Riser Stephen C.

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Stephen C.
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The Argo Program : observing the global ocean with profiling floats

2009-06 , Roemmich, Dean , Johnson, Gregory C. , Riser, Stephen C. , Davis, Russ E. , Gilson, John , Owens, W. Brechner , Garzoli, Silvia L. , Schmid, Claudia , Ignaszewski, Mark

The Argo Program has created the first global array for observing the subsurface ocean. Argo arose from a compelling scientific need for climate-relevant ocean data; it was made possible by technology development and implemented through international collaboration. The float program and its data management system began with regional arrays in 1999, scaled up to global deployments by 2004, and achieved its target of 3000 active instruments in 2007. US Argo, supported by the National Oceanic and Atmospheric Administration and the Navy through the National Oceanographic Partnership Program, provides half of the floats in the international array, plus leadership in float technology, data management, data quality control, international coordination, and outreach. All Argo data are freely available without restriction, in real time and in research-quality forms. Uses of Argo data range from oceanographic research, climate research, and education, to operational applications in ocean data assimilation and seasonal-to-decadal prediction. Argo’s value grows as its data accumulate and their applications are better understood. Continuing advances in profiling float and sensor technologies open many exciting possibilities for Argo’s future, including expanding sampling into high latitudes and the deep ocean, improving near-surface sampling, and adding biogeochemical parameters.

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Article

Supercooled Southern Ocean waters

2020-10-09 , Haumann, F. Alexander , Moorman, Ruth , Riser, Stephen C. , Smedsrud, Lars H. , Maksym, Ted , Wong, Annie P. S. , Wilson, Earle A. , Drucker, Robert S. , Talley, Lynne D. , Johnson, Kenneth S. , Key, Robert M. , Sarmiento, Jorge L.

In cold polar waters, temperatures sometimes drop below the freezing point, a process referred to as supercooling. However, observational challenges in polar regions limit our understanding of the spatial and temporal extent of this phenomenon. We here provide observational evidence that supercooled waters are much more widespread in the seasonally ice‐covered Southern Ocean than previously reported. In 5.8% of all analyzed hydrographic profiles south of 55°S, we find temperatures below the surface freezing point (“potential” supercooling), and half of these have temperatures below the local freezing point (“in situ” supercooling). Their occurrence doubles when neglecting measurement uncertainties. We attribute deep coastal‐ocean supercooling to melting of Antarctic ice shelves and surface‐induced supercooling in the seasonal sea‐ice region to wintertime sea‐ice formation. The latter supercooling type can extend down to the permanent pycnocline due to convective sinking plumes—an important mechanism for vertical tracer transport and water‐mass structure in the polar ocean.

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Article

Argo data 1999-2019: two million temperature-salinity profiles and subsurface velocity observations from a global array of profiling floats.

2020-09-15 , Wong, Annie P. S. , Wijffels, Susan E. , Riser, Stephen C. , Pouliquen, Sylvie , Hosoda, Shigeki , Roemmich, Dean , Gilson, John , Johnson, Gregory C. , Martini, Kim I. , Murphy, David J. , Scanderbeg, Megan , Udaya Bhaskar, T. V. S. , Buck, Justin J. H. , Merceur, Frederic , Carval, Thierry , Maze, Guillaume , Cabanes, Cécile , André, Xavier , Poffa, Noé , Yashayaev, Igor , Barker, Paul M. , Guinehut, Stéphanie , Belbeoch, Mathieu , Ignaszewski, Mark , Baringer, Molly O. , Schmid, Claudia , Lyman, John , McTaggart, Kristene E. , Purkey, Sarah G. , Zilberman, Nathalie , Alkire, Matthew , Swift, Dana , Owens, W. Brechner , Jayne, Steven R. , Hersh, Cora , Robbins, Pelle E. , West-Mack, Deb , Bahr, Frank B. , Yoshida, Sachiko , Sutton, Philip J. H. , Cancouët, Romain , Coatanoan, Christine , Dobbler, Delphine , Garcia Juan, Andrea , Gourrion, Jérôme , Kolodziejczyk, Nicolas , Bernard, Vincent , Bourlès, Bernard , Claustre, Hervé , d’Ortenzio, Fabrizio , Le Reste, Serge , Le Traon, Pierre-Yves , Rannou, Jean-Philippe , Saout-Grit, Carole , Speich, Sabrina , Thierry, Virginie , Verbrugge, Nathalie , Angel-Benavides, Ingrid M. , Klein, Birgit , Notarstefano, Giulio , Poulain, Pierre Marie , Vélez-Belchí, Pedro , Suga, Toshio , Ando, Kentaro , Iwasaska, Naoto , Kobayashi, Taiyo , Masuda, Shuhei , Oka, Eitarou , Sato, Kanako , Nakamura, Tomoaki , Sato, Katsunari , Takatsuki, Yasushi , Yoshida, Takashi , Cowley, Rebecca , Lovell, Jenny L. , Oke, Peter , van Wijk, Esmee , Carse, Fiona , Donnelly, Matthew , Gould, W. John , Gowers, Katie , King, Brian A. , Loch, Stephen G. , Mowat, Mary , Turton, Jon , Pattabhi Rama Rao, Eluri , Ravichandran, M. , Freeland, Howard , Gaboury, Isabelle , Gilbert, Denis , Greenan, Blair J. W. , Ouellet, Mathieu , Ross, Tetjana , Tran, Anh , Dong, Mingmei , Liu, Zenghong , Xu, Jianping , Kang, KiRyong , Jo, HyeongJun , Kim, Sung-Dae , Park, Hyuk-Min

In the past two decades, the Argo Program has collected, processed, and distributed over two million vertical profiles of temperature and salinity from the upper two kilometers of the global ocean. A similar number of subsurface velocity observations near 1,000 dbar have also been collected. This paper recounts the history of the global Argo Program, from its aspiration arising out of the World Ocean Circulation Experiment, to the development and implementation of its instrumentation and telecommunication systems, and the various technical problems encountered. We describe the Argo data system and its quality control procedures, and the gradual changes in the vertical resolution and spatial coverage of Argo data from 1999 to 2019. The accuracies of the float data have been assessed by comparison with high-quality shipboard measurements, and are concluded to be 0.002°C for temperature, 2.4 dbar for pressure, and 0.01 PSS-78 for salinity, after delayed-mode adjustments. Finally, the challenges faced by the vision of an expanding Argo Program beyond 2020 are discussed.

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Article

The Argo Program : present and future

2017-06 , Jayne, Steven R. , Roemmich, Dean , Zilberman, Nathalie , Riser, Stephen C. , Johnson, Kenneth S. , Johnson, Gregory C. , Piotrowicz, Stephen R.

The Argo Program has revolutionized large-scale physical oceanography through its contributions to basic research, national and international climate assessment, education, and ocean state estimation and forecasting. This article discusses the present status of Argo and enhancements that are underway. Extensions of the array into seasonally ice-covered regions and marginal seas as well as increased numbers of floats along the equator and around western boundary current extensions have been proposed. In addition, conventional Argo floats, with their 2,000 m sampling limit, currently observe only the upper half of the open ocean volume. Recent advances in profiling float technology and in the accuracy and stability of float-mounted conductivity-temperature-depth sensors make it practical to obtain measurements to 6,000 m. The Deep Argo array will help observe and constrain the global budgets of heat content, freshwater, and steric sea level, as well as the full-depth ocean circulation. Finally, another extension to the Argo Program is the addition of a diverse set of chemical sensors to profiling floats in order to build a Biogeochemical-Argo array to understand the carbon cycle, the biological pump, and ocean acidification.

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Article

The technological, scientific, and sociological revolution of global subsurface ocean observing

2022-01-07 , Roemmich, Dean , Talley, Lynne D. , Zilberman, Nathalie , Osborne, Emily , Johnson, Kenneth S. , Barbero, Leticia , Bittig, Henry C. , Briggs, Nathan , Fassbender, Andrea J. , Johnson, Gregory C. , King, Brian A. , McDonagh, Elaine L. , Purkey, Sarah G. , Riser, Stephen C. , Suga, Toshio , Takeshita, Yuichiro , Thierry, Virginie , Wijffels, Susan E.

The complementary partnership of the Global Ocean Ship-based Hydrographic Investigations Program (GO-SHIP; https://www.go-ship.org/) and the Argo Program (https://argo.ucsd.edu) has been instrumental in providing sustained subsurface observations of the global ocean for over two decades. Since the late twentieth century, new clues into the ocean’s role in Earth’s climate system have revealed a need for sustained global ocean observations (e.g., Gould et al., 2013; Schmitt, 2018) and stimulated revolutionary technology advances needed to address the societal mandate. Together, the international GO-SHIP and Argo Program responded to this need, providing insight into the mean state and variability of the physics, biology, and chemistry of the ocean that led to advancements in fundamental science and monitoring of the state of Earth's climate.

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Article

Salinity and temperature balances at the SPURS central mooring during fall and winter

2015-03 , Farrar, J. Thomas , Rainville, Luc , Plueddemann, Albert J. , Kessler, William S. , Lee, Craig M. , Hodges, Benjamin A. , Schmitt, Raymond W. , Edson, James B. , Riser, Stephen C. , Eriksen, Charles C. , Fratantoni, David M.

One part of the Salinity Processes in the Upper-ocean Regional Study (SPURS) field campaign focused on understanding the physical processes affecting the evolution of upper-ocean salinity in the region of climatological maximum sea surface salinity in the subtropical North Atlantic (SPURS-1). An upper-ocean salinity budget provides a useful framework for increasing this understanding. The SPURS-1 program included a central heavily instrumented mooring for making accurate measurements of air-sea surface fluxes, as well as other moorings, Argo floats, and gliders that together formed a dense observational array. Data from this array are used to estimate terms in the upper-ocean salinity and heat budgets during the SPURS-1 campaign, with a focus on the first several months (October 2012 to February 2013) when the surface mixed layer was becoming deeper, fresher, and cooler. Specifically, we examine the salinity and temperature balances for an upper-ocean mixed layer, defined as the layer where the density is within 0.4 kg m–3 of its surface value. The gross features of the evolution of upper-ocean salinity and temperature during this fall/winter season are explained by a combination of evaporation and precipitation at the sea surface, horizontal transport of heat and salt by mixed-layer currents, and vertical entrainment of fresher, cooler fluid into the layer as it deepened. While all of these processes were important in the observed seasonal (fall) freshening at this location in the salinity-maximum region, the variability of salinity on monthly-to-intraseasonal time scales resulted primarily from horizontal advection.

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Article

Autonomous multi-platform observations during the Salinity Processes in the Upper-ocean Regional Study

2017-06 , Lindstrom, Eric , Shcherbina, Andrey Y. , Rainville, Luc , Farrar, J. Thomas , Centurioni, Luca R. , Dong, Shenfu , D'Asaro, Eric A. , Eriksen, Charles C. , Fratantoni, David M. , Hodges, Benjamin A. , Hormann, Verena , Kessler, William S. , Lee, Craig M. , Riser, Stephen C. , St. Laurent, Louis C. , Volkov, Denis L.

The Salinity Processes in the Upper-ocean Regional Study (SPURS) aims to understand the patterns and variability of sea surface salinity. In order to capture the wide range of spatial and temporal scales associated with processes controlling salinity in the upper ocean, research vessels delivered autonomous instruments to remote sites, one in the North Atlantic and one in the Eastern Pacific. Instruments sampled for one complete annual cycle at each of these two sites, which are subject to contrasting atmospheric forcing. The SPURS field programs coordinated sampling from many different platforms, using a mix of Lagrangian and Eulerian approaches. This article discusses the motivations, implementation, and first results of the SPURS-1 and SPURS-2 programs.

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Article

Northern Arabian Sea Circulation-Autonomous Research (NASCar) : a research initiative based on autonomous sensors

2017-06 , Centurioni, Luca R. , Hormann, Verena , Talley, Lynne D. , Arzeno, Isabella B. , Beal, Lisa M. , Caruso, Michael J. , Conry, Patrick , Echols, Rosalind , Fernando, Harindra J. S. , Giddings, Sarah N. , Gordon, Arnold L. , Graber, Hans C. , Harcourt, Ramsey R. , Jayne, Steven R. , Jensen, Tommy G. , Lee, Craig M. , Lermusiaux, Pierre F. J. , L’Hegaret, Pierre , Lucas, Andrew J. , Mahadevan, Amala , McClean, Julie L. , Pawlak, Geno , Rainville, Luc , Riser, Stephen C. , Seo, Hyodae , Shcherbina, Andrey Y. , Skyllingstad, Eric D. , Sprintall, Janet , Subrahmanyam, Bulusu , Terrill, Eric , Todd, Robert E. , Trott, Corinne , Ulloa, Hugo N. , Wang, He

The Arabian Sea circulation is forced by strong monsoonal winds and is characterized by vigorous seasonally reversing currents, extreme differences in sea surface salinity, localized substantial upwelling, and widespread submesoscale thermohaline structures. Its complicated sea surface temperature patterns are important for the onset and evolution of the Asian monsoon. This article describes a program that aims to elucidate the role of upper-ocean processes and atmospheric feedbacks in setting the sea surface temperature properties of the region. The wide range of spatial and temporal scales and the difficulty of accessing much of the region with ships due to piracy motivated a novel approach based on state-of-the-art autonomous ocean sensors and platforms. The extensive data set that is being collected, combined with numerical models and remote sensing data, confirms the role of planetary waves in the reversal of the Somali Current system. These data also document the fast response of the upper equatorial ocean to monsoon winds through changes in temperature and salinity and the connectivity of the surface currents across the northern Indian Ocean. New observations of thermohaline interleaving structures and mixing in setting the surface temperature properties of the northern Arabian Sea are also discussed.

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Article

On the future of Argo: A global, full-depth, multi-disciplinary array

2019-08-02 , Roemmich, Dean , Alford, Matthew H. , Claustre, Hervé , Johnson, Kenneth S. , King, Brian , Moum, James N. , Oke, Peter , Owens, W. Brechner , Pouliquen, Sylvie , Purkey, Sarah G. , Scanderbeg, Megan , Suga, Koushirou , Wijffels, Susan E. , Zilberman, Nathalie , Bakker, Dorothee , Baringer, Molly O. , Belbeoch, Mathieu , Bittig, Henry C. , Boss, Emmanuel S. , Calil, Paulo H. R. , Carse, Fiona , Carval, Thierry , Chai, Fei , Conchubhair, Diarmuid Ó. , d’Ortenzio, Fabrizio , Dall'Olmo, Giorgio , Desbruyeres, Damien , Fennel, Katja , Fer, Ilker , Ferrari, Raffaele , Forget, Gael , Freeland, Howard , Fujiki, Tetsuichi , Gehlen, Marion , Geenan, Blair , Hallberg, Robert , Hibiya, Toshiyuki , Hosoda, Shigeki , Jayne, Steven R. , Jochum, Markus , Johnson, Gregory C. , Kang, KiRyong , Kolodziejczyk, Nicolas , Körtzinger, Arne , Le Traon, Pierre-Yves , Lenn, Yueng-Djern , Maze, Guillaume , Mork, Kjell Arne , Morris, Tamaryn , Nagai, Takeyoshi , Nash, Jonathan D. , Naveira Garabato, Alberto C. , Olsen, Are , Pattabhi Rama Rao, Eluri , Prakash, Satya , Riser, Stephen C. , Schmechtig, Catherine , Schmid, Claudia , Shroyer, Emily L. , Sterl, Andreas , Sutton, Philip J. H. , Talley, Lynne D. , Tanhua, Toste , Thierry, Virginie , Thomalla, Sandy J. , Toole, John M. , Troisi, Ariel , Trull, Thomas W. , Turton, Jon , Velez-Belchi, Pedro , Walczowski, Waldemar , Wang, Haili , Wanninkhof, Rik , Waterhouse, Amy F. , Waterman, Stephanie N. , Watson, Andrew J. , Wilson, Cara , Wong, Annie P. S. , Xu, Jianping , Yasuda, Ichiro

The Argo Program has been implemented and sustained for almost two decades, as a global array of about 4000 profiling floats. Argo provides continuous observations of ocean temperature and salinity versus pressure, from the sea surface to 2000 dbar. The successful installation of the Argo array and its innovative data management system arose opportunistically from the combination of great scientific need and technological innovation. Through the data system, Argo provides fundamental physical observations with broad societally-valuable applications, built on the cost-efficient and robust technologies of autonomous profiling floats. Following recent advances in platform and sensor technologies, even greater opportunity exists now than 20 years ago to (i) improve Argo’s global coverage and value beyond the original design, (ii) extend Argo to span the full ocean depth, (iii) add biogeochemical sensors for improved understanding of oceanic cycles of carbon, nutrients, and ecosystems, and (iv) consider experimental sensors that might be included in the future, for example to document the spatial and temporal patterns of ocean mixing. For Core Argo and each of these enhancements, the past, present, and future progression along a path from experimental deployments to regional pilot arrays to global implementation is described. The objective is to create a fully global, top-to-bottom, dynamically complete, and multidisciplinary Argo Program that will integrate seamlessly with satellite and with other in situ elements of the Global Ocean Observing System (Legler et al., 2015). The integrated system will deliver operational reanalysis and forecasting capability, and assessment of the state and variability of the climate system with respect to physical, biogeochemical, and ecosystems parameters. It will enable basic research of unprecedented breadth and magnitude, and a wealth of ocean-education and outreach opportunities.

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Article

The Global Ocean Biogeochemistry (GO-BGC) array of profiling floats to observe changing ocean chemistry and biology

2022-06 , Matsumoto, George I. , Johnson, Kenneth S. , Riser, Stephen C. , Talley, Lynne D. , Wijffels, Susan E. , Hotinski, Roberta

The Global Ocean Biogeochemistry (GO-BGC) Array is a project funded by the US National Science Foundation to build a global network of chemical and biological sensors on Argo profiling floats. The network will monitor biogeochemical cycles and ocean health. The floats will collect from a depth of 2,000 meters to the surface, augmenting the existing Argo array that monitors ocean temperature and salinity. Data will be made freely available within a day of being collected via the Argo data system. These data will allow scientists to pursue fundamental questions concerning ocean ecosystems, monitor ocean health and productivity, and observe the elemental cycles of carbon, oxygen, and nitrogen through all seasons of the year. Such essential data are needed to improve computer models of ocean fisheries and climate, to monitor and forecast the effects of ocean warming and ocean acidification on sea life, and to address key questions identified in “Sea Change: 2015–2025 Decadal Survey of Ocean Sciences” such as: What is the ocean’s role in regulating the carbon cycle? What are the natural and anthropogenic drivers of open ocean deoxygenation? What are the consequences of ocean acidification? How do physical changes in mixing and circulation affect nutrient availability and ocean productivity?

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Working Paper

Building a Community of Biogeochemistry Float Data Users: an OCB and US CLIVAR Report

2023-04-04 , Riser, Stephen C. , Fassbender, Andrea J. , Johnson, Kenneth S. , Sarmiento, Jorge L. , Talley, Lynne D. , Wijffels, Susan E. , Hotinski, Roberta , Gray, Alison R. , Takeshita, Yuichiro , Nicholson, David P. , Purkey, Sarah G. , Martz, Todd R. , Matsumoto, George I. , Cullen, Heidi

The Global Ocean Biogeochemistry (GO-BGC) array is a 5-year effort funded by the US National Science Foundation to produce and deploy 500 profiling floats equipped with biogeochemical sensors in the world ocean. Deployments began in the first quarter of 2021. To inform and engage a broad oceanographic user community, the Ocean Carbon & Biogeochemistry (OCB) and the US Climate Variability and Predictability (CLIVAR) Programs worked with GO-BGC leadership to host a virtual GO-BGC Scientific Workshop from June 28-30, 2021. The objectives of the workshop were to: • Introduce the GO-BGC plan to the global scientific community • Discuss and innovate on scientific applications of GO-BGC data • Provide background information on the flow of data and archiving • Deliver hands-on tutorials and computer code for accessing GO-BGC data Presentations and discussions were scheduled for 3-4 hours on each day using the Zoom platform. Some pre-recorded presentations were available online prior to each day’s events, so that participants could consider discussion items before the meeting. A Slack channel was also created prior to the meeting so that participants could communicate with organizers, presenters, and other attendees during the event.

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