English
 
Privacy Policy Disclaimer
  Advanced SearchBrowse

Item

ITEM ACTIONSEXPORT
Add to Basket
  Local TagsRelease HistoryDetailsSummary

Released
Conference Paper

Seasonal cycle of mixing and upward nutrient supply in the equatorial Atlantic cold tongue

Authors

Brandt,  Peter
IUGG 2023, General Assemblies, 1 General, International Union of Geodesy and Geophysics (IUGG), External Organizations;

Körner,  Mareike
IUGG 2023, General Assemblies, 1 General, International Union of Geodesy and Geophysics (IUGG), External Organizations;

Moum,  James N.
IUGG 2023, General Assemblies, 1 General, International Union of Geodesy and Geophysics (IUGG), External Organizations;

Subramaniam,  Ajit
IUGG 2023, General Assemblies, 1 General, International Union of Geodesy and Geophysics (IUGG), External Organizations;

Czeschel,  Rena
IUGG 2023, General Assemblies, 1 General, International Union of Geodesy and Geophysics (IUGG), External Organizations;

Krahmann,  Gerd
IUGG 2023, General Assemblies, 1 General, International Union of Geodesy and Geophysics (IUGG), External Organizations;

Dengler,  Marcus
IUGG 2023, General Assemblies, 1 General, International Union of Geodesy and Geophysics (IUGG), External Organizations;

Roch,  Marisa
IUGG 2023, General Assemblies, 1 General, International Union of Geodesy and Geophysics (IUGG), External Organizations;

Kiko,  Rainer
IUGG 2023, General Assemblies, 1 General, International Union of Geodesy and Geophysics (IUGG), External Organizations;

External Ressource
No external resources are shared
Fulltext (public)
There are no public fulltexts stored in GFZpublic
Supplementary Material (public)
There is no public supplementary material available
Citation

Brandt, P., Körner, M., Moum, J. N., Subramaniam, A., Czeschel, R., Krahmann, G., Dengler, M., Roch, M., Kiko, R. (2023): Seasonal cycle of mixing and upward nutrient supply in the equatorial Atlantic cold tongue, XXVIII General Assembly of the International Union of Geodesy and Geophysics (IUGG) (Berlin 2023).
https://doi.org/10.57757/IUGG23-1033


Cite as: https://gfzpublic.gfz-potsdam.de/pubman/item/item_5018234
Abstract
The eastern equatorial Atlantic hosts a productive marine ecosystem that depends on the upward supply of nutrients. The main process that transports nutrients into the surface mixed layer is turbulent mixing induced in the shear zone between the surface mixed layer and the core of the Equatorial Undercurrent (EUC). Here we present experimental data from two trans-Atlantic cruises along the equator as well as moored observations allowing to characterize the seasonal cycle of velocity shear and turbulence. These data in combination with hydrographic data allow the analysis of the seasonal cycle of equatorial mixing and upward nitrate flux. The core of the EUC migrates vertically following an annual cycle. It reaches its shallowest position in boreal spring and its deepest position in boreal fall. The seasonal cycle of the maximum nitrate gradient instead shows a primary upward movement during boreal summer and a secondary upward movement in boreal winter bringing the nitrate gradient into the region of enhanced shear and turbulent mixing. During boreal spring, the nitrate gradient is located below the EUC core that is characterized by a minimum of turbulence. It prevents an upward supply of nitrate into the surface mixed layer and results in low productivity. The dynamic behavior of the shear zone is driven by a resonant equatorial basin mode associated with the east- and westward propagation of equatorial Kelvin and Rossby waves making the seasonal cycle of upward nutrient supply and productivity in the equatorial Atlantic distinct from that in the Pacific Ocean.