Investigating of the two-core structure of the Atlantic North Equatorial Countercurrent with the GLORYS12V1 reanalysis
DOI:
https://doi.org/10.5914/tropocean.v49i1.252688Palavras-chave:
Tropical Atlantic, North Equatorial Countercurrent, Two-core structure, volume transport, wind stress curl, GLORYS12V1 reanalysis.Resumo
Twenty-six years of the high-resolution global ocean reanalysis GLORYS12V1 are used to investigate the temporal and spatial variability of the two-core structure of the North Equatorial Counter Current (NECC) in the western and central tropical Atlantic. The two cores of the NECC exhibit mean positions of 6.3°N±1.4° and 9.7°N±1°, and of 5.4°N±1.1° and 8.9°N±0.9° respectively in the area west of 32°W and in the area between 32°W and 22°W. Both areas witness a semi-annual cycle of the position of the southern core with northernmost positions respectively in May and July, and in March and July. The transport of the branch associated to the southern cores shows annual cycles with maxima occurring in August (>17 Sv) and July (>7 Sv) respectively in the western and central areas. The annual cycle in the West is influenced by the wind stress curl (WSC) strength. The central area might be influenced by a return flow of the northern branch of the South Equatorial Current over the central Atlantic. At the opposite, the transport associated with the NECC’s northern core shows the same annual cycles with maxima occurring in September in both areas. This transport of the NECC shows seasonal cycles leaded by the WSC strength with 1-month lag. 83% and 71% of the total transport between the first 150 m-depth is above the thermocline respectively in the western and central areas. In the West, the northern core transport shows year-to-year variations associated with the WSC strength, while the southern core position of the NECC in the central tropical Atlantic appears influenced by the InterTropical Convergence Zone migration.
Referências
Artana, C., Lellouche, J.-M., Sennéchael, N. and Provost, C. (2018), The Open-Ocean Side of the Malvinas Current in Argo Floats and 24 Years of Mercator Ocean High-Resolution (1/12) Physical Reanalysis, Journal of Geophysical Research: Oceans, Vol. 123, n. 11 , pp. 8489–8507, doi:10.1029/2018jc014528.
Artana, C., Provost, C., Lellouche, J. M., Rio, M. H., Ferrari, R., and Sennéchael, N. (2019). The Malvinas current at the confluence with the Brazil current: Inferences from 25 years of Mercator ocean reanalysis. Journal of Geophysical Research: Oceans, 124(10), 7178-7200, doi:10.1029/2019jc015289.
Burmeister K., Lübbecke, J. F.,Brandt, P. and Duteil, O. (2019), Interannual variability of the Atlantic North Equatorial Undercurrent and its impact on oxygen, Journal of Geophysical Research: Oceans, Vol. 124, pp. 2348–2373, doi: 10.1029/2018JC014760.
Cabanes, C., Grouazel, A., von Schuckmann, K., Hamon, M., Turpin, V., Coatanoan, C. et al.(2013), The CORA dataset: validation and diagnostics of in-situ ocean temperature and salinity measurements, Ocean Science, Vol. 9, n. 1, pp. 1-18, doi: 10.5194/os-9-1-2013.
Castellanos, P., Pelegrí, J.L., Campos, E.J.D., Rosell-Fieschi, M. and Gasser, M. (2015), Response of the surface tropical Atlantic Ocean to wind forcing, Progress in Oceanography, pp. 134271-292, doi: 10.1016/j.pocean.2015.02.005.
Didden, N. and Schott, F. (1992), Seasonal variations in the western tropical Atlantic: Surface circulation from Geosat altimetry and WOCE model results, Journal of Geophysical Research: Oceans, Vol. 97, n. C3, pp. 3529-3541, doi: 10.1029/91jc02860.
Fonseca, C. A., Goni, G. J., Johns, W. E., and Campos, E. J. (2004). Investigation of the north Brazil current retroflection and north equatorial countercurrent variability. Geophysical Re-search Letters, 31(21), doi:10.1029/2004gl020054.
Garzoli, S.L. and Katz, E.J. (1983), The Forced Annual Reversal of the Atlantic North Equatorial Countercurrent, Journal of Physical Oceanography, Vol. 13, n. 11, pp. 2082-2090, doi: 10.1175/1520-0485(1983)013<2082:Tfarot>2.0.Co;2.
Garzoli, S.L. andRichardson, P.L. (1989), Low-frequency meandering of the Atlantic North Equatorial Countercurrent, Journal of Geophysical Research: Oceans, Vol. 94, n. C2, pp. 2079-2090, doi: 10.1029/JC094iC02p02079.
Garzoli, S.L. (1992), The Atlantic North Equatorial Countercurrent: Models and observations, Journal of Geophysical Research: Oceans, Vol. 97, n. C11, pp. 17931-17946, doi: 10.1029/92jc01363.
Góes, M., and Wainer, I. (2003). Equatorial currents transport changes for extreme warm and cold events in the Atlantic Ocean. Geophysical research letters, Vol. 30, n.5,doi: 10.1029/2002GL015707.
Good, S.A., Martin, M.J. andRayner, N.A. (2013), EN4: Quality controlled ocean temperature and salinity profiles and monthly objective analyses with uncertainty estimates, Journal of Geophysical Research: Oceans, Vol. 118, n. 12, pp. 6704-6716, doi: 10.1002/2013jc009067.
Hormann, V., Lumpkin, R., and Foltz, G. R. (2012). Interannual North Equatorial Countercurrent variability and its relation to tropical Atlantic climate modes. Journal of Geophysical Research: Oceans, Vol. 117, n. C4,doi: 10.1029/2011jc007697.
Lellouche, J.-M., Greiner, E., Le Galloudec, O., Garric, G., Regnier, C., Drevillon, M. et al.(2018), Recent updates to the Copernicus Marine Service Global ocean monitoring and forecasting real-time 1∕12° high-resolution system, Ocean Science, Vol. 14, n. 5, pp. 1093-1126, doi: 10.5194/os-14-1093-2018.
Jean-Michel, L., Eric, G., Romain, B. B., Gilles, G., Angélique, M., Marie, D. et al.(2021). The Copernicus global 1/12° oceanic and sea ice GLORYS12 reanalysis. Frontiers in Earth Science, Vol. 9, pp. 585, doi: 10.3389/feart.2021.698876.
Madec, G. (2008), NEMO ocean engine -Version 3.1, Note du Pôle de modélisation, (27), edited by Institut Pierre-Simon Laplace (IPSL), Paris, France, 201 p.
Philander, S.G.H. and Pacanowski, R.C. (1986), The mass and heat budget in a model of the tropical Atlantic Ocean, Journal of Geophysical Research: Oceans, Vol. 91, n. C12, pp. 14212-14220, doi: 10.1029/JC091iC12p14212.
Poli, L., Artana, C., Provost, C., Sirven, J., Sennéchael, N., Cuypers, Y. et al.(2020). Anatomy of subinertial waves along the Patagonian shelf break in a 1/12° global operational model. Journal of Geophysical Research: Oceans, 125(12), doi:10.1029/2020jc016549.
Polonsky, A.B. and Artamonov, Y.V. (1997), North Equatorial Counter-current in the tropical Atlantic: Multi-jet structure and seasonal variability, Ocean Dynamics, Vol. 49, pp. 477–495, doi: 10.1007/bf02764342.
Richardson, P.L. and McKee, T.K. (1984), Average seasonal variation of the Atlantic equatorial currents from historical ship-drifts, Journal of Physical Oceanography, Vol. 14, pp. 1226–1238, doi: 10.1175/1520-0485(1984)014<1226:ASVOTA>2.0.CO;2.
Richardson,P.L. andReverdin, G. (1987), Seasonal cycle of velocity in the Atlantic North Equatorial Countercurrent as measured by surface drifters, current meters, and ship drifts, Journal of Geophysical Research: Oceans, Vol. 92, n. C4, pp. 3691-3708, doi: 10.1029/JC092iC04p03691.
Rosell-Fieschi, M., Pelegrí, J.L. and Gourrion, J. (2015), Zonal jets in the equatorial Atlantic Ocean, Progress in Oceanography,Vol. 130, pp. 1–18, doi: 10.1007/bf02764342.
Schott, F.A. and Böning C.W. (1991), The WOCE model in the western equatorial Atlantic: Upper layer circulation, Journal of Geophysical Research: Oceans, Vol. 96, n. C4, pp. 6993-7004, doi: 10.1029/90jc02683.
Schott, F.A., McCreary, J.P. and Johnson, G.C. (2004), Shallow overturning circulations of the tropical–subtropical oceans, In: Wang, C., Carton, J. and Xie, S.-P. (Eds.), Ocean–Atmosphere Interaction and Climate Variability,AGU, Washington, pp. 261–304.
Urbano, D.F., Jochum, M. and da Silveira, I.C.A. (2006), Rediscovering the second core of the Atlantic NECC,Ocean Modelling, Vol. 12, n. 1, pp. 1-15, doi: 10.1016/j.ocemod.2005.04.003.
Urbano, D. F., De Almeida, R. A. F., and Nobre, P. (2008). Equatorial Undercurrent and North Equatorial Countercurrent at 38 W: A new perspective from direct velocity data. Journal of Geophysical Research: Oceans, 113(C4), doi: 10.1029/2007jc004215.
Varona, H.L., Veleda, D., Silva, M., Cintra, M. and Araujo, M. (2019), Amazon River plume influence on Western Tropical Atlantic dynamic variability, Dynamics of Atmospheres and Oceans, Vol. 85, pp. 1-15, doi: 10.1016/j.dynatmoce.2018.10.002.
Verdy, A. and Jochum, M. (2005), A note on the validity of the Sverdrup balance in the Atlantic North Equatorial Countercurrent, Deep Sea Research Part I: Oceanographic Research Papers, Vol. 52, n. 1, pp. 179-188, doi: 10.1016/j.dsr.2004.05.014.
Xie, S. and Carton, J. (2004), Tropical Atlantic variability: Patterns, mechanisms, andimpacts, Geophysical Monograph Series, Vol. 147, pp. 121–142, doi: 10.1029/147GM07.
Yang, J. and Joyce, T.M. (2006), Local and equatorial forcing of seasonal variations of the North Equatorial Countercurrent in the Atlantic Ocean, Journal of Physical Oceanography, Vol. 36, pp. 238–254, doi: 10.1175/JPO2848.1.