Meridional Overturning Circulation Transport Variability at 34.5 degrees S During 2009-2017: Baroclinic and Barotropic Flows and the Dueling Influence of the Boundaries

Type Article
Date 2018-05-01
Language English
Author(s) Meinen Christopher S.1, Speich Sabrina2, Piola Alberto R.3, 4, 5, Ansorge Isabelle6, 7, Campos Edmo8, 9, Kersale Marion1, 10, Terre Terrillon Thierry11, Chidichimo Maria Paz3, 5, Lamont Tarron6, 7, 12, Sato Olga T.8, Perez Renellys C.1, Valla Daniel3, 5, Van Den Berg Marcel12, Le Henaff Matthieu1, 10, Dong Shenfu1, Garzoli Silvia L.1, 10
Affiliation(s) 1 : Atlantic Oceanog & Meteorol Lab, Miami, FL 33149 USA.
2 : Ecole Normale Super, IPSL, Lab Meteorol Dynam, Paris, France.
3 : Serv Hidrog Naval, Buenos Aires, DF, Argentina.
4 : Univ Buenos Aires, Dept Ciencias Atmosfera & Oceanos, Buenos Aires, DF, Argentina.
5 : Consejo Nacl Invest Cient & Tecn, Inst Francoargentino Estudios Clima & Sus Impacto, Buenos Aires, DF, Argentina.
6 : Univ Cape Town, Oceanog Dept, Rondebosch, South Africa.
7 : Univ Cape Town, Marine Res Inst, Rondebosch, South Africa.
8 : Univ Sao Paulo, Oceanog Inst, Sao Paulo, Brazil.
9 : Univ Fed Ceara, Ocean Sci Lab, Fortaleza, Ceara, Brazil.
10 : Univ Miami, Cooperat Inst Marine & Atmospher Studies, Miami, FL USA.
11 : Univ Brest, Lab Oceanog Phys & Spatiale, IFREMER, CNRS,IRD,IUEM, Plouzane, France.
12 : Oceans & Coasts Res Branch, Dept Environm Affairs, Cape Town, South Africa.
Source Geophysical Research Letters (0094-8276) (Amer Geophysical Union), 2018-05-01 , Vol. 45 , N. 9 , P. 4180-4188
DOI 10.1029/2018GL077408
WOS© Times Cited 47
Keyword(s) meridional overturning circulation, South Atlantic, overturning, volume transport, observations
Abstract

Six years of simultaneous moored observations near the western and eastern boundaries of the South Atlantic are combined with satellite winds to produce a daily time series of the basin-wide meridional overturning circulation (MOC) volume transport at 34.5 degrees S. The results demonstrate that barotropic and baroclinic signals at both boundaries cause significant transport variations, and as such must be concurrently observed. The data, spanning similar to 20 months during 2009-2010 and similar to 4 years during 2013-2017, reveal a highly energetic MOC record with a temporal standard deviation of 8.3 Sv, and strong variations at time scales ranging from a few days to years (peak-to-peak range = 54.6 Sv). Seasonal transport variations are found to have both semiannual (baroclinic) and annual (Ekman and barotropic) timescales. Interannual MOC variations result from both barotropic and baroclinic changes, with density profile changes at the eastern boundary having the largest impact on the year-to-year variations.

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Meinen Christopher S., Speich Sabrina, Piola Alberto R., Ansorge Isabelle, Campos Edmo, Kersale Marion, Terre Terrillon Thierry, Chidichimo Maria Paz, Lamont Tarron, Sato Olga T., Perez Renellys C., Valla Daniel, Van Den Berg Marcel, Le Henaff Matthieu, Dong Shenfu, Garzoli Silvia L. (2018). Meridional Overturning Circulation Transport Variability at 34.5 degrees S During 2009-2017: Baroclinic and Barotropic Flows and the Dueling Influence of the Boundaries. Geophysical Research Letters, 45(9), 4180-4188. Publisher's official version : https://doi.org/10.1029/2018GL077408 , Open Access version : https://archimer.ifremer.fr/doc/00445/55612/