Diapycnal nutrient fluxes on the northern boundary of Cape Ghir upwelling region

Arcos-Pulido, M.; Rodríguez-Santana, Ángel; Emelianov, Mikhail; Пака, В. Т.; Arı́stegui, Javier; Benavides, Mar; Sangrà, Pablo; Machín, Francisco; García-Weil, L.; Estrada-Allis, Sheila N.

doi:10.1016/j.dsr.2013.10.010

Cited by 13 publications

(20 citation statements)

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“…In the central waters of the oceans, the most important turbulent diffusion processes are the mechanical mixing generated by the horizontal shear of the currents and the salt fingers (McDougall and Ruddick, 1992). These two processes have been observed coexisting in similar magnitudes ( K T ≈ K sf ≈10 −5 ) in the Canary upwelling system (east coast of the North Atlantic), where mechanical mixing was more important on the surface, since under the thermocline, double diffusion is the dominant process at the depth of the NACW waters (Arcos-Pulido et al, 2014). Our observations also show the presence of these two diffusive processes in the SCUS, although the mechanical mixing is ~ 2 orders of magnitude more intense (~ 10 -3 ) in the whole water column and dominates the double diffusion even at the depth of the wNACW (~ 300 m).…”

Section: Discussionmentioning

confidence: 99%

“…The nutrients diffusion by salt fingers of has not been analyzed in the SCUS, although this information could be important to completely understand the balance of nutrients and the biological production observed in the system. In the Canary upwelling system located on the eastern edge of the North Atlantic, salt fingers generate an important vertical transport of nutrients comparable to other turbulent processes of vertical nutrient mixing (Arcos-Pulido et al, 2014). In the SCUS, the mechanical mixing exceeds the double diffusion mainly in the surface, which can modify the concentration of nutrients of the SUW waters that eventually reach the surface in the upwelling system.…”

Section: Discussionmentioning

confidence: 99%

“…Some estimations suggest that the turbulent mixing processes transport to surface about 25% of the upwelled nutrients in EBCS, transport that is not reversible during the periods of upwelling relaxation when the isopycnals descend to their original depth (Hales, 2005). In addition, the higher salt concentration in the subsurface waters compared to the water below them, makes these waters prone to undergo double diffusion processes, which coexist along with turbulent mixing processes in upwelling systems (Arcos-Pulido et al, 2014). In mid latitudes, instabilities generated by double diffusion processes can generate nutrient fluxes similar in magnitude to those induced by mechanical turbulence or mesoscale eddies (Oschlies et al, 2003).…”

Section: Introducctionmentioning

confidence: 99%

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Water masses and mixing processes in the Southern Caribbean upwelling system off Colombia

Correa-Ramírez

Rodríguez-Santana

Ricaurte-Villota

et al. 2019

Preprint

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Abstract. The upwelling system off the southern Caribbean coast is probably the main nutrients source that support the biological productivity in this oligotrophic sea. The Subtropical Water Mass (SUW) that forms the subsurface salinity maximum in the Caribbean is the main source of upwelled waters in this system. Salinity and temperature vs. depth profiles from 4 oceanographic cruises in the western sector of the Caribbean upwelling system, showed that the salinity of upwelled SUW waters is ~ 0.2 g kg−1 lower than the SUW salinity in the central Caribbean and have a slight seasonal variation that agree with with the rainy/dry seasons in the region. Besides, the depth of these SUW waters in the continental slope (~ 100 m) is ~ 50 m shallower than the SUW depth in the rest of the Caribbean sea. The origin of these modified SUW waters was analyzed using the Mercator numerical model, which reproduces the main vertical characteristics of the subsurface salinity maximum. Modeled data showed that SUW waters upwelled off La Guajira peninsula come from the western Caribbean and arrive to the system transported by an intense Caribbean Coastal Undercurrent (CaCU, mean speed ~ 0.4 m s−1). The lower salinity observed in the upwelled SUW waters may be the result of intense vertical mixing processes with diluted surface waters in the Panama-Colombia gyro that could occur when the CaCU flows below this region before reaching the upwelling zones. The mixing processes in the SUW by double diffusion and mechanical turbulence driven by vertical shear of horizontal currents, were analyzed using the Turner angle and the Thorpe scale, respectively. Double diffusion by salt fingers was found between the SUW and the Central North Atlantic Waters (NACW) with diffusivity values ~ 10−5 m2 s−1. But the mechanical diffusivity was two orders of magnitude higher (10−3 m2 s−1.) than the double diffusivities in the entire water column, generating salt fluxes from the SUW towards surface and towards depth over 2 g kg−1 m d−1. Beyond modifying the salt content in coastal SUW waters, these mixing processes may also alter the nutrient content of upwelling waters, with effects still unknown to the upwelling ecosystem.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introducctionmentioning

confidence: 99%

See 1 more Smart Citation

Water masses and mixing processes in the Southern Caribbean upwelling system off Colombia

Correa-Ramírez

Rodríguez-Santana

Ricaurte-Villota

et al. 2019

Preprint

View full text Add to dashboard Cite

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“…Capone et al (2005) reported Trichodesmiumassociated integrated N 2 fixation rates averaging 239 µmol N m −2 d −1 (but up to 19235 µmol N m −2 d −1 , see Table 3), while Mouriño-Carballido et al (2011) and Painter et al (2013) reported bulk seawater N 2 fixation rates ranging from 1.3 to 154.5 µmol N m −2 d −1 and 15.4 to 95.6 µmol N m −2 d −1 , respectively. Thus, it is clear that the contribution of N 2 fixation to new production is greater in Trichodesmium-dominated waters of the NWA , whereas minimal in the UCYN-dominated waters of the NEA (Benavides et al, 2013b;Arcos-Pulido et al, 2014).…”

Section: N 2 Fixation Contribution To New Production and Nitrogen Excmentioning

confidence: 98%

“…In addition, the inherent seasonal variability of the NA, and the intermittent nature of mesoscale and submesoscale features may result in a highly variable contribution of N 2 fixation to new production (Mouriño-Carballido et al, 2011;Painter et al, 2013). Finally, other factors such as the application of theoretical vs. empirical estimated turbulent diffusion coefficients (K z ) (Mouriño-Carballido et al, 2011;Arcos-Pulido et al, 2014), biases derived from measuring N 2 fixation on sporadic Trichodesmium blooms (which might be not be representative of the long-term situation; Capone et al, 2005), 15 N 2 method underestimations (Mohr et al, 2010), or overestimations (Dabundo et al, 2014 see discussion below), and substantial nitrate regeneration in the photic zone (Yool et al, 2007), may also play an important role.…”

Section: N 2 Fixation Contribution To New Production and Nitrogen Excmentioning

confidence: 99%

Five decades of N2 fixation research in the North Atlantic Ocean

Benavides

Voß

2015

Front. Mar. Sci.

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Dinitrogen (N 2 ) fixation (the reduction of atmospheric N 2 to ammonium by specialized prokaryotic microbes), represents an important input of fixed nitrogen and contributes significantly to primary productivity in the oceans. Marine N 2 fixation was discovered in the North Atlantic Ocean (NA) in the 1960s. Ever since, the NA has been subject to numerous studies that have looked into the diversity and abundance of N 2 -fixing microbes (diazotrophs), the spatial and temporal variability of N 2 fixation rates, and the range of physical and chemical variables that control them. The NA provides 10-25% of the globally fixed N 2 , ranking as the third basin with the largest N 2 fixation inputs in the world's oceans. This basin suffers a chronic depletion in phosphorus availability, more aeolian dust deposition than any other basin in the world's oceans, and significant nutrient inputs from important rivers like the Amazon and the Congo. These characteristics make it unique in comparison with other oceanic basins. After five decades of intensive research, here we present a comprehensive review of our current understanding of diazotrophic activity in the NA from both a geochemical and biological perspective. We discuss the advantages and disadvantages of current methods, future perspectives, and questions which remain to be answered.

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Microstructure turbulence and diffusivity parameterization in the tropical and subtropical Atlantic, Pacific and Indian Oceans during the Malaspina 2010 expedition

Fernández-Castro

Mouriño‐Carballido

Benítez-Barrios

et al. 2014

Deep Sea Research Part I: Oceanographic Research Papers

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Diapycnal nutrient fluxes on the northern boundary of Cape Ghir upwelling region

Cited by 13 publications

References 50 publications

Water masses and mixing processes in the Southern Caribbean upwelling system off Colombia

Water masses and mixing processes in the Southern Caribbean upwelling system off Colombia

Five decades of N2 fixation research in the North Atlantic Ocean

Microstructure turbulence and diffusivity parameterization in the tropical and subtropical Atlantic, Pacific and Indian Oceans during the Malaspina 2010 expedition

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