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Gilles
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ArticleSatellite and in situ salinity : understanding near-surface stratification and subfootprint variability(American Meteorological Society, 2016-08-31) Boutin, Jacqueline ; Chao, Yi ; Asher, William E. ; Delcroix, Thierry ; Drucker, Robert S. ; Drushka, Kyla ; Kolodziejczyk, Nicolas ; Lee, Tong ; Reul, Nicolas ; Reverdin, Gilles ; Schanze, Julian J. ; Soloviev, Alexander ; Yu, Lisan ; Anderson, Jessica ; Brucker, Ludovic ; Dinnat, Emmanuel ; Santos-Garcia, Andrea ; Jones, W. Linwood ; Maes, Christophe ; Meissner, Thomas ; Tang, Wenqing ; Vinogradova, Nadya ; Ward, BrianRemote sensing of salinity using satellite-mounted microwave radiometers provides new perspectives for studying ocean dynamics and the global hydrological cycle. Calibration and validation of these measurements is challenging because satellite and in situ methods measure salinity differently. Microwave radiometers measure the salinity in the top few centimeters of the ocean, whereas most in situ observations are reported below a depth of a few meters. Additionally, satellites measure salinity as a spatial average over an area of about 100 × 100 km2. In contrast, in situ sensors provide pointwise measurements at the location of the sensor. Thus, the presence of vertical gradients in, and horizontal variability of, sea surface salinity complicates comparison of satellite and in situ measurements. This paper synthesizes present knowledge of the magnitude and the processes that contribute to the formation and evolution of vertical and horizontal variability in near-surface salinity. Rainfall, freshwater plumes, and evaporation can generate vertical gradients of salinity, and in some cases these gradients can be large enough to affect validation of satellite measurements. Similarly, mesoscale to submesoscale processes can lead to horizontal variability that can also affect comparisons of satellite data to in situ data. Comparisons between satellite and in situ salinity measurements must take into account both vertical stratification and horizontal variability.
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ArticleEditorial: Oceanobs19: An ocean of opportunity(Frontiers Media, 2019-09-06) Speich, Sabrina ; Lee, Tong ; Muller-Karger, Frank E. ; Lorenzoni, Laura ; Pascual, Ananda ; Jin, Di ; Delory, Eric ; Reverdin, Gilles ; Siddorn, John ; Lewis, Marlon R. ; Marba, Nuria ; Buttigieg, Pier Luigi ; Chiba, Sanae ; Manley, Justin ; Kabo-Bah, Amos Tiereyangn ; Desai, Kruti ; Ackerman, AbbyThe OceanObs conferences are held once every 10 years for the scientific, technical, and operational communities involved in the planning, implementation, and use of ocean observing systems. They serve to communicate progress, promote plans, and to define advances in ocean observing in response to societies' needs. Each conference provides a forum for the community to review the state of the ocean observing science and operations, and to define goals and plans to achieve over the next decade.
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PreprintSurprising return of deep convection to the subpolar North Atlantic Ocean in winter 2007–2008( 2008-11-07) Våge, Kjetil ; Pickart, Robert S. ; Thierry, Virginie ; Reverdin, Gilles ; Lee, Craig M. ; Petrie, Brian ; Agnew, Tom A. ; Wong, Amy ; Ribergaard, Mads H.The process of open-ocean convection in the subpolar North Atlantic Ocean forms a dense water mass that impacts the meridional overturning circulation and heat flux, and sequesters atmospheric carbon. In recent years the convection has been shallow or nonexistent, which could be construed as a consequence of a warmer climate. However, in the winter of 2007-08 deep convection returned to the subpolar gyre in both the Labrador and Irminger Seas. Here we document this return and elucidate the reasons why it happened. Profiling float data from the Argo programme are used to document the deep mixing, and a variety of in-situ, satellite, and reanalysis products are analyzed to describe the conditions leading to the overturning. The transition to a convective state took place abruptly, without going through a preconditioning phase, which is contrary to general expectations. Changes in the hemispheric air temperature, tracks of storms, flux of freshwater to the Labrador Sea, and distribution of pack ice all conspired to enhance the air-sea heat flux, resulting in the deep overturning. This study illuminates the complexity of the North Atlantic convective system.
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ArticleAtlantic climate variability and predictability : a CLIVAR perspective(American Meteorological Society, 2006-10-15) Hurrell, James W. ; Visbeck, Martin ; Busalacchi, Antonio J. ; Clarke, R. A. ; Delworth, T. L. ; Dickson, R. R. ; Johns, William E. ; Koltermann, K. P. ; Kushnir, Yochanan ; Marshall, David P. ; Mauritzen, Cecilie ; McCartney, Michael S. ; Piola, Alberto R. ; Reason, C. ; Reverdin, Gilles ; Schott, F. ; Sutton, R. ; Wainer, I. ; Wright, Daniel G.Three interrelated climate phenomena are at the center of the Climate Variability and Predictability (CLIVAR) Atlantic research: tropical Atlantic variability (TAV), the North Atlantic Oscillation (NAO), and the Atlantic meridional overturning circulation (MOC). These phenomena produce a myriad of impacts on society and the environment on seasonal, interannual, and longer time scales through variability manifest as coherent fluctuations in ocean and land temperature, rainfall, and extreme events. Improved understanding of this variability is essential for assessing the likely range of future climate fluctuations and the extent to which they may be predictable, as well as understanding the potential impact of human-induced climate change. CLIVAR is addressing these issues through prioritized and integrated plans for short-term and sustained observations, basin-scale reanalysis, and modeling and theoretical investigations of the coupled Atlantic climate system and its links to remote regions. In this paper, a brief review of the state of understanding of Atlantic climate variability and achievements to date is provided. Considerable discussion is given to future challenges related to building and sustaining observing systems, developing synthesis strategies to support understanding and attribution of observed change, understanding sources of predictability, and developing prediction systems in order to meet the scientific objectives of the CLIVAR Atlantic program.
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ArticleExpanding Tara oceans protocols for underway, ecosystemic sampling of the ocean-atmosphere interface during Tara Pacific expedition (2016-2018)(Frontiers Media, 2019-12-11) Gorsky, Gabriel ; Bourdin, Guillaume ; Lombard, Fabien ; Pedrotti, Maria Luiza ; Audrain, Samuel ; Bin, Nicolas ; Boss, Emmanuel S. ; Bowler, Chris ; Cassar, Nicolas ; Caudan, Loic ; Chabot, Genevieve ; Cohen, Natalie R. ; Cron, Daniel ; De Vargas, Colomban ; Dolan, John R. ; Douville, Eric ; Elineau, Amanda ; Flores, J. Michel ; Ghiglione, Jean-Francois ; Haëntjens, Nils ; Hertau, Martin ; John, Seth G. ; Kelly, Rachel L. ; Koren, Ilan ; Lin, Yajuan ; Marie, Dominique ; Moulin, Clémentine ; Moucherie, Yohann ; Pesant, Stephane ; Picheral, Marc ; Poulain, Julie ; Pujo-Pay, Mireille ; Reverdin, Gilles ; Romac, Sarah ; Sullivan, Mathew B. ; Trainic, Miri ; Tressol, Marc ; Troublé, Romain ; Vardi, Assaf ; Voolstra, Christian R. ; Wincker, Patrick ; Agostini, Sylvain ; Banaigs, Bernard ; Boissin, Emilie ; Forcioli, Didier ; Furla, Paola ; Galand, Pierre E. ; Gilson, Eric ; Reynaud, Stephanie ; Sunagawa, Shinichi ; Thomas, Olivier P. ; Vega Thurber, Rebecca ; Zoccola, Didier ; Planes, Serge ; Allemand, Denis ; Karsenti, EricInteractions between the ocean and the atmosphere occur at the air-sea interface through the transfer of momentum, heat, gases and particulate matter, and through the impact of the upper-ocean biology on the composition and radiative properties of this boundary layer. The Tara Pacific expedition, launched in May 2016 aboard the schooner Tara, was a 29-month exploration with the dual goals to study the ecology of reef ecosystems along ecological gradients in the Pacific Ocean and to assess inter-island and open ocean surface plankton and neuston community structures. In addition, key atmospheric properties were measured to study links between the two boundary layer properties. A major challenge for the open ocean sampling was the lack of ship-time available for work at “stations”. The time constraint led us to develop new underway sampling approaches to optimize physical, chemical, optical, and genomic methods to capture the entire community structure of the surface layers, from viruses to metazoans in their oceanographic and atmospheric physicochemical context. An international scientific consortium was put together to analyze the samples, generate data, and develop datasets in coherence with the existing Tara Oceans database. Beyond adapting the extensive Tara Oceans sampling protocols for high-resolution underway sampling, the key novelties compared to Tara Oceans’ global assessment of plankton include the measurement of (i) surface plankton and neuston biogeography and functional diversity; (ii) bioactive trace metals distribution at the ocean surface and metal-dependent ecosystem structures; (iii) marine aerosols, including biological entities; (iv) geography, nature and colonization of microplastic; and (v) high-resolution underway assessment of net community production via equilibrator inlet mass spectrometry. We are committed to share the data collected during this expedition, making it an important resource important resource to address a variety of scientific questions.
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ArticleImproved statistical method for quality control of hydrographic observations(American Meteorological Society, 2020-05-04) Gourrion, Jérôme ; Szekely, Tanguy ; Killick, Rachel E. ; Owens, W. Brechner ; Reverdin, Gilles ; Charpon, BertrandRealistic ocean state prediction and its validation rely on the availability of high quality in situ observations. To detect data errors, adequate quality check procedures must be designed. This paper presents procedures that take advantage of the ever-growing observation databases that provide climatological knowledge of the ocean variability in the neighborhood of an observation location. Local validity intervals are used to estimate binarily whether the observed values are considered as good or erroneous. Whereas a classical approach estimates validity bounds from first- and second-order moments of the climatological parameter distribution, that is, mean and variance, this work proposes to infer them directly from minimum and maximum observed values. Such an approach avoids any assumption of the parameter distribution such as unimodality, symmetry around the mean, peakedness, or homogeneous distribution tail height relative to distribution peak. To reach adequate statistical robustness, an extensive manual quality control of the reference dataset is critical. Once the data have been quality checked, the local minima and maxima reference fields are derived and the method is compared with the classical mean/variance-based approach. Performance is assessed in terms of statistics of good and bad detections. It is shown that the present size of the reference datasets allows the parameter estimates to reach a satisfactory robustness level to always make the method more efficient than the classical one. As expected, insufficient robustness persists in areas with an especially low number of samples and high variability.
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ArticleGlobal in situ observations of essential climate and ocean variables at the air-sea interface(Frontiers Media, 2019-07-25) Centurioni, Luca R. ; Turton, Jon ; Lumpkin, Rick ; Braasch, Lancelot ; Brassington, Gary ; Chao, Yi ; Charpentier, Etienne ; Chen, Zhaohui ; Corlett, Gary ; Dohan, Kathleen ; Donlon, Craig ; Gallage, Champika ; Hormann, Verena ; Ignatov, Alexander ; Ingleby, Bruce ; Jensen, Robert ; Kelly-Gerreyn, Boris A. ; Koszalka, Inga M. ; Lin, Xiaopei ; Lindstrom, Eric ; Maximenko, Nikolai ; Merchant, Christopher J. ; Minnett, Peter J. ; O’Carroll, Anne ; Paluszkiewicz, Theresa ; Poli, Paul ; Poulain, Pierre Marie ; Reverdin, Gilles ; Sun, Xiujun ; Swail, Val ; Thurston, Sidney ; Wu, Lixin ; Yu, Lisan ; Wang, Bin ; Zhang, DongxiaoThe air–sea interface is a key gateway in the Earth system. It is where the atmosphere sets the ocean in motion, climate/weather-relevant air–sea processes occur, and pollutants (i.e., plastic, anthropogenic carbon dioxide, radioactive/chemical waste) enter the sea. Hence, accurate estimates and forecasts of physical and biogeochemical processes at this interface are critical for sustainable blue economy planning, growth, and disaster mitigation. Such estimates and forecasts rely on accurate and integrated in situ and satellite surface observations. High-impact uses of ocean surface observations of essential ocean/climate variables (EOVs/ECVs) include (1) assimilation into/validation of weather, ocean, and climate forecast models to improve their skill, impact, and value; (2) ocean physics studies (i.e., heat, momentum, freshwater, and biogeochemical air–sea fluxes) to further our understanding and parameterization of air–sea processes; and (3) calibration and validation of satellite ocean products (i.e., currents, temperature, salinity, sea level, ocean color, wind, and waves). We review strengths and limitations, impacts, and sustainability of in situ ocean surface observations of several ECVs and EOVs. We draw a 10-year vision of the global ocean surface observing network for improved synergy and integration with other observing systems (e.g., satellites), for modeling/forecast efforts, and for a better ocean observing governance. The context is both the applications listed above and the guidelines of frameworks such as the Global Ocean Observing System (GOOS) and Global Climate Observing System (GCOS) (both co-sponsored by the Intergovernmental Oceanographic Commission of UNESCO, IOC–UNESCO; the World Meteorological Organization, WMO; the United Nations Environment Programme, UNEP; and the International Science Council, ISC). Networks of multiparametric platforms, such as the global drifter array, offer opportunities for new and improved in situ observations. Advances in sensor technology (e.g., low-cost wave sensors), high-throughput communications, evolving cyberinfrastructures, and data information systems with potential to improve the scope, efficiency, integration, and sustainability of the ocean surface observing system are explored.
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ArticleEUREC4A(Copernicus Publications, 2021-08-25) Stevens, Bjorn ; Bony, Sandrine ; Farrell, David ; Ament, Felix ; Blyth, Alan ; Fairall, Christopher W. ; Karstensen, Johannes ; Quinn, Patricia K. ; Speich, Sabrina ; Acquistapace, Claudia ; Aemisegger, Franziska ; Albright, Anna Lea ; Bellenger, Hugo ; Bodenschatz, Eberhard ; Caesar, Kathy-Ann ; Chewitt-Lucas, Rebecca ; de Boer, Gijs ; Delanoë, Julien ; Denby, Leif ; Ewald, Florian ; Fildier, Benjamin ; Forde, Marvin ; George, Geet ; Gross, Silke ; Hagen, Martin ; Hausold, Andrea ; Heywood, Karen J. ; Hirsch, Lutz ; Jacob, Marek ; Jansen, Friedhelm ; Kinne, Stefan ; Klocke, Daniel ; Kölling, Tobias ; Konow, Heike ; Lothon, Marie ; Mohr, Wiebke ; Naumann, Ann Kristin ; Nuijens, Louise ; Olivier, Léa ; Pincus, Robert ; Pöhlker, Mira L. ; Reverdin, Gilles ; Roberts, Gregory ; Schnitt, Sabrina ; Schulz, Hauke ; Siebesma, Pier ; Stephan, Claudia Christine ; Sullivan, Peter P. ; Touzé-Peiffer, Ludovic ; Vial, Jessica ; Vogel, Raphaela ; Zuidema, Paquita ; Alexander, Nicola ; Alves, Lyndon ; Arixi, Sophian ; Asmath, Hamish ; Bagheri, Gholamhossein ; Baier, Katharina ; Bailey, Adriana ; Baranowski, Dariusz ; Baron, Alexandre ; Barrau, Sébastien ; Barrett, Paul A. ; Batier, Frédéric ; Behrendt, Andreas ; Bendinger, Arne ; Beucher, Florent ; Bigorre, Sebastien P. ; Blades, Edmund ; Blossey, Peter ; Bock, Olivier ; Böing, Steven ; Bosser, Pierre ; Bourras, Denis ; Bouruet-Aubertot, Pascale ; Bower, Keith ; Branellec, Pierre ; Branger, Hubert ; Brennek, Michal ; Brewer, Alan ; Brilouet, Pierre-Etienne ; Brügmann, Björn ; Buehler, Stefan A. ; Burke, Elmo ; Burton, Ralph ; Calmer, Radiance ; Canonici, Jean-Christophe ; Carton, Xavier ; Cato, Gregory, Jr. ; Charles, Jude Andre ; Chazette, Patrick ; Chen, Yanxu ; Chilinski, Michal T. ; Choularton, Thomas ; Chuang, Patrick ; Clarke, Shamal ; Coe, Hugh ; Cornet, Céline ; Coutris, Pierre ; Couvreux, Fleur ; Crewell, Susanne ; Cronin, Timothy W. ; Cui, Zhiqiang ; Cuypers, Yannis ; Daley, Alton ; Damerell, Gillian M. ; Dauhut, Thibaut ; Deneke, Hartwig ; Desbios, Jean-Philippe ; Dörner, Steffen ; Donner, Sebastian ; Douet, Vincent ; Drushka, Kyla ; Dütsch, Marina ; Ehrlich, André ; Emanuel, Kerry A. ; Emmanouilidis, Alexandros ; Etienne, Jean-Claude ; Etienne-Leblanc, Sheryl ; Faure, Ghislain ; Feingold, Graham ; Ferrero, Luca ; Fix, Andreas ; Flamant, Cyrille ; Flatau, Piotr Jacek ; Foltz, Gregory R. ; Forster, Linda ; Furtuna, Iulian ; Gadian, Alan ; Galewsky, Joseph ; Gallagher, Martin ; Gallimore, Peter ; Gaston, Cassandra J. ; Gentemann, Chelle L. ; Geyskens, Nicolas ; Giez, Andreas ; Gollop, John ; Gouirand, Isabelle ; Gourbeyre, Christophe ; de Graaf, Dörte ; de Graaf, Geiske E. ; Grosz, Robert ; Güttler, Johannes ; Gutleben, Manuel ; Hall, Kashawn ; Harris, George ; Helfer, Kevin C. ; Henze, Dean ; Herbert, Calvert ; Holanda, Bruna ; Ibanez-Landeta, Antonio ; Intrieri, Janet ; Iyer, Suneil ; Julien, Fabrice ; Kalesse, Heike ; Kazil, Jan ; Kellman, Alexander ; Kidane, Abiel T. ; Kirchner, Ulrike ; Klingebiel, Marcus ; Körner, Mareike ; Kremper, Leslie Ann ; Kretzschmar, Jan ; Krüger, Ovid O. ; Kumala, Wojciech ; Kurz, Armin ; L'Hégareta, Pierre ; Labaste, Matthieu ; Lachlan-Cope, Thomas ; Laing, Arlene ; Landschützer, Peter ; Lang, Theresa ; Lange, Diego ; Lange, Ingo ; Laplace, Clément ; Lavik, Gauke ; Laxenaire, Rémi ; Le Bihan, Caroline ; Leandro, Mason ; Lefevre, Nathalie ; Lena, Marius ; Lenschow, Donald ; Li, Qiang ; Lloyd, Gary ; Los, Sebastian ; Losi, Niccolò ; Lovell, Oscar ; Luneau, Christopher ; Makuch, Przemyslaw ; Malinowski, Szymon ; Manta, Gaston ; Marinou, Eleni ; Marsden, Nicholas ; Masson, Sebastien ; Maury, Nicolas ; Mayer, Bernhard ; Mayers-Als, Margarette ; Mazel, Christophe ; McGeary, Wayne ; McWilliams, James C. ; Mech, Mario ; Mehlmann, Melina ; Meroni, Agostino Niyonkuru ; Mieslinger, Theresa ; Minikin, Andreas ; Minnett, Peter J. ; Möller, Gregor ; Morfa Avalos, Yanmichel ; Muller, Caroline ; Musat, Ionela ; Napoli, Anna ; Neuberger, Almuth ; Noisel, Christophe ; Noone, David ; Nordsiek, Freja ; Nowak, Jakub L. ; Oswald, Lothar ; Parker, Douglas J. ; Peck, Carolyn ; Person, Renaud ; Philippi, Miriam ; Plueddemann, Albert J. ; Pöhlker, Christopher ; Pörtge, Veronika ; Pöschl, Ulrich ; Pologne, Lawrence ; Posyniak, Michał ; Prange, Marc ; Quinones Melendez, Estefania ; Radtke, Jule ; Ramage, Karim ; Reimann, Jens ; Renault, Lionel ; Reus, Klaus ; Reyes, Ashford ; Ribbe, Joachim ; Ringel, Maximilian ; Ritschel, Markus ; Rocha, Cesar B. ; Rochetin, Nicolas ; Röttenbacher, Johannes ; Rollo, Callum ; Royer, Haley M. ; Sadoulet, Pauline ; Saffin, Leo ; Sandiford, Sanola ; Sandu, Irina ; Schäfer, Michael ; Schemann, Vera ; Schirmacher, Imke ; Schlenczek, Oliver ; Schmidt, Jerome M. ; Schröder, Marcel ; Schwarzenboeck, Alfons ; Sealy, Andrea ; Senff, Christoph J. ; Serikov, Ilya ; Shohan, Samkeyat ; Siddle, Elizabeth ; Smirnov, Alexander ; Späth, Florian ; Spooner, Branden ; Stolla, M. Katharina ; Szkółka, Wojciech ; de Szoeke, Simon P. ; Tarot, Stéphane ; Tetoni, Eleni ; Thompson, Elizabeth ; Thomson, Jim ; Tomassini, Lorenzo ; Totems, Julien ; Ubele, Alma Anna ; Villiger, Leonie ; von Arx, Jan ; Wagner, Thomas ; Walther, Andi ; Webber, Ben ; Wendisch, Manfred ; Whitehall, Shanice ; Wiltshire, Anton ; Wing, Allison A. ; Wirth, Martin ; Wiskandt, Jonathan ; Wolf, Kevin ; Worbes, Ludwig ; Wright, Ethan ; Young, Shanea ; Zhang, Chidong ; Zhang, Dongxiao ; Ziemen, Florian ; Zinner, Tobias ; Zöger, MartinThe science guiding the EUREC4A campaign and its measurements is presented. EUREC4A comprised roughly 5 weeks of measurements in the downstream winter trades of the North Atlantic – eastward and southeastward of Barbados. Through its ability to characterize processes operating across a wide range of scales, EUREC4A marked a turning point in our ability to observationally study factors influencing clouds in the trades, how they will respond to warming, and their link to other components of the earth system, such as upper-ocean processes or the life cycle of particulate matter. This characterization was made possible by thousands (2500) of sondes distributed to measure circulations on meso- (200 km) and larger (500 km) scales, roughly 400 h of flight time by four heavily instrumented research aircraft; four global-class research vessels; an advanced ground-based cloud observatory; scores of autonomous observing platforms operating in the upper ocean (nearly 10 000 profiles), lower atmosphere (continuous profiling), and along the air–sea interface; a network of water stable isotopologue measurements; targeted tasking of satellite remote sensing; and modeling with a new generation of weather and climate models. In addition to providing an outline of the novel measurements and their composition into a unified and coordinated campaign, the six distinct scientific facets that EUREC4A explored – from North Brazil Current rings to turbulence-induced clustering of cloud droplets and its influence on warm-rain formation – are presented along with an overview of EUREC4A's outreach activities, environmental impact, and guidelines for scientific practice. Track data for all platforms are standardized and accessible at https://doi.org/10.25326/165 (Stevens, 2021), and a film documenting the campaign is provided as a video supplement.