References

Biogeosciences

1726-4189

Copernicus Publications

Göttingen, Germany

10.5194/bg-9-4099-2012

Mass, nutrient and oxygen budgets for the northeastern Atlantic Ocean

Maze

¹ Mercier

² Thierry

¹ Memery

³ Morin

⁴ Perez

F. F.

⁵

Ifremer, Laboratoire de Physique des Océans, UMR6523, CNRS, Ifremer, IRD, UBO, Plouzané, France

CNRS, Laboratoire de Physique des Océans, UMR6523, CNRS, Ifremer, IRD, UBO, Plouzané, France

CNRS, Laboratoire des sciences de l'Environnement Marin, UMR6539, CNRS, IRD, UBO, Plouzané, France

CNRS, Chimie Marine, UMR7144, AD2M, CNRS & Université Pierre et Marie Curie Paris VI, Place Georges Teissier, 29682 Roscoff, France

Instituto de Investigaciones Marinas (CSIC), Vigo, Spain

24 10 2012

9 10 4099 4113

2012

This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/

This article is available from https://bg.copernicus.org/articles/9/4099/2012/bg-9-4099-2012.html

The full text article is available as a PDF file from https://bg.copernicus.org/articles/9/4099/2012/bg-9-4099-2012.pdf

The northeast Atlantic is a key horizontal and vertical crossroads region for the meridional overturning circulation, but basic nutrient and oxygen fluxes are still poorly constrained by observations in the region. A surface to bottom northeast Atlantic Ocean budget for mass, nutrients (nitrate and phosphate) and oxygen is determined using an optimization method based on three surveys of the OVIDE transect (from Greenland to Portugal) completed with the World Ocean Atlas 2009. Budgets are derived for two communicating boxes representing the northeastern European basin (NEEB) and the Irminger Sea. For the NEEB (Irminger) box, it is found that 30% of the mass import (export) across the OVIDE section reach (originate from) the Nordic Seas, while 70% are redistributed between both boxes through the Reykjanes Ridge (9.3 ± 0.7 × 109 kg s−1). Net biological source/sink terms of nitrate point to both the Irminger and NEEB boxes as net organic matter production sites (consuming nitrate at a rate of –7.8 ± 6.5 kmol s−1 and –8.4 ± 6.6 kmol s−1, respectively). Using a standard Redfield ratio of C : N = 106 : 16, nitrate consumption rates indicate that about 40 TgC yr−1 of carbon is fixed by organic matter production between the OVIDE transect and the Greenland–Scotland Ridge. Nutrient fluxes also induce a net biological production of oxygen of 73 ± 60 kmol s−1 and 79 ± 62 kmol s−1 in the Irminger and NEEB boxes, which points to the region as being autotrophic. The abiotic air–sea oxygen flux leads to an oceanic oxygen uptake in the two regions (264 ± 66 kmol s−1 in the north and 443 ± 70 kmol s−1 in the south). The abiotic flux is partitioned into a mixing and a thermal component. It is found that the Irminger Sea oceanic oxygen uptake is driven by an air–sea heat flux cooling increasing the ocean surface oxygen solubility. Over the northeastern European basin the mixing component is about half the thermal flux, presumably because of the oxygen minimum in the subtropical thermocline.

References 1

\'Alvarez, M., Bryden, H., Perez, F., Rios, A., and Roson, G.: Physical and biogeochemical fluxes and net budgets in the subpolar and temperate North Atlantic, J. Mar. Res., 60, 191–226, 2002.

\'Alvarez, M., R\'ios, A. F., Pérez, F. F., Bryden, H. L., and Rosón, G.: Transports and budgets of total inorganic carbon in the subpolar and temperate North Atlantic, Global Biogeochem. Cy., 17, 1002–1023, <a href="http://dx.doi.org/10.1029/2002GB001881">https://doi.org/10.1029/2002GB001881</a>, 2003.

Anderson, L. A.: On the hydrogen and oxygen content of marine phytoplankton, Deep Sea Res. I, 42, 1675–1680, 1995.

Benson, B. and Krause Jr., D.: The concentration and isotopic fractionation of oxygen dissolved in freshwater and seawater in equilibrium with the atmosphere, Limnol. Oceanogr., 29, 620–632, 1984.

Bopp, L., Quéré, C. L., Heimann, M., Manning, A. C., and Monfray, P.: Climate-induced oceanic oxygen fluxes: Implications for the contemporary carbon budget, Global Biogeochem. Cy., 16, 1022–1045, <a href="http://dx.doi.org/10.1029/2001GB001445">https://doi.org/10.1029/2001GB001445</a>, 2002.

Bower, A., Le Cann, B., Rossby, T., Zenk, W., Gould, J., Speer, K., Richardson, P., Prater, M., and Zhang, H.: Directly measured mid-depth circulation in the northeastern North Atlantic Ocean, Nature, 419, 603–607, 2002.

Brambilla, E. and Talley, L. D.: Subpolar Mode Water in the \textsc{N}orth\textsc{E}astern \textsc{A}tlantic. \textsc{P}art \textsc{I}: Averaged properties and mean circulation, J. Geophys. Res., 113, C04025, <a href="http://dx.doi.org/10.1029/2006JC004062">https://doi.org/10.1029/2006JC004062</a>, 2008.

Brambilla, E., Talley, L. D., and Robbins, P. E.: Subpolar Mode Water in the \textsc{N}orth\textsc{E}astern \textsc{A}tlantic. \textsc{P}art \textsc{II}: Origin and transformation, J. Geophys. Res., 113, C04026, <a href="http://dx.doi.org/10.1029/2006JC004063">https://doi.org/10.1029/2006JC004063</a>, 2008.

Broecker, W. S.: NO, a conservative water-mass tracer, Earth Planet. Sci. Lett., 23, 100–107, 1974.

de Boisséson, E., Thierry, V., Mercier, H., and Caniaux, G.: Mixed layer heat budget in the Iceland Basin from Argo, J. Geophys. Res., 115, C10055, <a href="http://dx.doi.org/10.1029/2010JC006283">https://doi.org/10.1029/2010JC006283</a>, 2010.

de Boisséson, E., Thierry, V., Mercier, H., Desbruyères, D., and Caniaux, G.: Origin, formation and variability of the Subpolar Mode Water located over the Reykjanes Ridge in the ORCA025-G70 simulation, J. Geophys. Res., accepted, 2012.

Dickson, B., Dye, S., Jónsson, S., K{ö}hl, A., Macrander, A., Marnela, M., Meincke, J., Olsen, S., Rudels, B., Valdimarsson, H., and Voet, G.: The Overflow Flux West of Iceland: Variability, Origins and Forcing. In Arctic–Subarctic Ocean Fluxes: Defining the Role of the Northern Seas in Climate., chap. 19, Springer Netherlands, 2008a.

Dickson, R. R., Meincke, J., and Rhines, P.: Arctic–Subarctic Ocean Fluxes: Defining the Role of the Northern Seas in Climate, Springer Netherlands, 2008b.

Dietze, H. and Oschlies, A.: On the correlation between air-sea heat flux and abiotically induced oxygen gas exchange in a circulation model of the North Atlantic, J. Geophys. Res., 110, C09016, <a href="http://dx.doi.org/10.1029/2004JC002453">https://doi.org/10.1029/2004JC002453</a>, 2005.

Eldevik, T., Nilsen, J. E. O., Iovino, D., Anders Olsson, K., Sando, A. B., and Drange, H.: Observed sources and variability of Nordic seas overflow, Nature Geosci., 2, 406–410, 2009.

Falina, A., Sarafanov, A., and Sokov, A.: Variability and renewal of Labrador Sea Water in the Irminger Basin in 1991–2004, J. Geophys. Res., 112, C01006, <a href="http://dx.doi.org/10.1029/2005JC003348">https://doi.org/10.1029/2005JC003348</a>, 2007.

Garcia, H. E., Boyer, T. P., Levitus, S., Locarnini, R. A., and Antonov, J.: On the variability of dissolved oxygen and apparent oxygen utilization content for the upper world ocean: 1955 to 1998, Geophys. Res. Lett., 32, L09604, <a href="http://dx.doi.org/10.1029/2004GL022286">https://doi.org/10.1029/2004GL022286</a>, 2005.

Gourcuff, C., Lherminier, P., Mercier, H., and Le Traon, P. Y.: Altimetry combined with hydrography for ocean transport estimation, J. Atmos. Ocean. Tech., 28, 1324–1337, <a href="http://dx.doi.org/10.1175/2011JTECHO818.1">https://doi.org/10.1175/2011JTECHO818.1</a>, 2011.

Hall, N. M. J., Barnier, B., Penduff, T., and Molines, J. M.: Interannual variation of Gulf Stream heat transport in a high-resolution model forced by reanalysis data, Clim. Dynam., 23, 341–351, 2004.

Hansen, B. and Østerhus, S.: Faroe Bank Channel overflow 1995–2005, Prog. Oceanogr., 75, 817–856, 2007.

Hansen, B., Østerhus, S., Turrell, W., J{ó}nsson, S., Valdimarsson, H., H{á}t{ú}n, H., and Olsen, S.: The Inflow of Atlantic Water, Heat, and Salt to the Nordic Seas Across the Greenland-Scotland Ridge, in: Arctic-Subarctic Ocean Fluxes: Defining the Role of the Northern Seas in Climate, chap. 1, 15–43, Springer Netherlands, 2008.

J{ó}nsson, S. and Valdimarsson, H.: The flow of Atlantic water to the North Icelandic Shelf and its relation to the drift of cod larvae, ICES Journal of Marine Science: Journal du Conseil, 62, 1350–1359, 2005.

Kahler, P. and Koeve, W.: Marine dissolved organic matter: can its \textsc{C:N} ratio explain carbon overconsumption?, Deep Sea Res. I, 48, 49–62, 2001.

Kalnay, E., Kanamitsu, M., Kistler, R., Collins, W., Deaven, D., Gandin, L., Iredell, M., Saha, S., White, G., Woollen, J., Zhu, Y., Chelliah, M., Ebisuzaki, W., Higgins, W., Janowiak, J., Mo, K. C., Ropelewski, C., Wang, J., Leetmaa, A., Reynolds, R., Jenne, R., and Joseph, D.: The NCEP-NCAR 40-year Reanalysis Project, B. Am. Meteorol. Soc., 77, 437–470, 1996.

Keeling, R. F., Najjar, R. P., Bender, M. L., and Tans, P. P.: What Atmospheric Oxygen Measurements Can Tell Us About the Global Carbon Cycle, Global Biogeochem. Cy., 7, 37–67, <a href="http://dx.doi.org/10.1029/92GB02733">https://doi.org/10.1029/92GB02733</a>, 1993.

K{ö}rtzinger, A., Send, U., Wallace, D. W. R., Karstensen, J., and DeGrandpre, M.: Seasonal cycle of O2 and pCO2 in the central Labrador Sea: Atmospheric, biological, and physical implications, Global Biogeochem. Cy., 22, GB1014, <a href="http://dx.doi.org/10.1029/2007GB003029">https://doi.org/10.1029/2007GB003029</a>, 2008.

Kvaleberg, E., Haine, T. W. N., and Waugh, D. W.: Middepth spreading in the subpolar North Atlantic Ocean: Reconciling CFC-11 and float observations, J. Geophys. Res., 113, C08019, <a href="http://dx.doi.org/10.1029/2007JC004104">https://doi.org/10.1029/2007JC004104</a>, 2008.

Lee, K.: Global net community production estimated from the annual cycle of surface water total dissolved inorganic carbon, Limnol. Oceanogr., 46, 1287–1297, 2001.

Lherminier, P., Mercier, H., Gourcuff, C., Alvarez, M., Bacon, S., and Kermabon, C.: Transports across the 2002 Greenland-Portugal Ovide section and comparison with 1997, J. Geophys. Res., 112, C07003, <a href="http://dx.doi.org/10.1029/2006JC003716">https://doi.org/10.1029/2006JC003716</a>, 2007.

Lherminier, P., Mercier, H., Huck, T., Gourcuff, C., Perez, F. F., Morin, P., Sarafanov, A., and Falina, A.: The Atlantic Meridional Overturning Circulation and the subpolar gyre observed at the A25-OVIDE section in June 2002 and 2004, Deep Sea Res. I, 57, 1374–1391, 2010.

Macrander, A., Send, U., Valdimarsson, H., J{ó}nsson, S., and K{ä}se, R.: Interannual changes in the overflow from the Nordic Seas into the Atlantic Ocean through Denmark Strait, Geophys. Res. Lett, 32, L06606, <a href="http://dx.doi.org/10.1029/2004GL021463">https://doi.org/10.1029/2004GL021463</a>, 2005.

McCartney, M. S., Bennett, S. L., and Woodgate-Jones, M. E.: Eastward Flow through the Mid-Atlantic Ridge at $11^{\circ}\;{\rm N}$ and Its Influence on the Abyss of the Eastern Basin, J. Phys. Oceanogr., 21, 1089–1121, 1991.

Mercier, H.: Determining the General Circulation of the Ocean: A Nonlinear Inverse Problem, J. Geophys. Res., 91, 5103–5109, 1986.

Millard, R. J. and Fofonoff, P.: Algorithms for computation of fundamental properties of seawater, Unesco technical papers in marine science, UNESCO, 1983.

Najjar, R. G. and Keeling, R. F.: Mean Annual Cycle of the Air-Sea Oxygen Flux: A Global View, Global Biogeochem. Cy., 14, 573–584, <a href="http://dx.doi.org/10.1029/1999GB900086">https://doi.org/10.1029/1999GB900086</a>, 2000.

Peng, T. H., Takahashi, T., Broecker, W. S., and Olafsson, J.: Seasonal variability of carbon dioxide, nutrients and oxygen in the northern North Atlantic surface water: observations and a model, Tellus B, 39B, 439–458, 1987.

Pérez, F. F., Castro, C. G., R\`ios, A. F., and Fraga, F.: Chemical properties of the deep winter mixed layer in the Northeast Atlantic (40–47$^\circ\;{\rm N}$), J. Marine Syst., 54, 115–125, 2005.

Pickart, R., Spall, M. A., Ribergaard, M. H., Moore, G. W. K., and Milliff, R. F.: Deep convection in the Irminger Sea forced by the Greenland tip jet, Nature, 424, 152–156, 2003a.

Pickart, R., Straneo, F., and Moore, G. W. K.: Is Labrador Sea Water formed in the Irminger basin?, Deep-Sea Res. I, 50, 23–52, 2003b.

Pickart, R. S., Torres, D. J., and Fratantoni, P. S.: The East Greenland Spill Jet, J. Phys. Oceanogr., 35, 1037–1053, 2005.

Sambrotto, R. N., Savidge, G., Robinson, C., Boyd, P., Takahashi, T., Karl, D. M., Langdon, C., Chipman, D., Marra, J., and Codispoti, L.: Elevated consumption of carbon relative to nitrogen in the surface ocean, Nature, 363, 248–250,1993.

Sarafanov, A., Falina, A., Sokov, A., and Demidov, A.: Intense warming and salinification of intermediate waters of southern origin in the eastern North Atlantic in the 1990s to mid-2000s, J. Geophys. Res., 113, C12022, <a href="http://dx.doi.org/10.1029/2008JC004975">https://doi.org/10.1029/2008JC004975</a>, 2008.

Schott, F. A., Zantopp, R., Stramma, L., Dengler, M., Fischer, J., and Wibaux, M.: Circulation and Deep-Water Export at the Western Exit of the Subpolar North Atlantic, J. Phys. Oceanogr., 34, 817–843, 2004.

Sproson, D. A. J., Renfrew, I. A., and Heywood, K. J.: Atmospheric conditions associated with oceanic convection in the south-east Labrador Sea, Geophys. Res. Lett., 35, L06601, <a href="http://dx.doi.org/10.1029/2007GL032971">https://doi.org/10.1029/2007GL032971</a>, 2008.

Tarantola, A. and Valette, B.: Generalized nonlinear inverse problems solved using the least squares criterion, Rev. Geophys. Space Phys., 20, 219–232, 1982.

Thierry, V., de Boisséson, E., and Mercier, H.: Interannual variability of the Subpolar Mode Water properties over the Reykjanes Ridge during 1990–2006, J. Geophys. Res., 113, C04016, <a href="http://dx.doi.org/10.1029/2007JC004443">https://doi.org/10.1029/2007JC004443</a>, 2008.

Toggweiler, J. R.: Carbon overconsumption, Nature, 363, 210–211, 1993.

Treguier, A. M., Theetten, S., Chassignet, E. P., Penduff, T., Smith, R., Talley, L., Beismann, J. O., and B{ö}ning, C.: The North Atlantic Subpolar Gyre in Four High-Resolution Models, J. Phys. Oceanogr., 35, 757–774, 2005.

Treguier, A.-M., Gourcuff, C., Lherminier, P., Mercier, H., Barnier, B., Madec, G., Molines, J.-M., Penduff, T., Czeschel, L., and Böning, C.: Internal and forced variability along a section between Greenland and Portugal in the CLIPPER Atlantic model, Oc. Dyn., 56, 568–580, 2006.

van Aken, H. M. and de Boer, C.J. : On the synoptic hydrography of intermediate and deep water masses in the Iceland Basin, Deep Sea Res. I, 42, 165–189, 1995.

van Aken, H. M. and Becker, G.: Hydrography and through-flow in the northeastern North Atlantic Ocean: The NANSEN project, Prog. Oceanogr., 38, 297–346, 1996.

van Aken, H. M., Femke de Jong, M., and Yashayaev, I.: Decadal and multi-decadal variability of labrador sea water in the north-western north atlantic ocean derived from tracer distributions: Heat budget, ventilation, and advection, Deep Sea Res. I, 58, 505–523, 2011.

Yashayaev, I.: Hydrographic changes in the Labrador Sea, 1960–2005, Prog. Oceanogr., 73, 242–276, 2007.

Yashayaev, I., Bersch, M., and van Aken, H. M.: Spreading of the Labrador Sea Water to the Irminger and Iceland basins, Geophys. Res. Lett., 34, L10602, <a href="http://dx.doi.org/10.1029/2006GL028999">https://doi.org/10.1029/2006GL028999</a>, 2007.

Yu, L., Jin, X., and Weller, R. A.: Multidecade Global Flux Datasets from the Objectively Analyzed Air-sea Fluxes (OAFlux) Project: Latent and Sensible Heat Fluxes, Ocean Evaporation, and Related Surface Meteorological Variables, Tech. rep., Woods Hole Oceanographic Institute, 2008.