Santana-Casiano J. M.

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J. M.

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  • Article
    Regional differences in modelled net production and shallow remineralization in the North Atlantic subtropical gyre
    (Copernicus Publications on behalf of the European Geosciences Union, 2012-08-01) Fernandez-Castro, B. ; Anderson, Laurence A. ; Marañón, Emilio ; Neuer, Susanne ; Ausiin, B. ; Gonzalez-Davila, M. ; Santana-Casiano, J. M. ; Cianca, Andrés ; Santana, R. ; Llinas, Octavio ; Rueda, María José ; Mourino-Carballido, Beatriz
    We used 5-yr concomitant data of tracer distribution from the BATS (Bermuda Time-series Study) and ESTOC (European Station for Time-Series in the Ocean, Canary Islands) sites to build a 1-D tracer model conservation including horizontal advection, and then compute net production and shallow remineralization rates for both sites. Our main goal was to verify if differences in these rates are consistent with the lower export rates of particulate organic carbon observed at ESTOC. Net production rates computed below the mixed layer to 110 m from April to December for oxygen, dissolved inorganic carbon and nitrate at BATS (1.34±0.79 mol O2 m−2, −1.73±0.52 mol C m−2 and −125±36 mmol N m−2) were slightly higher for oxygen and carbon compared to ESTOC (1.03±0.62 mol O2 m−2, −1.42±0.30 mol C m−2 and −213±56 mmol N m−2), although the differences were not statistically significant. Shallow remineralization rates between 110 and 250 m computed at ESTOC (−3.9±1.0 mol O2 m−2, 1.53±0.43 mol C m−2 and 38±155 mmol N m−2) were statistically higher for oxygen compared to BATS (−1.81±0.37 mol O2 m−2, 1.52±0.30 mol C m−2 and 147±43 mmol N m−2). The lateral advective flux divergence of tracers, which was more significant at ESTOC, was responsible for the differences in estimated oxygen remineralization rates between both stations. According to these results, the differences in net production and shallow remineralization cannot fully explain the differences in the flux of sinking organic matter observed between both stations, suggesting an additional consumption of non-sinking organic matter at ESTOC.
  • Article
    An assessment of the Atlantic and Arctic sea–air CO2 fluxes, 1990–2009
    (Copernicus Publications on behalf of the European Geosciences Union, 2013-01-29) Schuster, Ute ; McKinley, Galen A. ; Bates, Nicholas R. ; Chevallier, Frédéric ; Doney, Scott C. ; Fay, A. R. ; Gonzalez-Davila, M. ; Gruber, Nicolas ; Jones, S. ; Krijnen, J. ; Landschutzer, Peter ; Lefevre, N. ; Manizza, Manfredi ; Mathis, Jeremy T. ; Metzl, Nicolas ; Olsen, Are ; Rios, Aida F. ; Rodenbeck, C. ; Santana-Casiano, J. M. ; Takahashi, Taro ; Wanninkhof, Rik ; Watson, Andrew J.
    The Atlantic and Arctic Oceans are critical components of the global carbon cycle. Here we quantify the net sea–air CO2 flux, for the first time, across different methodologies for consistent time and space scales for the Atlantic and Arctic basins. We present the long-term mean, seasonal cycle, interannual variability and trends in sea–air CO2 flux for the period 1990 to 2009, and assign an uncertainty to each. We use regional cuts from global observations and modeling products, specifically a pCO2-based CO2 flux climatology, flux estimates from the inversion of oceanic and atmospheric data, and results from six ocean biogeochemical models. Additionally, we use basin-wide flux estimates from surface ocean pCO2 observations based on two distinct methodologies. Our estimate of the contemporary sea–air flux of CO2 (sum of anthropogenic and natural components) by the Atlantic between 40° S and 79° N is −0.49 ± 0.05 Pg C yr−1, and by the Arctic it is −0.12 ± 0.06 Pg C yr−1, leading to a combined sea–air flux of −0.61 ± 0.06 Pg C yr−1 for the two decades (negative reflects ocean uptake). We do find broad agreement amongst methodologies with respect to the seasonal cycle in the subtropics of both hemispheres, but not elsewhere. Agreement with respect to detailed signals of interannual variability is poor, and correlations to the North Atlantic Oscillation are weaker in the North Atlantic and Arctic than in the equatorial region and southern subtropics. Linear trends for 1995 to 2009 indicate increased uptake and generally correspond between methodologies in the North Atlantic, but there is disagreement amongst methodologies in the equatorial region and southern subtropics.