Influence of intraseasonal eastern boundary circulation variability on hydrography and biogeochemistry off Peru.

Lüdke, Jan , Dengler, Marcus , Sommer, Stefan, Clemens, David , Thomsen, Sören , Krahmann, Gerd , Dale, Andrew W. , Achterberg, Eric P. and Visbeck, Martin (2019) Influence of intraseasonal eastern boundary circulation variability on hydrography and biogeochemistry off Peru. Open Access Ocean Science Discussions . DOI 10.5194/os-2019-93.

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Abstract

The Peruvian Upwelling System is characterized by high primary productivity fuelled by the supply of nutrients in a highly dynamic boundary circulation. The intraseasonal evolution of the physical and biogeochemical properties is analysed based on shipboard observations and remote sensing conducted between April and June 2017 off central Peru. The poleward transport in the subsurface Peru Chile Undercurrent was highly variable and strongly intensified between mid and end of May. This intensification was likely caused by a first baroclinic mode downwelling coastal trapped wave excited at the equator at about 95° W that propagated poleward along the South American coast. The intensified poleward flow shortens the time of water mass advection from the equatorial current system to the study site. The impact of the anomalous advection is mostly noticed in the nitrogen cycle because during the shorter time needed for poleward advection less fixed nitrogen loss occurs within the waters. This causes a strong increase of nitrate concentrations and a decrease in the nitrogen deficit. These changes suggest that the advection caused by the coastal trapped wave supersedes the simultaneous effect of anomalous downwelling in terms of nutrient response.

Document Type: Article
Research affiliation: OceanRep > SFB 754
OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-MG Marine Geosystems
OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-CH Chemical Oceanography
OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-PO Physical Oceanography
Refereed: No
Open Access Journal?: Yes
DOI etc.: 10.5194/os-2019-93
ISSN: 1812-0822
Projects: SFB754
Expeditions/Models/Experiments:
Date Deposited: 05 Aug 2019 08:04
Last Modified: 23 Sep 2019 19:39
URI: http://oceanrep.geomar.de/id/eprint/47344

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