Climate Dynamics

, Volume 43, Issue 11, pp 2943–2962 | Cite as

Mean meridional currents in the central and eastern equatorial Atlantic

  • Renellys C. Perez
  • Verena Hormann
  • Rick Lumpkin
  • Peter Brandt
  • William E. Johns
  • Fabrice Hernandez
  • Claudia Schmid
  • Bernard Bourlès
Article

Abstract

Ship-based acoustic Doppler current profiler (ADCP) velocity measurements collected by several major field programs in the tropical Atlantic are averaged and combined with estimates of the mean near-surface velocity derived from drifters and Argo float surface drifts (ADCP+D) to describe the mean cross-equatorial and vertical structure of the meridional currents along 23°W and 10°W. Data from moored ADCPs and fixed-depth current meters, a satellite-derived velocity product, and a global ocean reanalysis were additionally used to evaluate the mean ADCP+D meridional velocity. The dominant circulation features in the long-term mean ADCP+D meridional velocity in the upper 100 m are the tropical cells (TCs) located approximately between 5°S and 5°N, with near-surface poleward flow and subsurface equatorward flow that is stronger and shallower in the northern cell compared to the southern cell. The thickness of the surface limb of the TCs decreases and the northern cell is found to shift further south of the equator from the central to eastern tropical Atlantic. Analysis of two-season means estimated from the ship-based ADCP, near-surface drift, and moored velocity data, as well as the simulated fields, indicates that the maximum poleward velocity in the surface limb of the TCs intensifies during December–May along 23°W largely due to seasonal compensation between the geostrophic and ageostrophic (or wind-driven) components of the meridional velocity, whereas the maximum equatorward flow in the subsurface limb of the northern cell intensifies during June–November along both 23°W and 10°W due to the seasonality of the geostrophic meridional velocity.

Keywords

Tropical Atlantic Meridional currents Tropical cells 

References

  1. Athié G, Marin F (2008) Cross-equatorial structure and temporal modulation of intraseasonal variability at the surface of the tropical Atlantic Ocean. J Geophys Res 113:C08020. doi:10.1029/2007JC004332 Google Scholar
  2. Athié G, Marin F, Treguier A-M, Bourlès B, Guiavarc’h C (2009) Sensitivity of near-surface tropical instability waves to submonthly wind forcing in the tropical Atlantic. Ocean Model 30:241–255. doi:10.1016/j.ocemod.2009.06.016 CrossRefGoogle Scholar
  3. Barnier B, Madec G, Penduff T, Molines J-M, Treguier A-M, Le Sommer J, Beckmann A, Biastoch A, Böning C, Dengg J, Derval C, Durand E, Gulev S, Remy E, Talandier C, Theetten S, Maltrud M, McClean J, De Cuevas B (2006) Impact of partial steps and momentum advection schemes in a global ocean circulation model at eddy-permitting resolution. Ocean Dyn 56:543–567. doi:10.1007/s10236-006-0082-1 CrossRefGoogle Scholar
  4. Benkiran M, Greiner E (2008) Impact of the incremental analysis updates on a real-time system of the North Atlantic Ocean. J Atmos Ocean Technol 25:2055–2073CrossRefGoogle Scholar
  5. Bloom SC, Takas LL, Da Silva AM, Ledvina D (1996) Data assimilation using incremental analysis updates. Mon Weather Rev 124:1256–1271CrossRefGoogle Scholar
  6. Bonjean F, Lagerloef GSE (2002) Diagnostic model and analysis of the surface currents in the tropical Pacific Ocean. J Phys Oceanogr 32:2938–2954CrossRefGoogle Scholar
  7. Bourlès B, Lumpkin R, McPhaden MJ, Hernandez F, Nobre P, Campos E, Yu L, Planton S, Busalacchi A, Moura AD, Servain J, Trotte J (2008) The PIRATA program: history, accomplishments, and future directions. Bull Am Meteorol Soc 89:1111–1125. doi:10.1175/2008BAMS2462.1 CrossRefGoogle Scholar
  8. Brandt P, Schott FA, Provost C, Kartavtseff A, Hormann V, Bourlès B, Fischer J (2006) Circulation in the central equatorial Atlantic: mean and intraseasonal to seasonal variability. Geophys Res Lett 33:L07609. doi:10.1029/2005GL025498 CrossRefGoogle Scholar
  9. Brandt P, Hormann V, Bourlès B, Fischer J, Schott FA, Stramma L, Dengler M (2008) Oxygen tongues and zonal currents in the equatorial Atlantic. J Geophys Res 113:C04012. doi:10.1029/2007JC004435 Google Scholar
  10. Brandt P, Hormann V, Körtzinger A, Visbeck M, Krahmann G, Stramma L, Lumpkin R, Schmid C (2010) Changes in the ventilation of the oxygen minimum zone of the tropical North Atlantic. J Phys Oceanogr 40:1784–1801. doi:10.1175/2010JPO4301.1 CrossRefGoogle Scholar
  11. Brandt P, Caniaux G, Bourlès B, Lazar A, Dengler M, Funk A, Hormann V, Giordani H, Marin F (2011a) Equatorial upper-ocean dynamics and their interaction with the West African monsoon. Atmos Sci Lett 12:24–30. doi:10.1002/asl.287 CrossRefGoogle Scholar
  12. Brandt P, Funk A, Hormann V, Dengler M, Greatbatch RJ, Toole JM (2011b) Interannual atmospheric variability forced by the deep equatorial Atlantic Ocean. Nature 43:497–500. doi:10.1038/nature10013 CrossRefGoogle Scholar
  13. Brandt P, Funk A, Tantet A, Johns W, Fischer J (2013) The Equatorial Undercurrent in the central Atlantic and its relation to tropical Atlantic variability. Clim Dyn, submittedGoogle Scholar
  14. Bunge L, Provost C, Kartavtseff A (2007) Variability in horizontal current velocities in the central and eastern equatorial Atlantic in 2002. J Geophys Res 112:C02014. doi:10.1029/2006JC003704 Google Scholar
  15. Chang P, Yamagata T, Schopf P, Behera SK, Carton J, Kessler WS, Meyers G, Qu T, Schott F, Shetye S, Xie SP (2006) Climate fluctuations of tropical coupled systems—the role of ocean dynamics. J Clim 19:5122–5174. doi:10.1175/JCLI3903.1 CrossRefGoogle Scholar
  16. Da-Allada CY, Alory G, du Penhoat Y, Kestenare E, Durand F, Hounkonnou NM (2013) Seasonal mixed-layer salinity balance in the tropical Atlantic Ocean: mean state and seasonal cycle. J Geophys Res 118:332–345. doi:10.1029/2012JC008357 CrossRefGoogle Scholar
  17. Düing W, Hisard P, Katz E, Meincke J, Miller L, Moroshkin KV, Philander G, Ribnikov AA, Voigt K, Weisberg R (1975) Meanders and long waves in the equatorial Atlantic. Nature 257:280–284. doi:10.1038/257280a0 CrossRefGoogle Scholar
  18. Dutrieux P, Menkes CE, Vialard J, Flament P, Blanke B (2008) Lagrangian study of tropical instability vortices in the Atlantic. J Phys Oceanogr 38:400–417. doi:10.1175/2007JPO3763.1 CrossRefGoogle Scholar
  19. Ferry N, Parent L, Garric G, Barnier B, Jourdain NC, MERCATOR Group (2010) Mercator global Eddy permitting ocean reanalysis GLORYS1V1: description and results. Mercator Ocean Q Newsl 36:15–27Google Scholar
  20. Fischer J, Brandt P, Dengler M, Müller M, Symonds D (2003) Surveying the upper ocean with the Ocean Surveyor: a new phased array Doppler current profiler. J Atmos Ocean Technol 20:742–751CrossRefGoogle Scholar
  21. Foltz GR, Carton JA, Chassignet EP (2004) Tropical instability vortices in the Atlantic Ocean. J Geophys Res 109:C03029. doi:10.1029/2003JC001942 Google Scholar
  22. Foltz GR, McPhaden MJ, Lumpkin R (2012) A strong Atlantic meridional mode event in 2009: the role of mixed layer dynamics. J Clim 25:363–380. doi:10.1175/JCLI-D-11-00150.1 CrossRefGoogle Scholar
  23. Freitag HP, McPhaden MJ, Meinig C, Plimpton P (2003) Mooring motion bias of point Doppler current meter measurements. In: Proceedings of the IEEE seventh working conference on current measurement technology, San Diego, CA, 13–15 Mar 2003, IEEE, Piscataway, NJ, pp 155–160Google Scholar
  24. Garzoli SL (1987) Forced oscillations on the equatorial Atlantic Basin during the seasonal response of the Equatorial Atlantic Program (1983–1984). J Geophys Res 5089(C5):5089–5100. doi:10.1029/JC092iC05p05089 CrossRefGoogle Scholar
  25. Giordani H, Caniaux G (2011) Diagnosing vertical motion in the equatorial Atlantic. Ocean Dyn 61:1995–2018. doi:10.1007/s10236-011-0467-7 CrossRefGoogle Scholar
  26. Goldenberg SB, Landsea C, Mestas-Nunez AM, Gray WM (2001) The recent increase in Atlantic hurricane activity. Science 293:474–479CrossRefGoogle Scholar
  27. Grodsky SA, Carton JA, Provost C, Servain J, Lorenzzetti JA, McPhaden MJ (2005) Tropical instability waves at 0 N, 23 W in the Atlantic: a case study using Pilot Research Moored Array in the Tropical Atlantic (PIRATA) mooring data. J Geophys Res 110:C08010. doi:10.1029/2005JC002941 Google Scholar
  28. Hazeleger W, de Vries P, Friocourt Y (2003) Sources of the Equatorial Undercurrent in the Atlantic in a high-resolution ocean model. J Phys Oceanogr 33:677–693CrossRefGoogle Scholar
  29. Helber RW, Weisberg RH, Bonjean F, Johnson ES, Lagerloef GSE (2007) Satellite-derived surface current divergence in relation to tropical Atlantic SST and wind. J Phys Oceanogr 33:1357–1375CrossRefGoogle Scholar
  30. Hormann V, Brandt P (2007) Atlantic Equatorial Undercurrent and associated cold tongue variability. J Geophys Res 112:C06017. doi:10.1029/2006JC003931 Google Scholar
  31. Hormann V, Brandt P (2009) Upper equatorial Atlantic variability during 2002 and 2005 associated with equatorial Kelvin waves. J Geophys Res 114:C03007. doi:10.1029/2008JC005101 Google Scholar
  32. Hormann V, Lumpkin R, Perez RC (2013) A generalized method for estimating the structure of the equatorial Atlantic cold tongue: application to drifter observations. J Atmos Ocean Technol 30:1884–1895. doi:10.1175/JTECH-D-12-00173.1 CrossRefGoogle Scholar
  33. Hummels R, Dengler M, Bourlès B (2013) Seasonal and regional variability of upper ocean diapycnal heat flux in the Atlantic cold tongue. Prog Oceanogr 111:52–74. doi:10.1016/j.pocean.2012.11.001 CrossRefGoogle Scholar
  34. Johnson G, McPhaden MJ, Firing E (2001) Equatorial Pacific Ocean horizontal velocity, divergence, and upwelling. J Phys Oceanogr 31:839–849CrossRefGoogle Scholar
  35. Johnson G, Sloyan BM, Kessler WS, McTaggart KE (2002) Direct measurements of upper ocean currents and water properties across the tropical Pacific Ocean during the 1990s. Prog Oceanogr 52:31–61CrossRefGoogle Scholar
  36. Jouanno J, Marin F, du Penhoat Y, Molines J-M (2013) Intraseasonal modulation of the surface cooling in the Gulf of Guinea. J Phys Oceanogr 43:382–401. doi:10.1175/JPO-D-12-053.1 CrossRefGoogle Scholar
  37. Kolodziejczyk N, Bourlès B, Marin F, Grelet J, Chuchla R (2009) Seasonal variability of the Equatorial Undercurrent at 10 W as inferred from recent in situ observations. J Geophys Res 114:C06014. doi:10.1029/2008JC004976 Google Scholar
  38. Kushnir Y, Robinson WA, Chang P, Robertson AW (2006) The physical basis for predicting Atlantic sector seasonal-to-interannual climate variability. J Clim 19:5949–5970CrossRefGoogle Scholar
  39. Lebedev KV, Yoshinari H, Maximenko NA, Hacker PW (2007) Velocity data assessed from trajectories of Argo floats at parking level and at the sea surface. IPRC Technical Note, No. 4(2), 12 June 2007, p 16Google Scholar
  40. Legeckis R (1977) Long waves in the eastern equatorial Pacific Ocean: a view from a geostationary satellite. Science 197:1179–1181CrossRefGoogle Scholar
  41. Legeckis R, Reverdin G (1987) Long waves in the equatorial Atlantic Ocean during 1983. J Geophys Res 92:2835–2842CrossRefGoogle Scholar
  42. Liu Z, Philander SGH, Pacanowski RC (1994) A GCM study of tropical–subtropical upper-ocean water exchange. J Phys Oceanogr 24:2606–2623CrossRefGoogle Scholar
  43. Lohmann K, Latif M (2007) Influence of El Niño on the upper-ocean circulation in the tropical Atlantic Ocean. J Clim 20:5012–5018. doi:10.1175/JCLI4292.1 CrossRefGoogle Scholar
  44. Lübbecke JF (2013) Tropical Atlantic warm events. Nat Geosci 6:22–23. doi:10.1038/ngeo1685 CrossRefGoogle Scholar
  45. Lumpkin R, Garraffo Z (2005) Evaluating the decomposition of tropical Atlantic drifter observations. J Atmos Ocean Technol 22:1403–1415CrossRefGoogle Scholar
  46. Lumpkin R, Garzoli SL (2005) Near-surface circulation in the tropical Atlantic Ocean. Deep Sea Res I 52:495–518. doi:10.1016/j.dsr.2004.09.001 CrossRefGoogle Scholar
  47. Lumpkin R, Grodsky S, Rio M-H, Centurioni L, Carton J, Lee D (2013) Removing spurious low-frequency variability in surface drifter velocities. J Atmos Ocean Technol 30(2):353–360. doi:10.1175/JTECH-D-12-00139.1 CrossRefGoogle Scholar
  48. Madec G (2008) NEMO ocean engine. Note du pole de modélisation, Institut Pierre-Simon Laplace (IPSL), France, No 27, ISSN No 1288-1619, p 201Google Scholar
  49. Malanotte-Rizzoli P, Hedstrom K, Arango H, Haidvogel DB (2000) Water mass pathways between the subtropical and tropical ocean in a climatological simulation of the North Atlantic ocean circulation. Dyn Atmos Ocean 32:331–371CrossRefGoogle Scholar
  50. McCreary JP, Lu P (1994) Interaction between the subtropical and equatorial ocean circulations: the subtropical cell. J Phys Oceanogr 24:466–497CrossRefGoogle Scholar
  51. Menkes CE, Flament P, Dandonneau Y, Masson S, Biessy B, Marchal E, Eldin G, Grelet J, Montel Y, Morlière A, Lebourges-Dhaussy A, Moulin C, Champalbert G, Herbland A (2002) A whirling ecosystem in the equatorial Atlantic. Geophys Res Lett 29:1553. doi:10.1029/2001GL014576 CrossRefGoogle Scholar
  52. Molinari RL, Bauer S, Snowden D, Johnson GC, Bourlès B, Gouriou Y, Mercier H (2003) A comparison of kinematic evidence for tropical cells in the Atlantic and Pacific oceans. In: Goni GJ, Malanotte-Rizzoli P (eds) IAPSO special issue: interhemispheric water exchange in the Atlantic Ocean, Elsevier Oceanography Series 68:269–286Google Scholar
  53. Niiler PP, Paduan JD (1995) Wind-driven motions in the northeast Pacific as measured by Lagrangian drifters. J Phys Oceanogr 25:2819–2830CrossRefGoogle Scholar
  54. Okumura Y, Xie S-P (2004) Interaction of the Atlantic equatorial cold tongue and the African monsoon. J Clim 17:3589–3602CrossRefGoogle Scholar
  55. Pazan SE, Niiler PP (2001) Recovery of near-surface velocity from undrogued drifters. J Atmos Ocean Technol 18:476–489CrossRefGoogle Scholar
  56. Perez RC, Kessler WS (2009) The three-dimensional structure of tropical cells in the central equatorial Pacific Ocean. J Phys Oceanogr 39:27–49. doi:10.1175/2008JPO4029.1 CrossRefGoogle Scholar
  57. Perez RC, Cronin MF, Kessler WS (2010) Tropical cells and a secondary circulation near the northern front of the equatorial Pacific cold tongue. J Phys Oceanogr 40:2091–2106. doi:10.1175/2010JPO4366.1 CrossRefGoogle Scholar
  58. Perez RC, Lumpkin R, Johns WE, Foltz GR, Hormann V (2012) Interannual variations of Atlantic tropical instability waves. J Geophys Res 117:C03011. doi:10.1029/2011JC007584 Google Scholar
  59. Pham DT, Verron J, Roubaud M-C (1998) A singular evolutive extended Kalman filter for data assimilation in oceanography. J Mar Syst 16:323–340CrossRefGoogle Scholar
  60. Philander SGH, Pacanowksi RC (1986) A model of the seasonal cycle in the tropical Atlantic Ocean. J Geophys Res 91(C12):14192–14206CrossRefGoogle Scholar
  61. Plimpton PE, Freitag HP, McPhaden MJ (2004) Processing of subsurface ADCP data in the equatorial Pacific. NOAA Tech. Memo OAR PMEL-125, NOAA/Pacific Marine Environmental Laboratory, Seattle, WA, p 41Google Scholar
  62. Provost C, Arnault S, Chouaib N, Kartavtseff A, Bunge L, Sultan E (2004) TOPEX/Poseidon and Jason equatorial sea surface slope anomaly in the Atlantic in 2002: comparison with wind and current measurements at 23 W. Mar Geod 27:31–45CrossRefGoogle Scholar
  63. Qiao L, Weisberg RH (1995) Tropical instability wave kinematics: observations from the Tropical Instability Wave Experiment (TIWE). J Phys Oceanogr 100:8677–8693Google Scholar
  64. Rabe B, Schott FA, Köhl A (2008) Mean circulation and variability of the tropical Atlantic during 1952–2001 in the GECCO assimilation fields. J Phys Oceanogr 38:177–192CrossRefGoogle Scholar
  65. Richter I, Behera SK, Masumoto Y, Taguchi B, Sasaki H, Yamagata T (2013) Multiple causes of interannual sea surface temperature variability in the equatorial Atlantic Ocean. Nat Geosci 6:43–47. doi:10.1038/ngeo1660 Google Scholar
  66. Schott FA, Dengler M, Brandt P, Affler K, Fischer J, Bourlès B, Gouriou Y, Molinari RL, Rhein M (2003) The zonal currents and transports at 35 W in the tropical Atlantic. Geophys Res Lett 30(7):1349. doi:10.1029/2002GL016849 CrossRefGoogle Scholar
  67. Schott F, McCreary J, Johnson G (2004) Shallow overturning circulations of the tropical-subtropical oceans. In: Wang C, Xie S-P, Carton JA (eds) Earth climate: the ocean–atmosphere interaction, AGU Geophysical Monograph Series 147:261–304Google Scholar
  68. Seo H, Xie S-P (2011) Response and impact of equatorial ocean dynamics and tropical instability waves in the tropical Atlantic under global warming: a regional coupled downscaling study. J Geophys Res 116:C03026. doi:10.1029/2010JC006670 Google Scholar
  69. Seo H, Jochum M, Murtugudde R, Miller AJ, Roads JO (2007) Feedback of tropical instability-wave-induced atmospheric variability onto the ocean. J Clim 20:5842–5855. doi:10.1175/2007JCLI1700.1 CrossRefGoogle Scholar
  70. Simmons A, Uppala S, Dee D, Kobayashi S (2007) ERAInterim: new ECMWF reanalysis products from 1989 onwards. ECMWF Newsl 110:25–35Google Scholar
  71. Steger JM, Carton JA (1991) Long waves and eddies in the tropical Atlantic Ocean: 1984–1990. J Geophys Res 96:15161–15171CrossRefGoogle Scholar
  72. Subramaniam A, Mahaffey C, Johns W, Mahowald N (2013) Equatorial upwelling enhances nitrogen fixation in the Atlantic Ocean. Geophys Res Lett 40:1766–1771. doi:10.1002/grl.50250 Google Scholar
  73. Sutton RT, Hodson DLR (2005) Atlantic Ocean forcing of North American and European summer climate. Science 309:115–118. doi:10.1175/JCLI4038.1 CrossRefGoogle Scholar
  74. Tokinaga H, Xie S-P (2011) Weakening of the equatorial Atlantic cold tongue over the past six decades. Nature Geosci 4:222–226. doi:10.1038/ngeo1078 CrossRefGoogle Scholar
  75. Tranchant B, Testut C-E, Renault L, Ferry N, Birol F, Brasseur P (2008) Expected impact of the future SMOS and Aquarius Ocean surface salinity missions in the Mercator Ocean operational systems: new perspectives to monitor ocean circulation. Remote Sens Environ 112:1476–1487CrossRefGoogle Scholar
  76. Visbeck M (2002) Deep velocity profiling using lowered acoustic Doppler current profilers: bottomtrack and inverse solutions. J Atmos Ocean Technol 19:794–807CrossRefGoogle Scholar
  77. von Schuckmann K, Brandt P, Eden C (2008) Generation of tropical instability waves in the Atlantic Ocean. J Geophys Res 113:C08034. doi:10.1029/2007JC004712 Google Scholar
  78. Weisberg RH, Weingartner TJ (1988) Instability waves in the equatorial Atlantic Ocean. J Phys Oceanogr 18:1641–1657CrossRefGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  • Renellys C. Perez
    • 1
    • 2
  • Verena Hormann
    • 3
  • Rick Lumpkin
    • 2
  • Peter Brandt
    • 4
  • William E. Johns
    • 5
  • Fabrice Hernandez
    • 6
  • Claudia Schmid
    • 2
  • Bernard Bourlès
    • 7
  1. 1.Cooperative Institute for Marine and Atmospheric StudiesUniversity of MiamiMiamiUSA
  2. 2.NOAA Atlantic Oceanographic and Meteorological LaboratoryMiamiUSA
  3. 3.Scripps Institution of OceanographyUniversity of California, San DiegoLa JollaUSA
  4. 4.GEOMAR Helmholtz-Zentrum für Ozeanforschung KielKielGermany
  5. 5.Rosenstiel School of Marine and Atmospheric ScienceUniversity of MiamiMiamiUSA
  6. 6.Institut de Recherche pour le Développement, Mercator-OcéanToulouseFrance
  7. 7.Institut de Recherche pour le Développement, LEGOSBrestFrance

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