Ocean modeling has seen rapid advances over the last two decades, driven initially by investments in the science to underpin assessment and prediction of climate variability and change, coordinated by international programs such as the World Ocean Circulation Experiment (WOCE), Joint Global Ocean Flux Study (JGOFS) and Climate Variability and Predictability (CLIVAR). Climate prediction through coupled climate and earth system models continues to be a major driver and user of models of ocean circulation and carbon cycling. With growing concern about the potential impacts of ocean acidification, ocean biogeochemical models are also being used to project the likely evolution of ocean pH, alkalinity and carbonate saturation
under different CO2 emission scenarios.
With the establishment of GODAE137 in 1997 (Box 3), ocean circulation modeling entered a new
era, developing and implementing operational, eddy-resolving, data-assimilating circulation models at global, ocean basin and regional scales. This highly successful program has seen the establishment and demonstration of operational ocean circulation models by a number of groups around the world, and (critically) the establishment of the key observing infrastructure needed to support them.
These models play a similar role to operational numerical weather prediction models, and a key challenge now for this community is to transition the global operational ocean forecasting capability from its current demonstration status to the permanent, sustained and continuously improved status established for numerical weather prediction. While the immediate products are nowcasts and short-term forecasts of 3-dimensional ocean state, these programs have also provided extremely valuable information for climate and marine ecosystem research through multi-decadal hindcasts of ocean state and improvements to circulation models that can be transferred to climate models.
The success of GODAE has led to the establishment of GODAE OceanView which has a
broader mandate and scope as encapsulated in four goals:138
• The consolidation and improvement of global and regional analysis and forecasting
systems (physics).
• The progressive development and scientific testing of the next generation of ocean
analysis and forecasting systems, covering bio-geochemical and eco-systems as well as physical oceanography, and extending from the open ocean into the shelf sea and coastal waters.
• The exploitation of this capability in other applications (weather forecasting, seasonal and
decadal prediction, climate change detection and its coastal impacts, etc).
• The assessment of the contribution of the various components of the observing system
and scientific guidance for improved design and implementation of the ocean observing system.
For the most part, the work plan represents an evolution of GODAE models and capabilities, including improvements in the spatial resolution of circulation models from 10 km to 3 km (at global and regional scales), and development of prototype data-assimilating (pelagic) biogeochemical models at global and regional scales. Quasi-operational higher-resolution data- assimilation regional and shelf circulation models exist now, and one might expect to see demonstration operational systems within 3 years. Data-assimilation into biogeochemical models is an active research area, but the establishment of operational data-assimilating biogeochemical models is likely to take longer.
The further downscaling of circulation models to bay and estuary scales and the extension of biogeochemical models to end-to-end ecosystem models do not figure largely in these national and regional plans, with the exception of the US National Ocean Service (NOS). NOS applies hydrodynamic models for the development, transition and implementation of Operational Forecast Systems (OFS) in U.S. estuaries, ports, lakes and the coastal ocean. The inshore extension of ocean models must address the rapid decrease in the spatial scales of variation approaching the coast. This poses challenges for models (increased spatial resolution, requiring nested, flexible or adaptive grids, and imposing significant computational loads), but also poses major challenges for inshore observing system design and implementation (section 5.4).
To help achieve the goals of GODAE OceanView, research will be encouraged to improve operational oceanography systems in areas such as “high-resolution physical modeling, downscaling (to coastal regions), biogeochemical and ecosystem modeling, ocean-wave- atmosphere coupling, data assimilation and coupled data assimilation, error estimates, long-term reanalyses, use of new observations.” GODAE OceanView has also established five task teams. The teams for Intercomparison and Validation and Observing System Evaluation are addressing generic issues that are critically important for any operational coastal or ecosystem modeling system, including the definition of metrics to assess the quality of analyses and forecasts (e.g. forecast skills), and the use of Observing System Experiments (OSEs) and OSSEs to provide objective evaluation of alternative observing system designs. The Coastal Ocean and Shelf Seas
Task Team is focusing on the problems of downscaling global and basin models to address cross-
shelf interactions, primarily for physics and the interaction between physics and biogeochemistry, including the fate of terrestrial inputs. Because international coordination and collaboration are less well developed for coastal modeling (see below), the task team plans to focus on convening discussion forums and developing international coordination. The Task Team for Coupled Atmosphere-Ocean Prediction is focused on short to medium range time scales. The Marine Ecosystem Monitoring and Prediction Task Team is working closely with the Integrated Marine Biogeochemistry and Ecosystem Research (IMBER) program to develop and integrate models and assimilation methods for ocean biogeochemistry and marine ecosystem monitoring into operational ocean models. Initiatives such as the Advances in Marine Ecosystem
Modeling Research (AMEMR) Symposia are helping to bring the ecosystem modeling
community together, and to document progress.139