Powered by OpenAIRE graph
Found an issue? Give us feedback
image/svg+xml art designer at PLoS, modified by Wikipedia users Nina, Beao, JakobVoss, and AnonMoos Open Access logo, converted into svg, designed by PLoS. This version with transparent background. http://commons.wikimedia.org/wiki/File:Open_Access_logo_PLoS_white.svg art designer at PLoS, modified by Wikipedia users Nina, Beao, JakobVoss, and AnonMoos http://www.plos.org/ Biogeosciences (BG)arrow_drop_down
image/svg+xml art designer at PLoS, modified by Wikipedia users Nina, Beao, JakobVoss, and AnonMoos Open Access logo, converted into svg, designed by PLoS. This version with transparent background. http://commons.wikimedia.org/wiki/File:Open_Access_logo_PLoS_white.svg art designer at PLoS, modified by Wikipedia users Nina, Beao, JakobVoss, and AnonMoos http://www.plos.org/

Coupled physical/biogeochemical modeling including O2-dependent processes in the Eastern Boundary Upwelling Systems: application in the Benguela

Authors: Gutknecht, E.; Dadou, I.; Vu, B.; Cambon, G.; Sudre, J.; Garçon, V.; Machu, E.; +5 Authors

Coupled physical/biogeochemical modeling including O2-dependent processes in the Eastern Boundary Upwelling Systems: application in the Benguela

Abstract

The Eastern Boundary Upwelling Systems (EBUS) contribute to one fifth of the global catches in the ocean. Often associated with Oxygen Minimum Zones (OMZs), EBUS represent key regions for the oceanic nitrogen (N) cycle. Important bioavailable N loss due to denitrification and anammox processes as well as greenhouse gas emissions (e.g, N2O) occur also in these EBUS. However, their dynamics are currently crudely represented in global models. In the climate change context, improving our capability to properly represent these areas is crucial due to anticipated changes in the winds, productivity, and oxygen content. We developed a biogeochemical model (BioEBUS) taking into account the main processes linked with EBUS and associated OMZs. We implemented this model in a 3-D realistic coupled physical/biogeochemical configuration in the Namibian upwelling system (northern Benguela) using the high-resolution hydrodynamic ROMS model. We present here a validation using in situ and satellite data as well as diagnostic metrics and sensitivity analyses of key parameters and N2O parameterizations. The impact of parameter values on the OMZ off Namibia, on N loss, and on N2O concentrations and emissions is detailed. The model realistically reproduces the vertical distribution and seasonal cycle of observed oxygen, nitrate, and chlorophyll a concentrations, and the rates of microbial processes (e.g, NH4+ and NO2− oxidation, NO3− reduction, and anammox) as well. Based on our sensitivity analyses, biogeochemical parameter values associated with organic matter decomposition, vertical sinking, and nitrification play a key role for the low-oxygen water content, N loss, and N2O concentrations in the OMZ. Moreover, the explicit parameterization of both steps of nitrification, ammonium oxidation to nitrate with nitrite as an explicit intermediate, is necessary to improve the representation of microbial activity linked with the OMZ. The simulated minimum oxygen concentrations are driven by the poleward meridional advection of oxygen-depleted waters offshore of a 300 m isobath and by the biogeochemical activity inshore of this isobath, highlighting a spatial shift of dominant processes maintaining the minimum oxygen concentrations off Namibia. In the OMZ off Namibia, the magnitude of N2O outgassing and of N loss is comparable. Anammox contributes to about 20% of total N loss, an estimate lower than currently assumed (up to 50%) for the global ocean.

121 references, page 1 of 13

Aiken, J. and Bale, A. J.: An introduction to the Atlantic Meridional Transect (AMT) Programme, Prog. Oceanogr., 45, 251- 256, doi:10.1016/S0079-6611(00)00004-5, 2000.

Aiken, J., Woodward, M. S., Robinson, C., Rees, A., Serret, P., Bowie, A., Woodd-Walker, R., Pilgrim, D., Holligan, P., Suggett, D., Hooker, S., Dempsey, C., Brown, J., Maritorena, S., Barlow, R., Lucas, M., and Tilstone, G.: Atlantic Meridional Transect, AMT 6 cruise report, 14 May 5 to 16 June 1998, Plymouth Marine Laboratory, Plymouth, UK, 147 pp., 1998.

Aiken, J., Rees, N., Hooker, S., Holligan, P., Bale, A., Robins, D., Moore, G., Harris, R., and Pilgrim, D.: The Atlantic Meridional Transect: overview and synthesis of data, Prog. Oceanogr., 45, 257-312, doi:10.1016/S0079-6611(00)00005-7, 2000.

Anderson, J. J., Okubo, A., Robbins, A. S., and Richards, F. A.: A model for nitrite and nitrate distributions in oceanic oxygen minimum zones, Deep-Sea Res., 29, 1113-1140, 1982.

Anonymous: Greenhouse gases hit modern day-highs, Nature, 456, 558-559, doi:10.1038/456558b, 2008.

Arrigo, R. A.: Marine microorganisms and global nutrient cycles, Nature, 437, 349-355, 2005.

Bakun, A., Field, D. B., Redondo-Rodriguez, A., and Scarla, J.: Greenhouse gas, upwelling-favorable winds, and the future of coastal ocean ,upwelling ecosystems, Glob. Change Biol., 16, 1213-1228, doi:10.1111/j.1365-2486.2009.02094.x, 2010.

Banyte, D., Tanhua, T., Visbeck, M., Wallace, D. W. R., Karstensen, J., Krahmann, G., Schneider, A., Stramma, L., and Dengler, M., Diapycnal diffusivity at the upper boundary of the tropical North Atlantic oxygen minimum zone, J. Geophys. Res., 117, C09016, doi:10.1029/2011JC007762, 2012. [OpenAIRE]

Barlow, R. G., Aiken, J., Holligan, P. M., Cummings, D. G., Maritorena, S., and Hooker, S.: Phytoplankton pigment and absorption characteristics along meridional transects in the Atlantic Ocean, Deep Sea Res. Pt I, 49, 637-660, doi:10.1016/S0967- 0637(01)00081-4, 2002.

Barlow, R. G., Aiken, J., Moore, G. F., Holligan, P. M., and Lavender, S.: Pigment adaptations in surface phytoplankton along the eastern boundary of the Atlantic Ocean, Mar. Ecol. Prog.-Ser., 281, 13-26, doi:10.3354/meps281013, 2004.

  • BIP!
    Impact byBIP!
    citations
    This is an alternative to the "Influence" indicator, which also reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
    0
    popularity
    This indicator reflects the "current" impact/attention (the "hype") of an article in the research community at large, based on the underlying citation network.
    Average
    influence
    This indicator reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
    Average
    impulse
    This indicator reflects the initial momentum of an article directly after its publication, based on the underlying citation network.
    Average
  • citations
    This is an alternative to the "Influence" indicator, which also reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
    0
    popularity
    This indicator reflects the "current" impact/attention (the "hype") of an article in the research community at large, based on the underlying citation network.
    Average
    influence
    This indicator reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
    Average
    impulse
    This indicator reflects the initial momentum of an article directly after its publication, based on the underlying citation network.
    Average
    Powered byBIP!BIP!
Powered by OpenAIRE graph
Found an issue? Give us feedback
citations
This is an alternative to the "Influence" indicator, which also reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Citations provided by BIP!
popularity
This indicator reflects the "current" impact/attention (the "hype") of an article in the research community at large, based on the underlying citation network.
BIP!Popularity provided by BIP!
influence
This indicator reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Influence provided by BIP!
impulse
This indicator reflects the initial momentum of an article directly after its publication, based on the underlying citation network.
BIP!Impulse provided by BIP!
0
Average
Average
Average
Funded by
EC| MEECE
Project
MEECE
Marine Ecosystem Evolution in a Changing Environment
  • Funder: European Commission (EC)
  • Project Code: 212085
  • Funding stream: FP7 | SP1 | ENV
Related to Research communities
Sustainable Development Solutions Network - Greece
moresidebar

Do the share buttons not appear? Please make sure, any blocking addon is disabled, and then reload the page.