Articles | Volume 19, issue 3
https://doi.org/10.5194/os-19-535-2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/os-19-535-2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
05 May 2023
Research article |
| 05 May 2023
| 05 May 2023
Joint observation–model mixed-layer heat and salt budgets in the eastern tropical Atlantic
Roy Dorgeless Ngakala
CORRESPONDING AUTHOR
Department of Oceanography and Applications, International Chair in
Mathematical Physics and Applications, University of Abomey-Calavi, Cotonou,
Benin
Department of Oceanography and Environment, Institut National de
Recherche en Sciences Exactes et Naturelles, Pointe-Noire, Congo
Gaël Alory
Laboratoire d'Etudes en Géophysique et Océanographie
Spatiales, University of Toulouse, Toulouse, France
Casimir Yélognissè Da-Allada
Department of Oceanography and Applications, International Chair in
Mathematical Physics and Applications, University of Abomey-Calavi, Cotonou,
Benin
Laboratoire de Géosciences, de l'Environnement et Applications,
Université Nationale des Sciences Technologies, Ingénierie et
Mathématiques, Abomey, Benin
Laboratoire d'Hydrologie Marine et Côtière, Institut de
Recherches Halieutiques et Océanologiques du Bénin, Cotonou, Benin
Olivia Estelle Kom
Department of Oceanography and Applications, International Chair in
Mathematical Physics and Applications, University of Abomey-Calavi, Cotonou,
Benin
Julien Jouanno
Laboratoire d'Etudes en Géophysique et Océanographie
Spatiales, University of Toulouse, Toulouse, France
Willi Rath
GEOMAR Helmholtz-Zentrum für Ozeanforschung Kiel, Kiel, Germany
Ezinvi Baloïtcha
Department of Oceanography and Applications, International Chair in
Mathematical Physics and Applications, University of Abomey-Calavi, Cotonou,
Benin
Related authors
Landry Junior Mbang Essome, Gaël Alory, Casimir Yelognissé Da-allada, Isabelle Dadou, Roy Dorgeless Ngakala, and Guillaume Morvan
EGUsphere, https://doi.org/10.5194/egusphere-2025-5112, https://doi.org/10.5194/egusphere-2025-5112, 2025
This preprint is open for discussion and under review for Ocean Science (OS).
Short summary
Short summary
We used a high-resolution model to study how ocean currents and waves, especially coastal trapped waves, control nitrate variability in the Congolese upwelling system. This nutrient availability drives seasonal marine productivity, with the Congo River also adding significant nitrate. Our research clarifies the complex interplay of physical and biological factors, offering crucial insights for managing regional fisheries and assessing climate change impacts on this vital ecosystem.
Marco Larrañaga, Julien Jouanno, Eric P. Chassignet, Giovanni Durante, Ilkyeong Ma, Julio Sheinbaum, and Lionel Renault
EGUsphere, https://doi.org/10.5194/egusphere-2025-5574, https://doi.org/10.5194/egusphere-2025-5574, 2025
This preprint is open for discussion and under review for Ocean Science (OS).
Short summary
Short summary
We analyze 29 years of satellite altimetry to investigate the detachment of Loop Current Eddies in the Gulf of Mexico. Over half of the Loop Current eddies reattach within a month, while 42 % separate and drift westward. Detachment requires the Loop Current to reach the Mississippi Fan and is strongly influenced by cyclonic eddies, whose configuration determines whether an eddy separates or reattaches to the Loop Current.
Landry Junior Mbang Essome, Gaël Alory, Casimir Yelognissé Da-allada, Isabelle Dadou, Roy Dorgeless Ngakala, and Guillaume Morvan
EGUsphere, https://doi.org/10.5194/egusphere-2025-5112, https://doi.org/10.5194/egusphere-2025-5112, 2025
This preprint is open for discussion and under review for Ocean Science (OS).
Short summary
Short summary
We used a high-resolution model to study how ocean currents and waves, especially coastal trapped waves, control nitrate variability in the Congolese upwelling system. This nutrient availability drives seasonal marine productivity, with the Congo River also adding significant nitrate. Our research clarifies the complex interplay of physical and biological factors, offering crucial insights for managing regional fisheries and assessing climate change impacts on this vital ecosystem.
Marc Kakante Mendy, Florent Gasparin, Manon Gévaudan, Moussa Diakhaté, Issa Sakho, and Julien Jouanno
EGUsphere, https://doi.org/10.5194/egusphere-2025-4429, https://doi.org/10.5194/egusphere-2025-4429, 2025
This preprint is open for discussion and under review for Ocean Science (OS).
Short summary
Short summary
The North Tropical Atlantic plays an important role in shaping climate in the region. In our study we examined how African Easterly Waves influence the ocean surface. Using numerical modelling and buoy records, we found that these waves can warm or cool the sea by more than half a degree. The faster waves have the strongest impact. Because sea temperature affects rainfall and storms, understanding these waves can help improve weather and climate forecasts.
Rosmery Sosa-Gutierrez, Julien Jouanno, and Leo Berline
Ocean Sci., 21, 1505–1514, https://doi.org/10.5194/os-21-1505-2025, https://doi.org/10.5194/os-21-1505-2025, 2025
Short summary
Short summary
Since 2010, pelagic Sargassum spp. blooms have increased in several tropical Atlantic regions, causing socioeconomic and ecosystem impacts. Offshore structuration of Sargassum by mesoscale dynamics may influence transport and growth. Sargassum stays afloat, constantly interacting with currents, waves, winds, and mesoscale eddies. We find that anticyclones and cyclones effectively trap Sargassum throughout its propagation, with a greater tendency for cyclones to accumulate Sargassum.
Yannick Wölker, Willi Rath, Matthias Renz, and Arne Biastoch
EGUsphere, https://doi.org/10.5194/egusphere-2025-2782, https://doi.org/10.5194/egusphere-2025-2782, 2025
Short summary
Short summary
The Atlantic Meridional Overturning Circulation (AMOC) is a large current system that helps regulate Earth's climate. Monitoring the AMOC relies on fixed instruments anchored to the seafloor. This study explores in a high-resolution model whether data from Argo floats, autonomous drifters collecting hydrographic profiles, can be used to monitor the AMOC cost-effectively with the help of Machine Learning. Results suggest that Argo floats can extend AMOC monitoring beyond current fixed arrays.
Gabriela Martinez-Balbontin, Julien Jouanno, Rachid Benshila, Julien Lamouroux, Coralie Perruche, and Stefano Ciavatta
EGUsphere, https://doi.org/10.5194/egusphere-2025-1246, https://doi.org/10.5194/egusphere-2025-1246, 2025
Short summary
Short summary
This study uses machine learning to predict chlorophyll-a levels, which are important for monitoring marine ecosystems and the carbon cycle. By using forecasts of sea surface temperature, salinity, height, and mixed layer depth, we can make global predictions up to six months ahead in just minutes. Our approach is as accurate or better than traditional methods, while being faster and more resource-efficient.
Kristin Burmeister, Franziska U. Schwarzkopf, Willi Rath, Arne Biastoch, Peter Brandt, Joke F. Lübbecke, and Mark Inall
Ocean Sci., 20, 307–339, https://doi.org/10.5194/os-20-307-2024, https://doi.org/10.5194/os-20-307-2024, 2024
Short summary
Short summary
We apply two different forcing products to a high-resolution ocean model to investigate their impact on the simulated upper-current field in the tropical Atlantic. Where possible, we compare the simulated results to long-term observations. We find large discrepancies between the two simulations regarding the wind and current fields. We propose that long-term observations, once they have reached a critical length, need to be used to test the quality of wind-driven simulations.
Peter Brandt, Gaël Alory, Founi Mesmin Awo, Marcus Dengler, Sandrine Djakouré, Rodrigue Anicet Imbol Koungue, Julien Jouanno, Mareike Körner, Marisa Roch, and Mathieu Rouault
Ocean Sci., 19, 581–601, https://doi.org/10.5194/os-19-581-2023, https://doi.org/10.5194/os-19-581-2023, 2023
Short summary
Short summary
Tropical upwelling systems are among the most productive ecosystems globally. The tropical Atlantic upwelling undergoes a strong seasonal cycle that is forced by the wind. Local wind-driven upwelling and remote effects, particularly via the propagation of equatorial and coastal trapped waves, lead to an upward and downward movement of the nitracline. Turbulent mixing results in upward supply of nutrients. Here, we review the different physical processes responsible for biological productivity.
Sarah Berthet, Julien Jouanno, Roland Séférian, Marion Gehlen, and William Llovel
Earth Syst. Dynam., 14, 399–412, https://doi.org/10.5194/esd-14-399-2023, https://doi.org/10.5194/esd-14-399-2023, 2023
Short summary
Short summary
Phytoplankton absorbs the solar radiation entering the ocean surface and contributes to keeping the associated energy in surface waters. This natural effect is either not represented in the ocean component of climate models or its representation is simplified. An incomplete representation of this biophysical interaction affects the way climate models simulate ocean warming, which leads to uncertainties in projections of oceanic emissions of an important greenhouse gas (nitrous oxide).
Michel Tchilibou, Ariane Koch-Larrouy, Simon Barbot, Florent Lyard, Yves Morel, Julien Jouanno, and Rosemary Morrow
Ocean Sci., 18, 1591–1618, https://doi.org/10.5194/os-18-1591-2022, https://doi.org/10.5194/os-18-1591-2022, 2022
Short summary
Short summary
This high-resolution model-based study investigates the variability in the generation, propagation, and sea height signature (SSH) of the internal tide off the Amazon shelf during two contrasted seasons. ITs propagate further north during the season characterized by weak currents and mesoscale eddies and a shallow and strong pycnocline. IT imprints on SSH dominate those of the geostrophic motion for horizontal scales below 200 km; moreover, the SSH is mainly incoherent below 70 km.
Alan D. Fox, Patricia Handmann, Christina Schmidt, Neil Fraser, Siren Rühs, Alejandra Sanchez-Franks, Torge Martin, Marilena Oltmanns, Clare Johnson, Willi Rath, N. Penny Holliday, Arne Biastoch, Stuart A. Cunningham, and Igor Yashayaev
Ocean Sci., 18, 1507–1533, https://doi.org/10.5194/os-18-1507-2022, https://doi.org/10.5194/os-18-1507-2022, 2022
Short summary
Short summary
Observations of the eastern subpolar North Atlantic in the 2010s show exceptional freshening and cooling of the upper ocean, peaking in 2016 with the lowest salinities recorded for 120 years. Using results from a high-resolution ocean model, supported by observations, we propose that the leading cause is reduced surface cooling over the preceding decade in the Labrador Sea, leading to increased outflow of less dense water and so to freshening and cooling of the eastern subpolar North Atlantic.
Pierre Damien, Julio Sheinbaum, Orens Pasqueron de Fommervault, Julien Jouanno, Lorena Linacre, and Olaf Duteil
Biogeosciences, 18, 4281–4303, https://doi.org/10.5194/bg-18-4281-2021, https://doi.org/10.5194/bg-18-4281-2021, 2021
Short summary
Short summary
The Gulf of Mexico deep waters are relatively poor in phytoplankton biomass due to low levels of nutrients in the upper layers. Using modeling techniques, we find that the long-living anticyclonic Loop Current eddies that are shed episodically from the Yucatan Channel strongly shape the distribution of phytoplankton and, more importantly, stimulate their growth. This results from the contribution of multiple mechanisms of physical–biogeochemical interactions discussed in this study.
Julien Jouanno, Rachid Benshila, Léo Berline, Antonin Soulié, Marie-Hélène Radenac, Guillaume Morvan, Frédéric Diaz, Julio Sheinbaum, Cristele Chevalier, Thierry Thibaut, Thomas Changeux, Frédéric Menard, Sarah Berthet, Olivier Aumont, Christian Ethé, Pierre Nabat, and Marc Mallet
Geosci. Model Dev., 14, 4069–4086, https://doi.org/10.5194/gmd-14-4069-2021, https://doi.org/10.5194/gmd-14-4069-2021, 2021
Short summary
Short summary
The tropical Atlantic has been facing a massive proliferation of Sargassum since 2011, with severe environmental and socioeconomic impacts. We developed a modeling framework based on the NEMO ocean model, which integrates transport by currents and waves, and physiology of Sargassum with varying internal nutrient quota, and considers stranding at the coast. Results demonstrate the ability of the model to reproduce and forecast the seasonal cycle and large-scale distribution of Sargassum biomass.
Cited articles
Aguedjou, H. M. A., Dadou, I., Chaigneau, A., Morel, Y., and Alory, G.:
Eddies in the Tropical Atlantic Ocean and Their Seasonal Variability,
Geophys. Res. Lett., 46, 12156–12164, https://doi.org/10.1029/2019GL083925,
2019.
Alory, G., Da-Allada, C. Y., Djakouré, S., Dadou, I., Jouanno, J., and
Loemba, D. P.: Coastal Upwelling Limitation by Onshore Geostrophic Flow in
the Gulf of Guinea Around the Niger River Plume, Front. Mar. Sci., 7,
https://doi.org/10.3389/fmars.2020.607216, 2021.
Awo, F. M., Alory, G., Da-Allada, C. Y., Delcroix, T., Jouanno, J.,
Kestenare, E., and Baloïtcha, E.: Sea Surface Salinity Signature of the
Tropical Atlantic Interannual Climatic Modes, J. Geophys. Res.-Oceans, 123,
7420–7437, https://doi.org/10.1029/2018JC013837, 2018.
Awo, F. M., Rouault, M., Ostrowski, M., Tomety, F. S., Da-Allada, C. Y., and
Jouanno, J.: Seasonal Cycle of Sea Surface Salinity in the Angola Upwelling
System, J. Geophys. Res.-Oceans, 127, 1–13,
https://doi.org/10.1029/2022JC018518, 2022.
Berger, H., Treguier, A. M., Perenne, N., and Talandier, C.: Dynamical
contribution to sea surface salinity variations in the eastern Gulf of
Guinea based on numerical modelling, Clim. Dynam., 43, 3105–3122,
https://doi.org/10.1007/s00382-014-2195-4, 2014.
Bingham, F. M., Foltz, G. R., and McPhaden, M. J.: Characteristics of the seasonal cycle of surface layer salinity in the global ocean, Ocean Sci., 8, 915–929, https://doi.org/10.5194/os-8-915-2012, 2012.
Bonjean, F. and Lagerloef, G. S. E.: Diagnostic model and analysis of the
surface currents in the Tropical Pacific Ocean, J. Phys. Oceanogr., 32,
2938–2954, https://doi.org/10.1175/1520-0485(2002)032<2938:DMAAOT>2.0.CO;2, 2002.
Bourlès, B., Araujo, M., McPhaden, M. J., Brandt, P., Foltz, G. R.,
Lumpkin, R., Giordani, H., Hernandez, F., Lefèvre, N., Nobre, P.,
Campos, E., Saravanan, R., Trotte-Duhà, J., Dengler, M., Hahn, J.,
Hummels, R., Lübbecke, J. F., Rouault, M., Cotrim, L., Sutton, A.,
Jochum, M., and Perez, R. C.: PIRATA: A Sustained Observing System for
Tropical Atlantic Climate Research and Forecasting, Earth Sp. Sci., 6,
577–616, https://doi.org/10.1029/2018EA000428, 2019.
Boutin, J., Chao, Y., Asher, W. E., Delcroix, T., Drucker, R., Drushka, K.,
Kolodziejczyk, N., Lee, T., Reul, N., Reverdin, G., Schanze, J., Soloviev,
A., Yu, L., Anderson, J., Brucker, L., Dinnat, E., Santos-Garcia, A., Jones,
W. L., Maes, C., Meissner, T., Tang, W., Vinogradova, N., and Ward, B.:
Satellite and in situ salinity understanding near-surface stratification and
subfootprint variability, B. Am. Meteorol. Soc., 97, 1391–1407,
https://doi.org/10.1175/BAMS-D-15-00032.1, 2016.
Camara, I., Kolodziejczyk, N., Mignot, J., Lazar, A., and Gaye, A. T.: On
the seasonal variations of salinity of the tropical Atlantic mixed layer, J.
Geophys. Res.-Oceans, 120, 4441–4462,
https://doi.org/10.1002/2015JC010865, 2015.
Caniaux, G., Giordani, H., Redelsperger, J. L., Guichard, F., Key, E., and
Wade, M.: Coupling between the Atlantic cold tongue and the West African
monsoon in boreal spring and summer, J. Geophys. Res.-Oceans, 116, 1–17,
https://doi.org/10.1029/2010JC006570, 2011.
Carton, J. A. and Zhou, Z.: Annual cycle of sea surface temperature in the
tropical Atlantic Ocean, J. Geophys. Res.-Oceans, 102, 27813–27824,
https://doi.org/10.1029/97JC02197, 1997.
Chang, P., Yamagata, T., Schopf, P., Behera, S. K., Carton, J., Kessler, W.
S., Meyers, G., Qu, T., Schott, F., Shetye, S., and Xie, S. P.: Climate
fluctuations of tropical coupled systems – The role of ocean dynamics, J.
Climate, 19, 5122–5174, https://doi.org/10.1175/JCLI3903.1, 2006.
Chavez, F. P. and Messié, M.: A comparison of Eastern Boundary Upwelling
Ecosystems, Prog. Oceanogr., 83, 80–96,
https://doi.org/10.1016/j.pocean.2009.07.032, 2009.
Chelton, D. B., Deszoeke, R. A., Schlax, M. G., El Naggar, K., and Siwertz,
N.: Geographical variability of the first baroclinic Rossby radius of
deformation, J. Phys. Oceanogr., 28, 433–460,
https://doi.org/10.1175/1520-0485(1998)028<0433:GVOTFB>2.0.CO;2, 1998.
Da-Allada, C. Y., Alory, G., Du Penhoat, Y., Kestenare, E., Durand, F., and
Hounkonnou, N. M.: Seasonal mixed-layer salinity balance in the tropical
Atlantic Ocean: Mean state and seasonal cycle, J. Geophys. Res.-Oceans, 118,
332–345, https://doi.org/10.1029/2012JC008357, 2013.
Da-Allada, C. Y., du Penhoat, Y., Jouanno, J., Alory, G., and Hounkonnou, N.
M.: Modeled mixed-layer salinity balance in the Gulf of Guinea: seasonal and
interannual variability, Ocean Dynam., 64, 1783–1802,
https://doi.org/10.1007/s10236-014-0775-9, 2014.
Da-Allada, C. Y., Jouanno, J., Gaillard, F., Kolodziejczyk, N., Maes, C.,
Reul, N., and Bourlès, B.: Importance of the Equatorial Undercurrent on
the sea surface salinity in the eastern equatorial Atlantic in boreal
spring, J. Geophys. Res.-Oceans, 122, 521–538,
https://doi.org/10.1002/2016JC012342, 2017.
Dai, A. and Trenberth, K. E.: Estimates of Freshwater Discharge from
Continents: Latitudinal and Seasonal Variations, J. Hydrometeorol., 3,
660–687, https://doi.org/10.1175/1525-7541(2002)003<0660:EOFDFC>2.0.CO;2, 2002.
de Boyer Montégut, C., Madec, G., Fischer, A. S., Lazar, A., and
Iudicone, D.: Mixed layer depth over the global ocean: An examination of
profile data and a profile-based climatology, J. Geophys. Res.-Oceans, 109,
1–20, https://doi.org/10.1029/2004JC002378, 2004.
Delcroix, T. and Henin, C.: Seasonal and interannual variations of sea
surface salinity in the tropical Pacific Ocean, J. Geophys. Res.-Oceans, 96,
22135–22150, https://doi.org/10.1029/91JC02124, 1991.
Dengler, M. and Rath, W.: Seasonal heat and fresh water mixed-layer balance
climatology, 1–15, 2015.
Djakouré, S., Penven, P., Bourlès, B., Veitch, J., and Koné, V.:
Coastally trapped eddies in the north of the Gulf of Guinea, J. Geophys.
Res.-Oceans, 119, 6805–6819,
https://doi.org/10.1002/2014JC010243, 2014.
Djakouré, S., Penven, P., Bourlès, B., Koné, V., and Veitch, J.:
Respective roles of the Guinea current and local winds on the coastal
upwelling in the northern Gulf of Guinea, J. Phys. Oceanogr., 47,
1367–1387, https://doi.org/10.1175/JPO-D-16-0126.1, 2017.
Durack, P. J. and Wijffels, S. E.: Fifty-Year trends in global ocean
salinities and their relationship to broad-scale warming, J. Climate, 23,
4342–4362, https://doi.org/10.1175/2010JCLI3377.1, 2010.
Dussin, R., Barnier, B., Brodeau, L., and Molines, J. M.: The making of the
DRAKKAR Forcing Set DFS5, Drakkar, MyOcean Report, Grenoble, 2016 pp., http://www.drakkar-ocean.eu/publications/reports/report_DFS5v3_April2016.pdf (last access: 27 April 2023), 2016.
Farrar, J. T. and Plueddemann, A. J.: On the Factors Driving Upper-Ocean
Salinity Variability at the Western Edge of the Eastern Pacific Fresh Pool.,
Oceanography (Wash. D. C)., 32, 30–39,
https://doi.org/10.5670/oceanog.2019.209, 2019.
Farrar, J. T., Rainville, L., Plueddemann, A. J., Kessler, W. S., Lee, C.,
Hodges, B. A., Schmitt, R. W., Edson, J. B., Riser, S. C., and Eriksen, C.
C.: Salinity and temperature balances at the SPURS central mooring during
fall and winter, Oceanography, 28, 56–65, 2015.
Foltz, G. R. and McPhaden, M. J.: Seasonal mixed layer salinity balance of
the tropical North Atlantic Ocean, J. Geophys. Res.-Oceans, 113, 1–14,
https://doi.org/10.1029/2007JC004178, 2008.
Foltz, G. R., Grodsky, S. A., Carton, J. A., and McPhaden, M. J.: Seasonal mixed layer heat budget of the tropical Atlantic Ocean, J. Geophys. Res.-Oceans, 108, 148–227, https://doi.org/10.1029/2002JC001584, 2003.
Foltz, G. R., Grodsky, S. A., Carton, J. A., and McPhaden, M. J.: Seasonal
salt budget of the northwestern tropical Atlantic Ocean along 38∘ W, J. Geophys. Res.-Oceans, 109, 1–13,
https://doi.org/10.1029/2003jc002111, 2004.
Foltz, G. R., Schmid, C., and Lumpkin, R.: Seasonal cycle of the mixed layer
heat budget in the northeastern tropical atlantic ocean, J. Climate, 26,
8169–8188, https://doi.org/10.1175/JCLI-D-13-00037.1, 2013.
Gordon, A. L. and Bosley, K. T.: Cyclonic gyre in the tropical South
Atlantic, Deep Sea Res., 38, 323–343,
https://doi.org/10.1016/s0198-0149(12)80015-x, 1991.
Grodsky, S. A., Carton, J. A., Provost, C., Servain, J., Lorenzzetti, J. A.,
and Mcphaden, M. J.: 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.-Oceans, 110, 1–12,
https://doi.org/10.1029/2005JC002941, 2005.
Hagen, E., Feistel, R., Agenbag, J. J., and Ohde, T.: Seasonal and
interannual changes in intense Benguela upwelling (1982–1999), Oceanol.
Acta, 24, 557–568, https://doi.org/10.1016/S0399-1784(01)01173-2, 2001.
Hasson, A. E. A., Delcroix, T., and Dussin, R.: An assessment of the mixed
layer salinity budget in the tropical Pacific Ocean. Observations and
modelling (1990–2009), Ocean Dynam., 63, 179–194,
https://doi.org/10.1007/s10236-013-0596-2, 2013.
Hernandez, O., Jouanno, J., and Durand, F.: Do the Amazon and Orinoco
freshwater plumes really matter for hurricane-induced ocean surface
cooling?, J. Geophys. Res.-Oceans, 121, 2119–2141,
https://doi.org/10.1002/2015JC011021, 2016.
Heukamp, F. O., Brandt, P., Dengler, M., Tuchen, F. P., McPhaden, M. J., and
Moum, J. N.: Tropical Instability Waves and Wind-Forced Cross-Equatorial
Flow in the Central Atlantic Ocean, Geophys. Res. Lett., 49, e2022GL099325, https://doi.org/10.1029/2022GL099325,
2022.
Holte, J. and Talley, L.: A new algorithm for finding mixed layer depths
with applications to argo data and subantarctic mode water formation, J.
Atmos. Ocean. Technol., 26, 1920–1939,
https://doi.org/10.1175/2009JTECHO543.1, 2009.
Houndegnonto, O. J., Kolodziejczyk, N., Maes, C., Bourlès, B.,
Da-Allada, C. Y., and Reul, N.: Seasonal Variability of Freshwater Plumes in
the Eastern Gulf of Guinea as Inferred From Satellite Measurements, J.
Geophys. Res.-Oceans, 126, 1–57, https://doi.org/10.1029/2020JC017041,
2021.
Huffman, G. J., Adler, R. F., Bolvin, D. T., and Gu, G.: Improving the
global precipitation record: GPCP Version 2.1, Geophys. Res. Lett., 36,
1–5, https://doi.org/10.1029/2009GL040000, 2009.
Hummels, R., Dengler, M., and Bourlès, B.: Seasonal and regional
variability of upper ocean diapycnal heat flux in the Atlantic cold tongue,
Prog. Oceanogr., 111, 52–74, https://doi.org/10.1016/j.pocean.2012.11.001,
2013.
Hummels, R., Dengler, M., Brandt, P., and Schlundt, M.: Diapycnal heat flux
and mixed layer heat budget within the Atlantic Cold Tongue, Clim. Dynam., 43,
3179–3199, https://doi.org/10.1007/s00382-014-2339-6, 2014.
Jochum, M., Malanotte-Rizzoli, P., and Busalacchi, A.: Tropical instability
waves in the Atlantic Ocean, Ocean Model., 7, 145–163,
https://doi.org/10.1016/S1463-5003(03)00042-8, 2004.
Jochum, M., Murtugudde, R., Ferrari, R., and Malanotte-Rizzoli, P.: The
Impact of Horizontal Resolution on the Tropical Heat Budget in an Atlantic
Ocean Model, J. Climate, 18, 841–851, https://doi.org/10.1175/JCLI-3288.1,
2005.
Jouanno, J., Marin, F., Du Penhoat, Y., Sheinbaum, J., and Molines, J. M.:
Seasonal heat balance in the upper 100 m of the equatorial Atlantic Ocean,
J. Geophys. Res.-Oceans, 116, 1–19, https://doi.org/10.1029/2010JC006912,
2011.
Jouanno, J., Hernandez, O., and Sanchez-Gomez, E.: Equatorial Atlantic interannual variability and its relation to dynamic and thermodynamic processes, Earth Syst. Dynam., 8, 1061–1069, https://doi.org/10.5194/esd-8-1061-2017, 2017.
Junker, T., Schmidt, M., and Mohrholz, V.: The relation of wind stress curl
and meridional transport in the Benguela upwelling system, J. Mar. Syst.,
143, 1–6, https://doi.org/10.1016/j.jmarsys.2014.10.006, 2015.
Junker, T., Mohrholz, V., Siegfried, L., and van der Plas, A.: Seasonal to
interannual variability of water mass characteristics and currents on the
Namibian shelf, J. Mar. Syst., 165, 36–46,
https://doi.org/10.1016/j.jmarsys.2016.09.003, 2017.
Kopte, R., Brandt, P., Dengler, M., Tchipalanga, P. C. M., Macuéria, M.,
and Ostrowski, M.: The Angola Current: Flow and hydrographic characteristics
as observed at 11∘ S, J. Geophys. Res.-Oceans, 122, 1177–1189,
https://doi.org/10.1002/2016JC012374, 2017.
Kumar, B. P., Vialard, J., Lengaigne, M., Murty, V. S. N., and McPhaden, M.
J.: TropFlux: air-sea fluxes for the global tropical oceans – description
and evaluation, Clim. Dynam., 38, 1521–1543,
https://doi.org/10.1007/s00382-011-1115-0, 2012.
Kushnir, Y., Robinson, W. A., Chang, P., and Robertson, A. W.: The physical
basis for predicting Atlantic sector seasonal-to-interannual climate
variability, J. Climate, 19, 5949–5970, https://doi.org/10.1175/JCLI3943.1,
2006.
Large, W. G. and Yeager, S. G.: The global climatology of an interannually
varying air – Sea flux data set, Clim. Dynam., 33, 341–364,
https://doi.org/10.1007/s00382-008-0441-3, 2009.
Lebedev, K. V, Yoshinari, H., Maximenko, N. A., and Hacker, P. W.: Velocity
data derived from trajectories of Argo floats, IPRC Tech. Note, 2, 20 pp., 2007.
Lee, T., Lagerloef, G., Kao, H., McPhaden, M. J., Willis, J., and Gierach,
M. M.: The influence of salinity on tropical Atlantic instability waves, J.
Geophys. Res.-Oceans, 119, 8375–8394, https://doi.org/10.1002/2014JC010100,
2014.
Lumpkin, R., Grodsky, S. A., Centurioni, L., Rio, M. H., Carton, J. A., and
Lee, D.: Removing spurious low-frequency variability in drifter velocities,
J. Atmos. Ocean. Technol., 30, 353–360,
https://doi.org/10.1175/JTECH-D-12-00139.1, 2013.
Morrow, R., Fu, L. L., Ardhuin, F., Benkiran, M., Chapron, B., Cosme, E.,
D'Ovidio, F., Farrar, J. T., Gille, S. T., Lapeyre, G., Le Traon, P. Y.,
Pascual, A., Ponte, A., Qiu, B., Rascle, N., Ubelmann, C., Wang, J., and
Zaron, E.: Global observations of fine-scale ocean surface topography with
the Surface Water and Ocean Topography (SWOT) Mission, Front. Mar. Sci., 6,
1–19, https://doi.org/10.3389/fmars.2019.00232, 2019.
Muller, A. A., Reason, C. J. C., Schmidt, M., Mohrholz, V., and Eggert, A.:
Computing transport budgets along the shelf and across the shelf edge in the
northern Benguela during summer (DJF) and winter (JJA), J. Mar. Syst., 140,
82–91, https://doi.org/10.1016/j.jmarsys.2014.02.007, 2014.
Ndoye, S., Capet, X., Estrade, P., Sow, B., Dagorne, D., Lazar, A., Gaye,
A., and Brehmer, P.: SST patterns and dynamics of the southern
Senegal-Gambia upwelling center, J. Geophys. Res.-Oceans, 119, 8315–8335,
https://doi.org/10.1002/2014JC010242, 2014.
Ostrowski, M., Da Silva, J. C. B., and Bazik-Sangolay, B.: The response of
sound scatterers to El Ninõ- and La Niña-like oceanographic regimes
in the southeastern Atlantic, ICES J. Mar. Sci., 66, 1063–1072,
https://doi.org/10.1093/icesjms/fsp102, 2009.
Peter, A. C., Le Hénaff, M., du Penhoat, Y., Menkes, C. E., Marin, F.,
Vialard, J., Caniaux, G., and Lazar, A.: A model study of the seasonal mixed
layer heat budget in the equatorial Atlantic, J. Geophys. Res.-Oceans, 111,
1–16, https://doi.org/10.1029/2005JC003157, 2006.
Philander, S. G. H. and Pacanowski, R. C.: The oceanic response to
cross-equatorial winds (with application to coastal upwelling in low
latitudes), Tellus, 33, 201–210,
https://doi.org/10.3402/tellusa.v33i2.10708, 1981.
Picaut, J.: Propagation of the Seasonal Upwelling in the Eastern Equatorial
Atlantic, https://doi.org/10.1175/1520-0485(1983)013<0018:potsui>2.0.co;2, 1983.
Rath, W., Dengler, M., Lüdke, J., Schmidtko, S., Schlundt, M., Brandt,
P., Bumke, K., Ostrowski, M., van der Plas, A., Junker, T., Mohrholz, V.,
Sarre, A., Tchipalanga, P. C. M., and Coelho, P.: PREFCLIM: A
high-resolution mixed-layer climatology of the eastern tropical Atlantic, PANGAEA [data set],
https://doi.org/10.1594/PANGAEA.868927, 2016.
Reason, C. J. C. and Rouault, M.: Sea surface temperature variability in the
tropical southeast Atlantic Ocean and West African rainfall, Geophys. Res.
Lett., 33, 1–5, https://doi.org/10.1029/2006GL027145, 2006.
Rodriguez-Fernandez, N. J., Anterrieu, E., Boutin, J., Supply, A., Reverdin,
G., Alory, G., Remy, E., Picard, G., Pellarin, T., and Richaume, P.: The
SMOS-HR Mission: Science Case and Project Status, in: IGARSS 2022–2022, IEEE T. Geosci. Remote, 7182–7185, 2022.
Scannell, H. A. and McPhaden, M. J.: Seasonal Mixed Layer Temperature
Balance in the Southeastern Tropical Atlantic, J. Geophys. Res.-Oceans, 123,
5557–5570, https://doi.org/10.1029/2018JC014099, 2018.
Schlundt, M., Brandt, P., Dengler, M., Hummels, R., Fischer, T., Bumke, K.,
Krahmann, G., and Karstensen, J.: Mixed layer heat and salinity budgets
during the onset of the 2011 Atlantic cold tongue, J. Geophys. Res.-Oceans,
119, 7882–7910, https://doi.org/10.1002/2014JC010021, 2014.
Schmidtko, S., Johnson, G. C., and Lyman, J. M.: MIMOC: A global monthly
isopycnal upper-ocean climatology with mixed layers, J. Geophys. Res.-Oceans, 118, 1658–1672, https://doi.org/10.1002/jgrc.20122,
2013.
Stevenson, J. W. and Niiler, P. P.: Upper Ocean Heat Budget During the
Hawaii-to-Tahiti Shuttle Experiment, J. Phys. Oceanogr., 13, 1894–1907,
https://doi.org/10.1175/1520-0485(1983)013<1894:UOHBDT>2.0.CO;2, 1983.
Taylor, K. E.: Summarizing multiple aspects of model performance in a single
diagram, J. Geophys. Res.-Atmos., 106, 7183–7192,
https://doi.org/10.1029/2000JD900719, 2001.
Tuchen, F. P., Perez, R. C., Foltz, G. R., Brandt, P., and Lumpkin, R.:
Multidecadal Intensification of Atlantic Tropical Instability Waves,
Geophys. Res. Lett., 49, 1–11, https://doi.org/10.1029/2022gl101073, 2022.
Tzortzi, E., Josey, S. A., Srokosz, M., and Gommenginger, C.: Tropical
atlantic salinity variability: New insights from SMOS, Geophys. Res. Lett.,
40, 2143–2147, https://doi.org/10.1002/grl.50225, 2013.
Vijith, V., Vinayachandran, P. N., Webber, B. G. M., Matthews, A. J.,
George, J. V., Kannaujia, V. K., Lotliker, A. A., and Amol, P.: Closing the
sea surface mixed layer temperature budget from in situ observations alone:
Operation Advection during BoBBLE, Sci. Rep., 10, 1–12,
https://doi.org/10.1038/s41598-020-63320-0, 2020.
Wade, M., Caniaux, G., and Du Penhoat, Y.: Variability of the mixed layer
heat budget in the eastern equatorial Atlantic during 2005–2007 as inferred
using Argo floats, J. Geophys. Res.-Oceans, 116, 1–17,
https://doi.org/10.1029/2010JC006683, 2011.
Waliser, D. E. and Gautier, C.: A satellite-derived climatology of the ITCZ,
https://doi.org/10.1175/1520-0442(1993)006<2162:ASDCOT>2.0.CO;2, 1993.
Yu, L., Jin, X., and Weller, R. A.: Role of net surface heat flux in
seasonal variations of sea surface temperature in the tropical Atlantic
Ocean, J. Climate, 19, 6153–6169, https://doi.org/10.1175/JCLI3970.1, 2006.
Short summary
Surface heat flux is the main driver of the heat budget in the Senegal, Angola, and Benguela regions but not in the equatorial region. In the Senegal and Benguela regions, freshwater flux governs the salt budget, while in equatorial and Angola regions, oceanic processes are the main drivers. Results from numerical simulation show the important role of mesoscale advection for temperature and salinity variations in the mixed layer. Nonlinear processes unresolved by observations play a key role.
Surface heat flux is the main driver of the heat budget in the Senegal, Angola, and Benguela...
