JS, 2009, J CLIMATE, V22, P1499, DOI 10.1175/2008JCLI2624.1 Kuroda Y, 2000, J OCEANOGR, V56, P103, DOI DOI 10.1023/A:1011122810354 Le Borgne R, 1997, DEEP-SEA RES PT II, V44, P2003, DOI 10.1016/S0967-0645(97)00034-9 Le Borgne R, 2002, DEEP-SEA RES PT II, V49, P2471, DOI 10.1016/S0967-0645(02)00045-0 LEBOUTEILLER A, 1992, DEEP-SEA RES, V39, P805, DOI 10.1016/0198-0149(92)90123-B Lehodey P, 2001, PROG OCEANOGR, V49, P439, DOI 10.1016/S0079-6611(01)00035-0 Lehodey P, 1997, NATURE, V389, P715, DOI 10.1038/39575 Leonard CL, 1996, INT J REMOTE SENS, V17, P721 Letelier RM, 1996, DEEP-SEA RES PT II, V43, P467, DOI 10.1016/0967-0645(96)00006-9 LEVITUS S, 1993, PROG OCEANOGR, V31, P245, DOI 10.1016/0079-6611(93)90003-V LEWIS MR, 1990, NATURE, V347, P543, DOI 10.1038/347543a0 Longhurst AR, 2007, ECOLOGICAL GEOGRAPHY LUKAS R, 1991, J GEOPHYS RES-OCEANS, V96, P3343 Lukas R., 1988, P US TOGA W PAC AIR, P43 Mackey DJ, 1997, DEEP-SEA RES PT II, V44, P1951, DOI 10.1016/S0967-0645(97)00033-7 MACKEY DJ, 1995, DEEP-SEA RES PT II, V42, P499, DOI 10.1016/0967-0645(95)00038-R Maes C, 2004, GEOPHYS RES LETT, V31, DOI 10.1029/2004GL019867 Maes C, 2006, GEOPHYS RES LETT, V33, DOI 10.1029/2005GL024772 Maes C, 2002, GEOPHYS RES LETT, V29, DOI 10.1029/2002GL016029 Matsumoto K, 2004, DEEP-SEA RES PT I, V51, P1851, DOI 10.1016/j.dsr.2004.07.015 Matsumoto K, 2009, J MARINE SYST, V75, P245, DOI 10.1016/j.jmarsys.2008.10.007 McClain CR, 2004, DEEP-SEA RES PT II, V51, P281, DOI 10.1016/j.dsr2.2003.08.002 McClain CR, 2002, DEEP-SEA RES PT II, V49, P2533, DOI 10.1016/S0967-0645(02)00047-4 McClain CR, 2004, DEEP-SEA RES PT II, V51, P5, DOI 10.1016/j.dsr2.2003.11.001 McPhaden MJ, 1998, J GEOPHYS RES-OCEANS, V103, P14169, DOI 10.1029/97JC02906 Messie M, 2006, DEEP-SEA RES PT I, V53, P1581, DOI 10.1016/j.dsr.2006.06.007 Milliman JD, 1999, J SEA RES, V41, P97, DOI 10.1016/S1385-1101(98)00040-9 Montegut CD, 2007, J GEOPHYS RES-OCEANS, V112, DOI 10.1029/2006JC003953 Murakami H, 2000, J GEOPHYS RES-OCEANS, V105, P19551, DOI 10.1029/2000JC900091 Murtugudde RG, 1999, J GEOPHYS RES-OCEANS, V104, P18351, DOI 10.1029/1999JC900135 O'Carroll AG, 2006, J ATMOS OCEAN TECH, V23, P1573, DOI 10.1175/JTECH1934.1 Picaut J, 2001, J GEOPHYS RES-OCEANS, V106, P2363, DOI 10.1029/2000JC900141 Picaut J, 1996, SCIENCE, V274, P1486, DOI 10.1126/science.274.5292.1486 Radenac MH, 2010, DEEP-SEA RES PT I, V57, P1314, DOI 10.1016/j.dsr.2010.06.004 Radenac MH, 2001, J GEOPHYS RES-OCEANS, V106, P26879, DOI 10.1029/2000JC000546 Radenac MH, 2012, J GEOPHYS RES-OCEANS, V117, DOI 10.1029/2011JC007841 Radenac MH, 1996, DEEP-SEA RES PT II, V43, P725, DOI 10.1016/0967-0645(96)00025-2 Radenac MH, 2005, OCEAN DYNAM, V55, P34, DOI 10.1007/s10236-005-0111-5 REVERDIN G, 1994, J GEOPHYS RES-OCEANS, V99, P20323, DOI 10.1029/94JC01477 Reynolds RW, 2010, J CLIMATE, V23, P152, DOI 10.1175/2009JCLI3252.1 Rodier M., 2000, J OCEANOGR, V56, P463, DOI 10.1023/A:1011136608053 SIEGEL DA, 1995, J GEOPHYS RES-OCEANS, V100, P4885, DOI 10.1029/94JC03128 Stoens A, 1999, J GEOPHYS RES-OCEANS, V104, P3323, DOI 10.1029/98JC02713 Torrence C, 1998, B AM METEOROL SOC, V79, P61, DOI 10.1175/1520-0477(1998)0792.0.CO;2 Turk D, 2001, J GEOPHYS RES-OCEANS, V106, P4501, DOI 10.1029/1999JC000058 Turk D, 2001, SCIENCE, V293, P471, DOI 10.1126/science.1056449 Turk D, 2011, GEOPHYS RES LETT, V38, DOI 10.1029/2011GL049674 Ueki I, 2003, J GEOPHYS RES-OCEANS, V108, DOI 10.1029/2002JC001611 Vialard J, 1998, J PHYS OCEANOGR, V28, P1089, DOI 10.1175/1520-0485(1998)0282.0.CO;2 Wang XJ, 2009, BIOGEOSCIENCES, V6, P2647 Wilson C, 2001, J GEOPHYS RES-OCEANS, V106, P31175, DOI 10.1029/2000JC000724 WYRTKI K, 1984, J PHYS OCEANOGR, V14, P242, DOI 10.1175/1520-0485(1984)0142.0.CO;2 Wyrtki K., 1989, P W PAC INT M WORKSH, P99 YAN XH, 1992, SCIENCE, V258, P1643, DOI 10.1126/science.258.5088.1643 Radenac, Marie-Helene Messie, Monique Leger, Fabien Bosc, Christelle CNES (Ocean Surface Topography Science Team program); CNES We thank the Ocean Biology Processing Group at the GSFC (http://oceancolor.gsfc.nasa.gov) for the production and distribution of the ocean color data. We also acknowledge Coriolis (http://www.coriolis.eu.org), AVISO (http://www.aviso.oceanobs.com/duacs), the CERSAT (http://cersat.ifremer.fr), OSCAR (http://www.oscar.noaa.gov), and RSS (http://www.ssmi.com), for sharing the freely available data we used. We are grateful to Thierry Delcroix for constructive discussions during this work We thank three anonymous reviewers for their very valuable remarks. This work was supported by CNES (Ocean Surface Topography Science Team program). F. L benefited from CNES funding. 1 ELSEVIER SCIENCE INC NEW YORK REMOTE SENS ENVIRON; The analysis of the SeaWiFS chlorophyll archive shows a quasi-persistent strip of oligotrophic waters (chl < 0.1 mg m(-3)) extending over about 20 degrees longitude in the eastern part of the equatorial Pacific warm pool. Other space-borne data sets (scatterometric wind, microwave sea surface temperature (SST), altimetric sea level, and surface currents) were used together with barrier layer thickness derived from Argo floats to investigate the variability of the oligotrophic zone and of its eastern and western boundaries, and to propose processes that could explain why surface chlorophyll is so low in this region. The eastern limit of the oligotrophic waters matches the eastern edge of the warm pool and moves zonally both at seasonal time scale and with the El Nino/La Nina phases whereas the western limit moves mostly at intraseasonal and interannual time scales. On average, about half of the surface of the zone is occupied by very oligotrophic waters (chl < 0.07 mg m(-3)) located in the eastern part. The degree of oligotrophy of the zone increases when its width is maximum during boreal fall and winter and during El Nino events. Oligotrophy in the eastern part of the warm pool most likely persists because of the lack of vertical or horizontal penetration of nutrient-rich water due to the following processes. 1/ The equatorial oligotrophic warm pool is bounded poleward by the oligotrophic subtropical gyres. 2/The deep nutrient pool prevents strong vertical nutrient inputs into the euphoric layer and the barrier layer above it potentially reduces the efficiency of mixing. 3/ During westerly wind events, mesotrophic waters in the far western basin are too distant from the oligotrophic zone to be efficient nutrient and phytoplankton sources, and become nutrient and phytoplankton depleted during their eastward advection. 4/ Nutrient-rich waters from the central basin and nutrient-poor surface waters of the warm pool do not blend because of subduction at the eastern limit of the oligotrophic zone.

International audience; Major features of the equatorial portion of the western Pacific warm pool (WP) were brought to light through the analysis of an unprecedented collection of temperature and salinity profiles derived from Argo floats from 2000 to 2007. A region of thick (>15–25 m) and quasi-permanent barrier layers (BLs) was found to occur in a band from 10° to 20° longitude to the west of the maximum zonal sea surface salinity gradient (∂S/∂x), which occurs at the eastern edge of the WP. In this region, thick BLs and associated maxima (∂S/∂x) were displaced eastward (westward) during El Niño (La Niña) over a distance of more than 6000 km. The thickness of the BL in this region is, to the first order, proportional to ∂S/∂x and quasi-permanently associated with the occurrence of sea surface temperatures warmer than 28–29°C, which are a good proxy for maximum atmospheric convection for the current Pacific climate. Statistics indicated that a thick BL forms preferentially under low wind conditions, heavy precipitation, eastward advection of low sea surface salinity, zonal current vertical shear, and/or in conjunction with equatorial downwelling Kelvin and Rossby waves (favoring the vertical stretching of the upper water column). None of these processes seemed to dominate the others, indicating that the formation of a thick BL results from a combination of different and complex mechanisms. The fact that a thick BL represents a quasi-permanent feature in the WP signifies that its specific stratification and likely impact on the sea surface temperature balance should be accounted for in coupled models.

[1] Modifications of the volume of warm water above the thermocline in the equatorial Pacific are thought to be critical for ENSO (El Nino Southern Oscillation) preconditioning, development and prediction. In this paper, changes in this Warm Water Volume (WWV) are first reviewed from the literature, and then analyzed within 5°N–5°S in using 1992–2006 altimeter-derived sea level anomalies (SLA) and in situ observations. We conclude that the 1992–2006 WWV changes in the equatorial band are a residual from the opposite effects of zonally integrated meridional Ekman and geostrophic transports of warm water, the latter being estimated from SLA and validated against in situ observations. For the first time with observations, we evidence first baroclinic first meridional mode equatorial Rossby waves to be responsible for the anomalous meridional geostrophic transports of warm water, in changing the basin-scale zonal pressure gradient. These transports appear in phase opposition and proportional to the anomalous Sea Surface Temperature (SST) in the region NINO3.4 (170°W–120°W, 5°N–5°S). The links between our observational results and the recharge/discharge oscillator theory, the differences in WWV between ENSO events, and the hint for possible recent changes in the relation between WWV and NINO3.4 SST are discussed.