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The abundance and distribution of plastic debris at the sea surface shows considerable variability over different spatial scales. Some of the oceanographic processes at small (<1 km) and submeso (1–10 km) scales manifest themselves as... more
The abundance and distribution of plastic debris at the sea surface shows considerable variability over different spatial scales. Some of the oceanographic processes at small (<1 km) and submeso (1–10 km) scales manifest themselves as slicks at the sea surface, which might have the potential to concentrate organisms and particles (such as positively buoyant plastics), putting species that feed in these areas at risk of ingesting plastics. Slicks can be filaments, lines, meanders, or patches, which are lighter in color and smoother in surface roughness compared to the surrounding area. Here we tested the hypothesis that passive particles (including plastics) and organisms are aggregated in the surface waters within these slicks. According to their main features (orientation to coast and/or wind), the studied slicks were most likely generated by oceanographic processes such as topographically controlled fronts, other types of fronts and internal waves. Neuston samples were collecte...
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Many seaweed species are particularly important for passive marine dispersal, yet relatively little is known about their floating and stranding dynamics. Here, we studied these dynamics for two kelp species over four consecutive years at... more
Many seaweed species are particularly important for passive marine dispersal, yet relatively little is known about their floating and stranding dynamics. Here, we studied these dynamics for two kelp species over four consecutive years at mid‐latitudes (30°S). Floating kelps were found during all seasons, but Macrocystis pyrifera was always more abundant than Durvillaea incurvata. Highest floating biomasses were reached during summer and fall, whereas considerable stranded biomasses on nearby shores were only observed during summer. The proportion of fragments among the floating kelps was high throughout the entire study period and highest for M. pyrifera during summer. At the same time, blades of M. pyrifera that floated in nearshore waters in summer had a high blade index and thus were intact (i.e., not yet compromised by unfavorable environmental conditions). These results suggest that during summer, floating kelps become quickly resupplied from benthic sources, which compensates their frequent losses due to degradation and stranding. During fall, biomasses of floating kelps remain high because of reduced losses. Interestingly, increased wind speed was a good predictor for the biomass accumulations of the two kelp species, although the floating biomass of M. pyrifera was additionally influenced by oceanographic fronts. Our findings suggest that at mid‐latitudes the dynamics of floating seaweed stocks are dependent on the availability of benthic source populations (continuous throughout the year) and export due to degradation (high in summer/fall) and stranding (high in summer).
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&amp;lt;p&amp;gt;The meridional modes (MM) in the Pacific are the conduit by which mid to high-latitudes external forcing (NPO/SPO) can trigger or influence ENSO; While for the Northern Hemisphere the MM (NPMM) is considered a... more
&amp;lt;p&amp;gt;The meridional modes (MM) in the Pacific are the conduit by which mid to high-latitudes external forcing (NPO/SPO) can trigger or influence ENSO; While for the Northern Hemisphere the MM (NPMM) is considered a precursor of ENSO, the MM-ENSO relationship in the Southern Hemisphere (SH) is more uncertain. Here we show that, rather than acting as a precursor, strong MMs of the SH (SPMM) are dominantly (~66%) triggered by strong El Ni&amp;amp;#241;o events in observations and the historical simulations of the Large Ensemble CESM (LENS-CESM). In the LENS-CESM simulations, strong ENSO-induced SPMMs are associated with a precursor signal (warm SST anomalies) of the coast off northern central Chile (20&amp;amp;#176;S-35&amp;amp;#176;S) resulting from the combined effect of the propagation of oceanic downwelling coastal Kelvin waves and the reduction in upwelling favorable winds due to an activated Pacific South American (PSA) pattern during the development of coincident ENSO cycle. The analysis of the simulations of the Coupled Intercomparison Project phases 5 and 6 (CMIP5/6) indicate a large diversity in terms of the ENSO-SPMM relationship, which can be interpreted as resulting from the spread in the meridional location of the center of action of the SPMM and of the seasonality of the SPO variance. We further discuss how ENSO-induced SPMM interferes with the coincident ENSO cycle and contributes to its asymmetry.&amp;lt;/p&amp;gt;
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La distribucion y variabilidad de la Zona Minimo de Oxigeno (ZMO) localizada frente a Chile central esta fuertemente asociada a la variabilidad del Agua Ecuatorial Subsuperficial y a la surgencia costera desarrollada frente a Chile. A su... more
La distribucion y variabilidad de la Zona Minimo de Oxigeno (ZMO) localizada frente a Chile central esta fuertemente asociada a la variabilidad del Agua Ecuatorial Subsuperficial y a la surgencia costera desarrollada frente a Chile. A su vez, estos procesos estan relacionado con el transporte hacia el sur de la Corriente Subsuperficial Peru-Chile (CSPC) que fluye a lo largo del talud y plataforma continental de Chile. El objetivo de este estudio es documentar la variabilidad estacional del oxigeno disuelto (OD) entre 0-45 μ M frente a la costa central de Chile y analizar su relacion con la CSPC. Para este fin, se utiliza una simulacion numerica fisica-biogeoquimica de alta resolucion (1/12°) que acopla el modelo hidrodinamico ROMS con el modelo biogeoquimico BioEBUS. La validacion del modelo con observaciones in-situ y una base de datos climatologica (CARS-2009), indican una buena representacion de los principales aspectos de la variabilidad espacio-temporal de la region de estudio....
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In addition to being one of the most productive upwelling systems, the oceanic region off Peru is embedded in one of the most extensive Oxygen Minimum Zones (OMZs) of the world ocean. The dynamics of the OMZ off Peru remain uncertain,... more
In addition to being one of the most productive upwelling systems, the oceanic region off Peru is embedded in one of the most extensive Oxygen Minimum Zones (OMZs) of the world ocean. The dynamics of the OMZ off Peru remain uncertain, partly due to the scarcity of data and to the ubiquitous role of mesoscale activity on the circulation and biogeochemistry. Here we use a high-resolution coupled physical/biogeochemical model simulation to investigate the seasonal variability of the OMZ off Peru. The focus is on characterizing the seasonal cycle in Dissolved…
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Eastern boundary upwelling systems are characterized by high productivity that often leads to subsurface hypoxia on the shelf. Mesoscale eddies are important, frequent, and persistent features of circulation in these regions, transporting... more
Eastern boundary upwelling systems are characterized by high productivity that often leads to subsurface hypoxia on the shelf. Mesoscale eddies are important, frequent, and persistent features of circulation in these regions, transporting physical, chemical and biological properties from shelves to the open ocean. In austral fall of 2011, during the Tara Oceans expedition, a subsurface layer (200–400 m) in which the concentration of oxygen was very low (< 2 μmol kg<sup>−1</sup> of O<sub>2</sub>) was observed in the eastern South Pacific, ~ 900 km offshore (30° S, 81° W). Satellite altimetry combined with CTD observations associated the local oxygen anomaly with an intrathermocline, anticyclonic, mesoscale eddy with a diameter of about 150 km. The eddy contained Equatorial Subsurface Water (ESSW) that at this latitude is normally restricted near the coast. Undersaturation (44 %) of nitrous oxide (N<sub>2</sub>O) and nitrite accumulation (> 0....
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Two physical mechanisms can contribute to coastal upwelling, offshore Ekman transport and Ekman pumping due to the cyclonic wind stress curl, mainly caused by the abrupt decrease in wind stress (drop-off) in a cross-shore band of 100 km.... more
Two physical mechanisms can contribute to coastal upwelling, offshore Ekman transport and Ekman pumping due to the cyclonic wind stress curl, mainly caused by the abrupt decrease in wind stress (drop-off) in a cross-shore band of 100 km. This wind drop-off is thought to be an ubiquitous feature in coastal upwelling systems and to regulate the relative contribution of both mechanisms. It has been poorly studied along the central-northern Chile region because of the lack in wind measurements along the shoreline and of the relatively low-resolution of the available atmospheric Reanalysis. Here, the seasonal variability in Ekman transport, Ekman pumping and their relative contribution to total upwelling along the central-northern Chile region (~ 30° S) is evaluated from a high-resolution atmospheric model simulation. As a first step, the simulation is validated from satellite observations, which indicates a proper representation of the spatial and temporal variability of the wind along ...
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The seasonal cycle of the depth of several isotherms representative of the main thermocline near the western coast of South America shows important semiannual and annual components. Annual thermocline oscillations are mainly related to... more
The seasonal cycle of the depth of several isotherms representative of the main thermocline near the western coast of South America shows important semiannual and annual components. Annual thermocline oscillations are mainly related to wind stress curl changes and, secondarily, to alongshore wind and the annual equatorial Kelvin wave. In contrast, the important semiannual component observed in hydrographic data off
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In this study, we quantify the annual and synoptic variability of solar radiation (PAR and UVR) for southern-central Chile at ∼36.5°S from 2003 to 2004 and we relate these fluctuations to total ozone concentration, cloudiness, and winds.... more
In this study, we quantify the annual and synoptic variability of solar radiation (PAR and UVR) for southern-central Chile at ∼36.5°S from 2003 to 2004 and we relate these fluctuations to total ozone concentration, cloudiness, and winds. Data considered approximately 2years of daily visible PAR (400–700nm), UVA (400–320nm), and UVB (280–320nm). Satellite ozone data were also compared with a 305/340
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During the1997-98 El Ni~no event, the tempera- ture and oxygen contents of the coastal waters o northern Chile were noticeably higher than during non-El Ni~no con- ditions, butphytoplanktonandzooplanktonbiomasses were not dramatically... more
During the1997-98 El Ni~no event, the tempera- ture and oxygen contents of the coastal waters o northern Chile were noticeably higher than during non-El Ni~no con- ditions, butphytoplanktonandzooplanktonbiomasses were not dramatically altered. In contrast, the herbivorous cope- pod Calanus chilensis, which showed a limited tolerance to low-oxygenconditions,exhibitedgreaterabundances,higher growth rates, and a signicant reduction in adult body size. These results indicate
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During the 1997-98 El Niño event, the temperature and oxygen contents of the coastal waters off northern Chile were noticeably higher than during non-El Niño conditions, but phytoplankton and zooplankton biomasses were not dramatically... more
During the 1997-98 El Niño event, the temperature and oxygen contents of the coastal waters off northern Chile were noticeably higher than during non-El Niño conditions, but phytoplankton and zooplankton biomasses were not dramatically altered. In contrast, the herbivorous copepod Calanus chilensis, which showed a limited tolerance to low-oxygen conditions, exhibited greater abundances, higher growth rates, and a significant reduction