Stammer Detlef

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Stammer
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Detlef
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  • Article
    Putting it all together: Adding value to the global ocean and climate observing systems with complete self-consistent ocean state and parameter estimates.
    (Frontiers Media, 2019-03-04) Heimbach, Patrick ; Fukumori, Ichiro ; Hill, Christopher N. ; Ponte, Rui M. ; Stammer, Detlef ; Wunsch, Carl ; Campin, Jean-Michel ; Cornuelle, Bruce D. ; Fenty, Ian ; Forget, Gael ; Kohl, Armin ; Mazloff, Matthew R. ; Menemenlis, Dimitris ; Nguyen, An T. ; Piecuch, Christopher G. ; Trossman, David S. ; Verdy, Ariane ; Wang, Ou ; Zhang, Hong
    In 1999, the consortium on Estimating the Circulation and Climate of the Ocean (ECCO) set out to synthesize the hydrographic data collected by the World Ocean Circulation Experiment (WOCE) and the satellite sea surface height measurements into a complete and coherent description of the ocean, afforded by an ocean general circulation model. Twenty years later, the versatility of ECCO's estimation framework enables the production of global and regional ocean and sea-ice state estimates, that incorporate not only the initial suite of data and its successors, but nearly all data streams available today. New observations include measurements from Argo floats, marine mammal-based hydrography, satellite retrievals of ocean bottom pressure and sea surface salinity, as well as ice-tethered profiled data in polar regions. The framework also produces improved estimates of uncertain inputs, including initial conditions, surface atmospheric state variables, and mixing parameters. The freely available state estimates and related efforts are property-conserving, allowing closed budget calculations that are a requisite to detect, quantify, and understand the evolution of climate-relevant signals, as mandated by the Coupled Model Intercomparison Project Phase 6 (CMIP6) protocol. The solutions can be reproduced by users through provision of the underlying modeling and assimilation machinery. Regional efforts have spun off that offer increased spatial resolution to better resolve relevant processes. Emerging foci of ECCO are on a global sea level changes, in particular contributions from polar ice sheets, and the increased use of biogeochemical and ecosystem data to constrain global cycles of carbon, nitrogen and oxygen. Challenges in the coming decade include provision of uncertainties, informing observing system design, globally increased resolution, and moving toward a coupled Earth system estimation with consistent momentum, heat and freshwater fluxes between the ocean, atmosphere, cryosphere and land.
  • Article
    Models : tools for synthesis in international oceanographic research programs
    (Oceanography Society, 2010-09) McGillicuddy, Dennis J. ; deYoung, Brad ; Doney, Scott C. ; Glibert, Patricia M. ; Stammer, Detlef ; Werner, Francisco E.
    Through its promotion of coordinated international research programs, the Intergovernmental Oceanographic Commission (IOC) has facilitated major progress on some of the most challenging problems in oceanography. Issues of global significance—such as general ocean circulation, the carbon cycle, the structure and dynamics of ecosystems, and harmful algal blooms—are so large in scope that they require international collaboration to be addressed systematically. International collaborations are even more important when these issues are affected by anthropogenic processes— such as climate change, CO2 enhancement, ocean acidification, pollution, and eutrophication—whose impacts may differ greatly throughout the global ocean. These problems require an entire portfolio of research activities, including global surveys, regional process studies, time-series observations, laboratorybased investigations, and satellite remote sensing. Synthesis of this vast array of results presents its own set of challenges (Hofmann et al., 2010), and models offer an explicit framework for integration of the knowledge gained as well as detailed investigation of the underlying dynamics. Models help us to understand what happened in the past, and to make predictions of future changes—both of which support the development of sound policy and decision making. We review examples of how models have been used for this suite of purposes, focusing on areas where IOC played a key role in organizing and coordinating the research activities.
  • Article
    Measuring global ocean heat content to estimate the Earth energy Imbalance
    (Frontiers Media, 2019-08-20) Meyssignac, Benoit ; Boyer, Tim ; Zhao, Zhongxiang ; Hakuba, Maria Z. ; Landerer, Felix ; Stammer, Detlef ; Kohl, Armin ; Kato, Seiji ; L’Ecuyer, Tristan S. ; Ablain, Michaël ; Abraham, John Patrick ; Blazquez, Alejandro ; Cazenave, Anny ; Church, John A. ; Cowley, Rebecca ; Cheng, Lijing ; Domingues, Catia M. ; Giglio, Donata ; Gouretski, Viktor ; Ishii, Masayoshi ; Johnson, Gregory C. ; Killick, Rachel E. ; Legler, David ; Llovel, William ; Lyman, John ; Palmer, Matthew D. ; Piotrowicz, Stephen R. ; Purkey, Sarah G. ; Roemmich, Dean ; Roca, Rémy ; Savita, Abhishek ; von Schuckmann, Karina ; Speich, Sabrina ; Stephens, Graeme ; Wang, Gongjie ; Wijffels, Susan E. ; Zilberman, Nathalie
    The energy radiated by the Earth toward space does not compensate the incoming radiation from the Sun leading to a small positive energy imbalance at the top of the atmosphere (0.4–1 Wm–2). This imbalance is coined Earth’s Energy Imbalance (EEI). It is mostly caused by anthropogenic greenhouse gas emissions and is driving the current warming of the planet. Precise monitoring of EEI is critical to assess the current status of climate change and the future evolution of climate. But the monitoring of EEI is challenging as EEI is two orders of magnitude smaller than the radiation fluxes in and out of the Earth system. Over 93% of the excess energy that is gained by the Earth in response to the positive EEI accumulates into the ocean in the form of heat. This accumulation of heat can be tracked with the ocean observing system such that today, the monitoring of Ocean Heat Content (OHC) and its long-term change provide the most efficient approach to estimate EEI. In this community paper we review the current four state-of-the-art methods to estimate global OHC changes and evaluate their relevance to derive EEI estimates on different time scales. These four methods make use of: (1) direct observations of in situ temperature; (2) satellite-based measurements of the ocean surface net heat fluxes; (3) satellite-based estimates of the thermal expansion of the ocean and (4) ocean reanalyses that assimilate observations from both satellite and in situ instruments. For each method we review the potential and the uncertainty of the method to estimate global OHC changes. We also analyze gaps in the current capability of each method and identify ways of progress for the future to fulfill the requirements of EEI monitoring. Achieving the observation of EEI with sufficient accuracy will depend on merging the remote sensing techniques with in situ measurements of key variables as an integral part of the Ocean Observing System.
  • Article
    Ocean climate observing requirements in support of climate research and climate information
    (Frontiers Media, 2019-07-31) Stammer, Detlef ; Bracco, Annalisa ; AchutaRao, Krishna ; Beal, Lisa M. ; Bindoff, Nathaniel L. ; Braconnot, Pascale ; Cai, Wenju ; Chen, Dake ; Collins, Matthew ; Danabasoglu, Gokhan ; Dewitte, Boris ; Farneti, Riccardo ; Fox-Kemper, Baylor ; Fyfe, John ; Griffies, Stephen M. ; Jayne, Steven R. ; Lazar, Alban ; Lengaigne, Matthieu ; Lin, Xiaopei ; Marsland, Simon ; Minobe, Shoshiro ; Monteiro, Pedro M. S. ; Robinson, Walter ; Roxy, Mathew Koll ; Rykaczewski, Ryan R. ; Speich, Sabrina ; Smith, Inga J. ; Solomon, Amy ; Storto, Andrea ; Takahashi, Ken ; Toniazzo, Thomas ; Vialard, Jérôme
    Natural variability and change of the Earth’s climate have significant global societal impacts. With its large heat and carbon capacity and relatively slow dynamics, the ocean plays an integral role in climate, and provides an important source of predictability at seasonal and longer timescales. In addition, the ocean provides the slowly evolving lower boundary to the atmosphere, driving, and modifying atmospheric weather. Understanding and monitoring ocean climate variability and change, to constrain and initialize models as well as identify model biases for improved climate hindcasting and prediction, requires a scale-sensitive, and long-term observing system. A climate observing system has requirements that significantly differ from, and sometimes are orthogonal to, those of other applications. In general terms, they can be summarized by the simultaneous need for both large spatial and long temporal coverage, and by the accuracy and stability required for detecting the local climate signals. This paper reviews the requirements of a climate observing system in terms of space and time scales, and revisits the question of which parameters such a system should encompass to meet future strategic goals of the World Climate Research Program (WCRP), with emphasis on ocean and sea-ice covered areas. It considers global as well as regional aspects that should be accounted for in designing observing systems in individual basins. Furthermore, the paper discusses which data-driven products are required to meet WCRP research and modeling needs, and ways to obtain them through data synthesis and assimilation approaches. Finally, it addresses the need for scientific capacity building and international collaboration in support of the collection of high-quality measurements over the large spatial scales and long time-scales required for climate research, bridging the scientific rational to the required resources for implementation.
  • Article
    Towards comprehensive observing and modeling systems for monitoring and predicting regional to coastal sea level
    (Frontiers Media, 2019-07-25) Ponte, Rui M. ; Carson, Mark ; Cirano, Mauro ; Domingues, Catia M. ; Jevrejeva, Svetlana ; Marcos, Marta ; Mitchum, Gary ; van de Wal, Roderik S.W. ; Woodworth, Philip L. ; Ablain, Michaël ; Ardhuin, Fabrice ; Ballu, Valerie ; Becker, Mélanie ; Benveniste, Jérôme ; Birol, Florence ; Bradshaw, Elizabeth ; Cazenave, Anny ; De Mey-Frémaux, Pierre ; Durand, Fabien ; Ezer, Tal ; Fu, Lee-Lueng ; Fukumori, Ichiro ; Gordon, Kathy ; Gravelle, Médéric ; Griffies, Stephen M. ; Han, Weiqing ; Hibbert, Angela ; Hughes, Chris W. ; Idier, Deborah ; Kourafalou, Vassiliki H. ; Little, Christopher M. ; Matthews, Andrew ; Melet, Angelique ; Merrifield, Mark ; Meyssignac, Benoit ; Minobe, Shoshiro ; Penduff, Thierry ; Picot, Nicolas ; Piecuch, Christopher G. ; Ray, Richard D. ; Rickards, Lesley ; Santamaría-Gómez, Alvaro ; Stammer, Detlef ; Staneva, Joanna ; Testut, Laurent ; Thompson, Keith ; Thompson, Philip ; Vignudelli, Stefano ; Williams, Joanne ; Williams, Simon D. P. ; Wöppelmann, Guy ; Zanna, Laure ; Zhang, Xuebin
    A major challenge for managing impacts and implementing effective mitigation measures and adaptation strategies for coastal zones affected by future sea level (SL) rise is our limited capacity to predict SL change at the coast on relevant spatial and temporal scales. Predicting coastal SL requires the ability to monitor and simulate a multitude of physical processes affecting SL, from local effects of wind waves and river runoff to remote influences of the large-scale ocean circulation on the coast. Here we assess our current understanding of the causes of coastal SL variability on monthly to multi-decadal timescales, including geodetic, oceanographic and atmospheric aspects of the problem, and review available observing systems informing on coastal SL. We also review the ability of existing models and data assimilation systems to estimate coastal SL variations and of atmosphere-ocean global coupled models and related regional downscaling efforts to project future SL changes. We discuss (1) observational gaps and uncertainties, and priorities for the development of an optimal and integrated coastal SL observing system, (2) strategies for advancing model capabilities in forecasting short-term processes and projecting long-term changes affecting coastal SL, and (3) possible future developments of sea level services enabling better connection of scientists and user communities and facilitating assessment and decision making for adaptation to future coastal SL change.