2. The vision
3. Rationale and Objectives
4. The benefits
6. The schedule
In early 1997, the Global Ocean Data Assimilation Experiment (GODAE) concept emerged from discussions of the Ocean Observation Panel for Climate (OOPC) with the Committee on Earth Observing Satellites (CEOS) and its Integrated Global Observing Strategy.
The concept was developed in the belief that attracting the resources necessary for an adequate long-term global ocean observing system for monitoring the ocean depends upon a clear demonstration of the feasibility and value of such a system (Smith and Lefebvre, 1997). Using the First GARP Global Experiment (FGGE) as a model, OOPC proposed GODAE as an experiment in which a comprehensive, integrated observing system would be established and held in place for several years and the data assimilated into state-of-the art models of the global ocean circulation in near real-time.
Progress across a wide range of ocean research and applications depends upon the prompt and dependable availability of ocean information products. Recent scientific and technical progress suggests that significant improvement in the quality of these marine services is feasible. However, a coordinated international effort is required to achieve this improvement. The Global Ocean Data Assimilation Experiment (GODAE) seeks to provide a framework for this effort. The vision is
"A global system of observations, communications, modeling and assimilation, that will deliver regular, comprehensive information on the state of the oceans, in a way that will promote and engender wide utility and availability of this resource for maximum benefit to the community."
GODAE aims to make this concept a reality, making ocean monitoring and prediction a routine activity in a manner similar to weather forecasting. GODAE will contribute to an information system for the global ocean that will serve interests from climate and climate change through to ship routing and fisheries.
GODAE will create the conditions for an efficient and effective global ocean measurement network, provided through a variety of direct and remote methods, and sustained for the long-term on the basis of demonstrated, practical utility. The raw and processed information (data and analyses) are distributed globally via a system of communications and data serving that satisfy the demand for immediacy and timeliness of information, in a way that makes clear the character and quality of data sets.
The rationale behind GODAE recognizes both societal need and scientific and technical opportunity. There is an accepted demand for an efficient, integrated system for global ocean products, provided regularly, and in real-time. Recent scientific and technical progress suggests the solutions to this demand are now both feasible and affordable. The underlying rationale for GODAE as an international experiment is that the vision will not be realized serendipitously. The needed capacity will not be realized without a concerted effort to ensure, first, proper integration of the components and, second, the commitment to proving value and viability.
The specific objectives are to:
|I||Apply state-of-the art ocean models and assimilation methods to produce short-range open-ocean forecasts, boundary conditions to extend predictability of coastal and regional subsystems, and initial conditions for climate forecast models.|
|II||Provide global ocean analyses for developing improved understanding of the oceans, improved assessments of the predictability of ocean variability, and as a basis for improving the design and effectiveness of a global ocean observing system.|
The specific goals are to:
- Coordinate and foster a more efficient, responsive and sustainable system for data assembly, quality control and access.
- Improve public access to and awareness of the many marine services products, both operational and research that are available.
- Foster the development of a shared "Common" of ocean information and tools for the production of improved ocean products.
- Foster the production and analysis of improved ocean service products.
- Undertake experiments to assess the utility of various ocean data streams for different applications.
- Guide the evolution of a global ocean observing system, until the system and tools are able to produce ocean service products that meet the needs of the GODAE sponsors.
GODAE will address such questions as
- What accuracy, skill and value to users is achievable with present state-of-the-art observation, modeling and assimilation techniques for analyses and forecasts of (a) the mixed-layer (out to 3-5 days ahead), (b) the ocean mesoscale (out to 10-20 days ahead), and (c) seasonal and longer-term variability?
- What use can be made of these open ocean analyses and forecasts to improve the accuracy and value of (a) estimates of currents and their variability along the shelf break, and (b) analyses and forecasts of waters on the continental shelf?
The objectives are intentionally broad in the belief that wide utilization and exploitation are essential ingredients for cost-efficiency and relevance to society. There is also the desirable balance between the practical and applied goals and the long-term strategic objectives. The scope is determined by the complementary and synergistic areas of real-time, high-resolution, operational oceanography and near real-time climate applications. The essential fields are ocean temperature, velocity, sea level and salinity.
Climate and seasonal forecasting, navy applications, marine safety, fisheries, the offshore industry and management of shelf/coastal areas are among the expected beneficiaries of GODAE. From the organized infrastructure, the partnerships, the collaborations and coordination amongst the participating groups and from the outreach activities for value added products, many useful outcomes can be anticipated. These include:
- An improved capacity for prediction for coastal, shelf and regional subsystems through the provision of suitable oceanic initial and boundary conditions;
- Better initial conditions for climate predictions and analyses for validation of climate simulations,
- Improved open ocean nowcasts and forecasts;
- Integrated analyses or reanalyses for research programs (e.g. CLIVAR);
- Description of the ocean circulation and physics upon which more specialized systems, such as ecosystem models, can be developed and tested;
- A foundation for hypothesis testing, process studies and further experimentation, much as is commonplace in numerical weather prediction today;
- Improved availability and utility of ocean data;
- A methodology for systematic handling, quality control and consistent scientific interpretation (analysis) of special data sets such as those from process studies and arising from incidental exploration;
- Assessments of the observing system and of the utility of new ocean data sets (e.g., new altimetric missions, sea surface salinity from satellites);
- Model testing and improvement;
- A viable, long-term observing system (GOOS); and
- Development of an enhanced user base and suite of applications.
The implementation of GODAE is being guided by a set of principles and guidelines. The concept of a GODAE Common is being used to foster free and open exchange among the GODAE Partners. The Common comprises data, products, servers, and the accumulated knowledge base. The guiding principle in determining relevance is that an activity must make a significant contribution to the development of the GODAE Common. The GODAE strategy also seeks to build upon, work with, and leverage off existing research and operational capabilities.
The essential elements of GODAE are observational networks, models and estimation tools. In the GODAE context, these elements are inextricably linked and integrated, with obvious interdependencies. The generation of globally consistent fields of the ocean state through the synthesis of multivariate satellite and in situ data streams with models is an identifying characteristic of GODAE. Remotely sensed data from the observational network provide the only real avenue to detailed global coverage. The GODAE requirements for remote data focus on satellite altimetry, sea surface temperature and surface wind vectors. There is a continued requirement for direct measurements of ocean temperature and salinity profiles. For GODAE, high priority is attached to global coverage and the complementarity between in-situ and remote sensing data. Argo, a global array of profiling floats, is a GODAE Pilot Project that constitutes a major step forward in both these respects. Recent initiatives to develop a sustained global ocean observing system offer the potential to satisfy GODAE data needs.
More effective data assembly, improvements in data availability and utility, more timely data delivery, and improvements in the quality of the data stream are among the key data processing needs. The models are required to interpret, interpolate and extrapolate, in space and time, the incomplete information provided by the in situ and remote data streams. The implementation of state estimation tools will often be model-specific, and it can be anticipated that a variety of model and assimilation approaches will be used.
GODAE outputs will include coherent, organized data sets, synoptic ocean analyses, short-range ocean forecasts, high-quality scientific reanalyses, and statistical attributes and errors for products. Analyses will be consistent with dynamical and physical constraints and knowledge of observed and model forecast error statistics, and directed toward a variety of end applications. Outreach to potential users will be established to build dynamic relationships and thereby maximize the value of the GODAE effort.
Planning the implementation of GODAE requires identification of all the necessary components, identification of the international Partners who will build, conduct and assess the experiment, identification of technology challenges such as the provision of adequate computational resources and the real-time distribution of products, identification of the mechanisms and organizations that will facilitate the development of the Common, and definition of the implementation schedule. The scope and international nature of GODAE require distributed data assembly and serving, multiplicity of assimilation products, distributed product serving and archiving, and a multiplicity of application centers. The components include
- measurement networks,
- telecommunications and data assembly networks,
- data servers,
- modeling and assimilation centers or groups,
- computational resources,
- product servers,
- application centers or service providers, and
- end users.
When GODAE was conceived, the period 2003-2005 appeared optimal for the demonstration of viability in terms of likely observational capacity and scientific and technical capability. On this time scale, it also seemed feasible to attract the needed material and intellectual investment.
GODAE is being implemented in four phases, beginning with the concept (1998-1999), followed by development (2000-2002) the operational demonstration (2003-2005), and finishing with a consolidation and transition phase (2006-2007). Considerable attention will be devoted to putting in place a set of verifiable performance metrics to monitor the ongoing performance of GODAE, to guide its evolution, and to measure the success of GODAE in fulfilling its objectives.
The process of defining and executing a range of Pilot Projects, work programs and implementation tasks, including Argo, remote-sensing assessments and data delivery has begun. An International GODAE Steering Team and a GODAE Office have been established with the support of GODAE patrons. Partnerships within the Integrated Global Observing Strategy are being used to integrate GODAE needs with other groups. The long-term legacy of GODAE will be a set of observing and data assimilation systems that will contribute to the core of the Global Ocean Observing System and to its national implementations.
(Last Updated: 16-10-2007)