A Multiplatform Experiment to Unravel Meso- and Submesoscale Processes in an Intense Front (AlborEx)

Pascual, Ananda; Ruiz, Simón; Olita, Antonio; Troupin, Charles; Claret, Mariona; Casas, Benjamín; Mourre, Baptiste; Poulain, Pierre‐Marie; Tovar-Sánchez, Antonio; Capet, Arthur; Mason, Evan; Allen, John T.; Mahadevan, Amala; Tintoré, Joaquı́n

doi:10.3389/fmars.2017.00039

Cited by 85 publications

(89 citation statements)

References 71 publications

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“…In order to reduce these uncertainties it is crucial to evaluate how eddy‐pump induced export interacts with other biological pump mechanisms such as sinking of particles (Boyd & Trull, ) or the mixed‐layer pump (Dall'Olmo et al, ). Multidisciplinary approaches will be needed to combine biogeochemical measurements with high‐resolution satellite altimetry (SWOT) and ship‐based lagrangian sampling strategies (Pascual et al, ; Petrenko et al, ). In this regard, projects such as GOCART (http://projects.noc.ac.uk/gocart/), COMICS (Sanders et al, ) or EXPORTS (Siegel et al, ) will provide excellent frameworks to quantify the different processes involved, but the BGCArgo network will still be critical to extrapolate these results to climate‐relevant scales.…”

Section: Discussionmentioning

confidence: 99%

Evaluating Southern Ocean Carbon Eddy‐Pump From Biogeochemical‐Argo Floats

et al. 2018

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The vertical transport of surface water and carbon into ocean's interior, known as subduction, is one of the main mechanisms through which the ocean influences Earth's climate. New instrumental approaches have shown the occurrence of localized and intermittent subduction episodes associated with small‐scale ocean circulation features. These studies also revealed the importance of such events for the export of organic matter, the so‐called eddy‐pump. However, the transient and localized nature of episodic subduction hindered its large‐scale evaluation to date. In this work, we present an approach to detect subduction events at the scale of the Southern Ocean using measurements collected by biogeochemical autonomous floats (BGCArgo). We show how subduction events can be automatically identified as anomalies of spiciness and Apparent Oxygen Utilization (AOU) below the mixed layer. Using this methodology over more than 4,000 profiles, we detected 40 subduction events unevenly distributed across the Sothern Ocean. Events were more likely found in hot spots of eddy kinetic energy (EKE), downstream major bathymetric features. Moreover, the bio‐optical measurements provided by BGCArgo allowed measuring the amount of Particulate Organic Carbon (POC) being subducted and assessing the contribution of these events to the total downward carbon flux at 100 m (EP100). We estimated that the eddy‐pump represents less than 19% to the EP100 in the Southern Ocean, although we observed particularly strong events able to locally duplicate the EP100. This approach provides a novel perspective on where episodic subduction occurs that will be naturally improved as BGCArgo observations continue to increase.

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Section: Discussionmentioning

confidence: 99%

Evaluating Southern Ocean Carbon Eddy‐Pump From Biogeochemical‐Argo Floats

et al. 2018

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“…Data from multiplatform experiments such as PUMP can play an important role in the assessment of operational products such as those provided by CMEMS, and we expect to see more examples in the future as the need for and benefit of these types of experiments becomes apparent (Shcherbina et al, 2015;Pascual et al, 2017).…”

Section: Discussion and Concluding Remarksmentioning

confidence: 99%

Comparing a Multivariate Global Ocean State Estimate With High-Resolution in Situ Data: An Anticyclonic Intrathermocline Eddy Near the Canary Islands

et al. 2018

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The provision of high-resolution in situ oceanographic data is key for the ongoing verification, validation and assessment of operational products, such as those provided by the Copernicus Marine Core Service (CMEMS). Here we analyze the ability of ARMOR3D-a multivariate global ocean state estimate that is available from CMEMS-to reconstruct a mesoscale anticyclonic intrathermocline eddy that was previously sampled with high-resolution independent in situ observations. ARMOR3D is constructed by merging remote sensing observations with in situ vertical profiles of temperature and salinity obtained primarily from the Argo network. In situ data from CTDs and an Acoustic Doppler Current Profiler were obtained during an oceanographic cruise near the Canary Islands (Atlantic ocean). The analysis of the ARMOR3D product using the in situ data is done over (i) a high-resolution meridional transect crossing the eddy center and (ii) a three-dimensional grid centered on the eddy center. An evaluation of the hydrographic eddy signature and derived dynamical variables, namely geostrophic velocity, vertical vorticity and quasi-geostrophic (QG) vertical velocity, demonstrates that the ARMOR3D product is able to reproduce the vertical hydrographic structure of the independently sampled eddy below the seasonal pycnocline, with the caveat that the flow is surface intensified and the seasonal pycnocline remains flat. Maps of ARMOR3D density show the signature of the eddy, and agreement with the elliptical eddy shape seen in the in situ data. The major eddy axes are oriented NW-SE in both data sets. The estimated radius for the in situ eddy is ∼46 km; the ARMOR3D radius is significantly larger at ∼ 92 km and is considered an overestimation that is inherited from an across-track altimetry sampling issue. The ARMOR3D geostrophic flow is underestimated by a factor of 2, with maxima of 0.11 (−0.19) m s −1 at the surface, which implies an underestimation of the local Rossby number by a factor of 3. Both the in situ and ARMOR3D eddies have decelerating flows at their northern edges. The ARMOR3D QG vertical velocity distribution has upwelling/downwelling cells located along the eddy periphery and similar magnitudes to the in situ-derived QG vertical velocity.

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“…The efficient study of submesoscale structures and their associated physical-biological-biogeochemical mechanisms requires the use of a combination of several complementary approaches involving in-situ observations and sampling, remote-sensing and model simulations (Pascual et al, 2017). High-resolution measurements are mandatory to assess the mechanisms controlling the fine-scale biophysical interactions.…”

Section: General Surface Circulation Pattern In the Western Basin Of mentioning

confidence: 99%

“…The Mediterranean Sea is a reduced-scale laboratory basin for the investigation of processes of global importance (Malanotte-Rizzoli et al, 2014;Pascual et al, 2017) because it is 20 characterized by a complex circulation scheme including deep water formation and intense mesoscale and submesoscale variability (Millot and Taupier-Letage, 2005). Mesoscale and submesoscale variability overlays and interacts with the basin and sub-basin scales, producing intricate processes representative of a complex and still unresolved oceanic systems (Malanotte-Rizzoli et al, 2014;Pascual et al, 2017). The small size of the Mediterranean Sea and the proximity of numerous marine observatories are other outstanding advantages giving 25 its status of 'miniature ocean' laboratory.…”

Section: Introductionmentioning

confidence: 99%

Coupling physics and biogeochemistry thanks to high resolution observations of the phytoplankton community structure in the North-Western Mediterranean Sea

Marrec¹,

Doglioli²,

Grégori³

et al. 2017

Preprint

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Abstract. Fine-scale physical structures and ocean dynamics strongly influence and regulate biogeochemical and ecological processes. These processes are particularly challenging to describe and understand because of their ephemeral nature. The OSCAHR (Observing Submesoscale Coupling At High Resolution) campaign has been conducted in fall 2015 in which, a fine-scale structure in the North Western Mediterranean Ligurian subbasin 15 was pre-identified using both satellite and numerical modeling data. Along the ship track, various variables were measured at the surface (temperature, salinity, chlorophyll-a and nutrients concentrations) with ADCP current velocity. We also deployed a new model of CytoSense automated flow cytometer (AFCM) optimized for small and dim cells, for near real-time characterization of surface phytoplankton community structure of surface waters with a spatial resolution of few km and a hourly temporal resolution. For the first time with this type of AFCM 20 we were able to resolve Prochlorococcus and Synechococcus picocyanobacteria. The vertical physical dynamics and biogeochemical properties of the studied area were investigated by continuous high resolution CTD profiles thanks to a moving vessel profiler (MVP) during the vessel underway associated to a 1-m vertical resolution pumping system deployed during fixed stations. The observed fine-scale feature presented a cyclonic structure with a relatively cold core surrounded by warmer waters. Surface waters were totally depleted in nitrate and 25 phosphate. In addition to the doming of the isopycnals by the cyclonic circulation, an intense wind event inducedEkman pumping. The upwelled subsurface cold nutrient-rich water fertilized surface waters, characterized by an increase in Chl-a concentration. Prochlorococcus, pico-and nano-eukaryotes were more abundant in cold core waters while Synechococcus dominated in warm boundary waters. Nanoeukaryote were the main contributors

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A Multiplatform Experiment to Unravel Meso- and Submesoscale Processes in an Intense Front (AlborEx)

Cited by 85 publications

References 71 publications

Evaluating Southern Ocean Carbon Eddy‐Pump From Biogeochemical‐Argo Floats

Evaluating Southern Ocean Carbon Eddy‐Pump From Biogeochemical‐Argo Floats

Comparing a Multivariate Global Ocean State Estimate With High-Resolution in Situ Data: An Anticyclonic Intrathermocline Eddy Near the Canary Islands

Coupling physics and biogeochemistry thanks to high resolution observations of the phytoplankton community structure in the North-Western Mediterranean Sea

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