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Adjoint model of the GYRE configuration of NEMO by using the YAO software

M. Berrada , C. Talandier, M. Crépon, F. Badran, S. Thiria Work supported by the SHOM (Hydrographic and Oceanographic Department of the French Navy) under SINOBAD project LOCEAN-UPMC NEMO user meeting Paris, 2-3, July 2009.

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Adjoint model of the GYRE configuration of NEMO by using the YAO software

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  1. M. Berrada , C. Talandier, M. Crépon, F. Badran, S. Thiria Work supported by the SHOM (Hydrographic and Oceanographic Department of the French Navy) under SINOBAD project LOCEAN-UPMC NEMO user meeting Paris, 2-3, July 2009 Adjoint model of the GYRE configuration of NEMO by using the YAO software

  2. Goal : feasibility of the implementation of the adjoint model of NEMO under YAO Work in progress

  3. GYRE configuration • Idealized configuration of the physical part of NEMO • The domain is a limited area in the North of the Atlantic ocean (Gulf stream region) • The horizontal dimension 32x22 and 31 vertical levels GYRE area localisation

  4. The forecasting of the ocean state depends on the initial environment Accurate initial ocean environment V=(u,v,w) velocity ssh the sea surface height T Temperature S salinity Data assimilation by the variational approach Control parameters Initial ocean environment

  5. Variational assimilation Conceptual of an adjoint-based iterative scheme

  6. YAO • Semi- automatic generator of the adjoint code • Based on a modular graph structure • The modular graph is a data flow diagram which describes the underlying physical model • It consists of a set of modules, where the input of each one is provided by the output of its predecessors

  7. M’2 YAO: Modular Graph Modular graph in a point of the grid M2 d x21 d y21 d x22 M3 M1 d x31 d y31 d y11 d x32 d x11 d y32 d x33 d y12 Backward model Forward model Define the modular graph structure of the model Coding of the local functions fq Coding of the Jacobean

  8. M1 M1 M1 M1 M1 M2 M2 M2 M2 M2 M3 M3 M3 M3 M3 M1 M1 M1 M1 M1 M1 M2 M2 M2 M2 M2 M2 x x M3 M3 M3 M3 M3 M3 M1 M1 M1 M1 M1 M1 M2 M2 M2 M2 M2 M2 x x M3 M3 M3 M3 M3 M3 t1 t0 t2 t3 Time evolution of the modular graph of the space Modular raph of the space Modular graph in a point of the grid

  9. Accomplished work • Defined the modular graph structure of the GYRE model under YAO • Coded the forward model M1 y11 d x11 d y12 d • It remains the implementation of the Jacobean of each module which is needed for the backpropagation (This will be done at the end of September) • I shall be ready to cooperate with people wishing to solve assimilation problems

  10. Accomplished work • Comparison: GYRE-YAO vs GYRE-Fortran (accuracy ) Comparison of the intensity of the horizontal velocity in the sea surface at t=100 Comparison of the ssh at t=100

  11. Accomplished work Comparison of the temperature in the sea surface at t=100 Comparison of the salinity in the sea surface at t=100

  12. Flexibility: Modifying the model and its adjoint is straightforward due to modular graph structure One can consider a more complex function as a module for the YAO graph and uses Tapenade (or other) to get the local adjoint Very useful for sensitivity experiments Conclusion

  13. Thank you!

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