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Ocean Surface Topography from Space
Toward the Next Generation of Altimeter Data Assimilation for Physical Ocean and Marine Ecosystem Monitoring and Prediction


Pierre Brasseur - (LEGI)

  Lars Nerger
Jens Schröter
Joaquim Ballabrera
Bernard Barnier
Pierre-Antoine Bouttier
Jean-Michel Brankart
Emmanuel Cosme
Thierry Penduff
Jacques Verron
Clément Fontana
  Eric Blayo
Laurent Debreu
Arthur Vidard
Nicolas Ferry
Charles-Emmanuel Testut
Laurent Bertino
Alexander Barth
Jean-Marie Beckers
Peter-Jan Van Leeuwen
(LJK, Grenoble)
(LJK, Grenoble)
(LJK, Grenoble)
(NERSC, Bergen)
(ULG, Liège)
(ULG, Liège)


Toward the Next Generation of Altimeter Data Assimilation for Physical Ocean and Marine Ecosystem Monitoring and Prediction
Illustration of the testbed altimeter data assimilation configurations (instantaneous SSH is shown on both panels) that will be considered to assimilate altimetry with other data sources: the SeaBASS configuration (upper left) will enable testing of assimilation methods and assessing performance of multi-satellite altimetry; the NATL4/LOBSTER (upper right) will be used as a pre-operational testbed for multi-source assimilation experiments; the Global Mercator-Ocean configuration (lower panel, showing also sea-ice extent in white) will be hosting the most mature assimilation developments and reanalyses production. This cascade of configurations of increasing complexity will enable back-and-forth academic-to-operations revisits of assimilation approaches best suited to altimeter data assimilation.
Scope of the proposal. The overarching objective of this proposal will to further develop, implement and assess advanced methods for the assimilation of altimeter data, in combination with other data sources, into the next generation of ocean circulation and ecosystem models. The project will uniquely contribute to the development of operational oceanography in the context of on-going programmes such as GMES, and will enable better understanding of the role of the ocean on climate variability through the production of improved ocean reanalyses based on altimetry and other observational components, in the framework of CLIVAR/GSOP.

Approach and work statement. The methods that will be explored and further developed to assimilate altimeter data will be multiple, taking advantage of the most recent advances in the field of stochastic modelling, statistical estimation and optimal control. On the one hand, well established methodologies such as Kalman-type filters and smoothers and variational methods will be expanded and complexified to take into account non-Gaussian error statistics or non-linear model dynamics. On the other hand, more generic methods such as particle filters will be adapted to cope with the huge dimension of realistic ocean models.

Altimetry from the JASON suite, and from forthcoming missions (HY-2A, Sentinel-3, SARAL/Altika), will be the primary source of data for this project, in conjunction with ENVISAT, Cryosat-2 and other historical altimetry data sets, GRACE and GOCE for gravimetry, and SMOS for salinity. A particular focus will be set on the use of multiple data sources including in situ observations and to their optimal complementarity to altimetry.

Expected impact. The application of the assimilation methods will enable improved ocean real-time analyses as well as multi-year reanalyses, providing a unique source of ocean information to

  • improve our understanding of the role of the mesoscale variability on the general circulation,
  • develop our capability to monitor and forecast the mesoscale/submesoscale variability,
  • contribute to the scientific understanding, monitoring and forecasting of seasonal to interannual climate anomalies and climate variability,
  • demonstrate the capability of coupled physico-biological systems with data assimilation to provide a rationale basis for the future management of living resources, especially in coastal regions and for the understanding of the ocean carbon dioxide storage and fluxes.

Proposing team. The group of PIs involved in this proposal has played a significant role in France and Europe with regard to the development of data assimilation in oceanography through their fundamental research work, and their contribution to the emergence of increasingly efficient operational systems. The expertise of the proposing team is broad enough to cover the variety of most advanced assimilation approaches, in such a way as to stimulate open dialog and cross-fertilization of ideas between the proposal participants.

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