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

Fernández-Castro, B.; Mouriño‐Carballido, Beatriz; Benítez-Barrios, V.M.; Chouciño, P.; Fraile-Nuez, E.; Graña, R.; Piedeleu, M.; Rodríguez-Santana, Ángel

doi:10.1016/j.dsr.2014.08.006

Cited by 41 publications

(32 citation statements)

References 72 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Here, we have calculated N 2 between the 70% PAR (3 m) and 150 m. Furthermore, we have also calculated the gradients of potential temperature and salinity (D θ and D S ) over the upper 150 m, which were obtained as the difference between the potential temperature or salinity at 70% PAR (about 3 m) and 150 m divided by the difference in depth (147 m). The mixed layer depth (MLD) was calculated as the depth where potential density exceeded the value at 3 m by 0.1 kg m −3 (Fernández‐Castro et al ). Daily, weekly and monthly short wave (wavelength range, 175–3850 nm) solar radiation data (SWR, in MJ m −2 d −1 ) were obtained from the National Centres for Environmental Predictions NCEP/DOE 2 reanalysis database provided by the NOAA/OAR/ESRL PSD, Boulder, Colorado, U.S.A., (http://www.esrl.noaa.gov/psd/) and interpolated for each station.…”

Section: Methodsmentioning

confidence: 99%

Drivers of fluorescent dissolved organic matter in the global epipelagic ocean

Catalá

Álvarez‐Salgado

Otero

et al. 2016

Limnology & Oceanography

View full text Add to dashboard Cite

Section: Methodsmentioning

confidence: 99%

Drivers of fluorescent dissolved organic matter in the global epipelagic ocean

Catalá

Álvarez‐Salgado

Otero

et al. 2016

Limnology & Oceanography

View full text Add to dashboard Cite

“…These numbers represent the first estimate of the contribution of both processes in a coastal upwelling system. Few studies have simultaneously quantified BNF and nitrate diffusion (Mouriño-Carballido et al, 2011;Painter et al, 2013;Fernández-Castro et al, 2015), mainly due to the methodological difficulties to estimate vertical mixing (Kz) in the field, which has frequently motivated the use of constant values of Kz , and empirical parameterizations (Planas et al, 1999;Fernández-Castro et al, 2014). Capone et al (2005) estimated in the tropical North Atlantic that BNF could equal or even exceed nitrate vertical diffusion into the euphotic zone.…”

Section: Magnitude and Biogeochemical Relevance Of Bnfmentioning

confidence: 99%

“…Due to significant turbulence generation close to the ship, only the data below 5 m were considered reliable. Data processing and calculation of dissipation rates of turbulent kinetic energy (ε) was carried out with the commercial software MSSpro as described in detail in Fernández-Castro et al (2014). The squared Brunt Väisälä frequency (N 2 ), a proxy for water column stratification, was computed from the CTD profiles according to the equation:…”

Section: Dissipation Rates Of Turbulent Kinetic Energy and Estimates mentioning

confidence: 99%

Biological N2 Fixation in the Upwelling Region off NW Iberia: Magnitude, Relevance, and Players

et al. 2017

View full text Add to dashboard Cite

The classical paradigm about marine N 2 fixation establishes that this process is mainly constrained to nitrogen-poor tropical and subtropical regions, and sustained by the colonial cyanobacterium Trichodesmium spp. and diatom-diazotroph symbiosis. However, the application of molecular techniques allowed determining a high phylogenic diversity and wide distribution of marine diazotrophs, which extends the range of ocean environments where biological N 2 fixation may be relevant. Between February 2014 and December 2015, we carried out 10 one-day samplings in the upwelling system off NW Iberia in order to: (1) investigate the seasonal variability in the magnitude of N 2 fixation, (2) determine its biogeochemical role as a mechanism of new nitrogen supply, and (3) quantify the main diazotrophs in the region under contrasting hydrographic regimes. Our results indicate that the magnitude of N 2 fixation in this region was relatively low (0.001 ± 0.002 -0.095 ± 0.024 µmol N m −3 d −1 ), comparable to the lower-end of rates described for the subtropical NE Atlantic. Maximum rates were observed at the surface during both upwelling and relaxation conditions. The comparison with nitrate diffusive fluxes revealed the minor role of N 2 fixation (<2%) as a mechanism of new nitrogen supply into the euphotic layer. Small diazotrophs (<10 µm) were responsible for all N 2 fixation activity detected in the region. Quantitative PCR targeting the nifH gene revealed the highest abundances of two sublineages of Candidatus Atelocyanobacterium thalassa or UCYN-A (UCYN-A1 and UCYN-A2), mainly at surface waters during upwelling and relaxation conditions, and of Gammaproteobacteria γ-24774A11 at deep waters during downwelling. Maximum abundance for the three groups were up to 6.7 × 10 2 , 1.5 × 10 3 , and 2.4 × 10 4 nifH copies L −1 , respectively. Our findings demonstrate measurable N 2 fixation activity and presence of diazotrophs throughout the year in a nitrogen-rich temperate region.

show abstract

“…Wind mixing, surface heat loss to the atmosphere, wave-generated mixing, shears associated with nearinertial oscillations, and other processes cause turbulence values in the surface ''mixed layer'' to be several decades larger than found deeper in the interior thermocline [Fernandez-Castro et al, 2014]. Diffusive transport through the stratified water column below the base of the mixed layer is typically expressed as a downgradient flux that is proportional to the property gradient, with the proportionality factor referred to as the ''diffusion coefficient'' or ''eddy diffusivity,'' hereinafter referred to simply as ''diffusivity.''…”

Section: Introductionmentioning

confidence: 99%

Estimating diffusivity from the mixed layer heat and salt balances in the North Pacific

et al. 2015

View full text Add to dashboard Cite

Data from two National Oceanographic and Atmospheric Administration (NOAA) surface moorings in the North Pacific, in combination with data from satellite, Argo floats and glider (when available), are used to evaluate the residual diffusive flux of heat across the base of the mixed layer from the surface mixed layer heat budget. The diffusion coefficient (i.e., diffusivity) is then computed by dividing the diffusive flux by the temperature gradient in the 20 m transition layer just below the base of the mixed layer. At Station Papa in the NE Pacific subpolar gyre, this diffusivity is 1 × 10−4 m2/s during summer, increasing to ∼3 × 10−4 m2/s during fall. During late winter and early spring, diffusivity has large errors. At other times, diffusivity computed from the mixed layer salt budget at Papa correlate with those from the heat budget, giving confidence that the results are robust for all seasons except late winter‐early spring and can be used for other tracers. In comparison, at the Kuroshio Extension Observatory (KEO) in the NW Pacific subtropical recirculation gyre, somewhat larger diffusivities are found based upon the mixed layer heat budget: ∼ 3 × 10−4 m2/s during the warm season and more than an order of magnitude larger during the winter, although again, wintertime errors are large. These larger values at KEO appear to be due to the increased turbulence associated with the summertime typhoons, and weaker wintertime stratification.

show abstract

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

Cited by 41 publications

References 72 publications

Drivers of fluorescent dissolved organic matter in the global epipelagic ocean

Drivers of fluorescent dissolved organic matter in the global epipelagic ocean

Biological N2 Fixation in the Upwelling Region off NW Iberia: Magnitude, Relevance, and Players

Estimating diffusivity from the mixed layer heat and salt balances in the North Pacific

Contact Info

Product

Resources

About