Browsing by Author "Sudre, Joel"

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    Balance geostrófico y ageostrófico frente a la costa peruana entre 1980 y 2008
    (Instituto Geofísico del Perú, 2018-04) Aparco, Tony; Montes Torres, Ivonne; Sudre, Joel
    Las corrientes superficiales oceánicas son de crucial interés debido a que transportan momentum, calor, salinidad y propiedades de un lugar a otro; permitiendo regular localmente y a grandes escalas las condiciones climáticas (Sudre et al., 2013). Dentro de este margen, la estimación de corrientes geostróficas y ageostróficas se han convertido en un método relevante para, en conjunto, aproximarse a las corrientes reales superficiales (Sudre and Morrow, 2008; Rio et al., 2013). Estas estimaciones de corrientes son obtenidas mediante la simplificación de la ecuación de movimiento (ecuación que describe la dinámica del océano, ec. 1) bajo ciertos supuestos, tales como que el océano se comporta como un medio homogéneo, ocupa una gran extensión espacial donde las aceleraciones locales son despreciables. Por lo tanto, la circulación oceánica en superficie queda regida por los principales forzantes de movimiento, externos e internos, como el viento que interactúa superficialmente y promueve el movimiento y el gradiente de presión horizontal (Rio et al., 2013).
    Palabras clave:Corrientes marinasCirculación oceánicaTemperatura del mar
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    Dynamics of the carbonate system across the Peruvian Oxygen Minimum Zone
    (Frontiers Media, 2019-10-16) Hernandez-Ayon, Jose M.; Paulmier, Aurélien; Garcon, Veronique; Sudre, Joel; Montes Torres, Ivonne; Chapa-Balcorta, Cecilia; Durante, Giovanni; Dewitte, Boris; Maes, Cristophe; Bretagnon, Marine
    The oxygen minimum zone (OMZ) of Peru is recognized as a source of CO₂ to the atmosphere due to upwelling that brings water with high concentrations of dissolved inorganic carbon (DIC) to the surface. However, the influence of OMZ dynamics on the carbonate system remains poorly understood given a lack of direct observations. This study examines the influence of a coastal Eastern South Pacific OMZ on carbonate system dynamics based on a multidisciplinary cruise that took place in 2014. During the cruise, onboard DIC and pH measurements were used to estimate pCO₂ and to calculate the calcium carbonate saturation state ( Ω aragonite and calcite). South of Chimbote (9ºS), water stratification decreased and both the oxycline and carbocline moved from 150m depth to 20–50m below the surface. The aragonite saturation depth was observed to be close to 50m. However, values <1.2 were detected close to 20m along with low pH (minimum of 7.5), high pCO2 (maximum 1,250μatm), and high DIC concentrations (maximum 2,300 μmol kg⁻¹). These chemical characteristics are shown to be associated with Equatorial Subsurface Water (ESSW). Large spatial variability in surface values was also found. Part of this variability can be attributed to the influence of mesoscale eddies, which can modify the distribution of biogeochemical variables, such as the aragonite saturation horizon, in response to shallower (cyclonic eddies) or deeper (anticyclonic eddies) thermoclines. The analysis of a 21-year (1993–2014) data set of mean sea surface level anomalies (SSHa) derived from altimetry data indicated that a large variance associated with interannual timescales was present near the coast. However, 2014 was characterized by weak Kelvin activity, and physical forcing was more associated with eddy activity. Mesoscale activity modulates the position of the upper boundary of ESSW, which is associated with high DIC and influences the carbocline and aragonite saturation depths. Weighing the relative importance of each individual signal results in a better understanding of the biogeochemical processes present in the area.
    Palabras clave:OMZDICpH
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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