Browsing by Author "Dadou, Isabelle"

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    High‐resolution modeling of the Eastern Tropical Pacific oxygen minimum zone: sensitivity to the tropical oceanic circulation
    (American Geophysical Union (AGU), 2014-08) Montes Torres, Ivonne; Dewitte, Boris; Gutknecht, Elodie; Paulmier, Aurélien; Dadou, Isabelle; Oschlies, Andreas; Garçon, Véronique
    The connection between the equatorial mean circulation and the oxygen minimum zone (OMZ) in the Eastern Tropical Pacific is investigated through sensitivity experiments with a high‐resolution coupled physical‐biogeochemical model. A validation against in situ observations indicates a realistic simulation of the vertical and horizontal oxygen distribution by the model. Two sets of climatological open‐boundary conditions for the physical variables, which differ slightly with respect to the intensity and vertical structure of the Equatorial Current System, are shown to lead to contrasting characteristics of the simulated OMZ dynamics. From a Lagrangian perspective, the mean differences near the coast originate to a large extent from the different transport of deoxygenated waters by the secondary Tsuchiya Jet (secondary Southern Subsurface Countercurrent, sSSCC). The O₂ budget further indicates a large difference in the balance between tendency terms, with advection exhibiting the largest difference between both simulations, which is shown to result from both linear and nonlinear advection. At regional scale, we also find that the variability of the physical contribution to the rate of O₂ change is one order of magnitude larger than the variability associated with the biogeochemical contribution, which originates from internal high‐frequency variability. Overall our study illustrates the large sensitivity of the OMZ dynamics to the equatorial circulation.
    Palabras clave:OMZEastern Tropical PacificEquatorial Current System
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    Inference of super-resolution ocean pCO₂ and air-sea CO₂ fluxes from non-linear and multiscale processing methods
    (EGU General Assembly, 2014) Hernández Carrasco, Ismael; Sudre, Joel; Garçon, Veronique; Yahia, Hussein; Dewitte, Boris; Garbe, Christoph; Illig, Serena; Montes Torres, Ivonne; Dadou, Isabelle; Paulmier, Aurélien; Butz, André
    In recent years the role of submesoscale activity is emerging as being more and more important to understand global ocean properties, for instance, for accurately estimating the sources and sinks of Greenhouse Gases (GHGs) at the air-sea interface. The scarcity of oceanographic cruises and the lack of available satellite products for GHG concentrations at high resolution prevent from obtaining a global assessment of their spatial variability at small scales. In this work we develop a novel method to reconstruct maps of CO₂ fluxes at super resolution (4km) using SST and ocean colour data at this resolution, and CarbonTracker CO₂ fluxes data at low resolution (110 km). The responsible process for propagating the information between scales is related to cascading properties and multiscale organization, typical of fully developed turbulence. The methodology, based on the Microcanonical Multifractal Formalism, makes use, from the knowledge of singularity exponents, of the optimal wavelet for the determination of the energy injection mechanism between scales. We perform a validation analysis of the results of our algorithm using pCO₂ ocean data from in-situ measurements in the upwelling region off Namibia.
    Palabras clave:Greenhouse gasesAir-sea interactionOceanography