engleski

Coupling COSMO with the WAM model

In order to account for the full interaction between the atmosphere and the wind generated ocean waves, the COSMO model has been coupled to the WAM model. The coupling has been done in terms of a new communication and interpolation library that accounts for the different ways of grid partitioning in the two models. The communication library accommodates also communication tools for a further coupling to a circulation model on structured meshes. Having at disposal N processors, the technique of parallelization implies to decompose them as Nocn + Nwav + Natm = N (ocn - ocean ; wav - waves ; atm - atmosphere). Computationally, this means to split the MPI_COMM_WORLD into subsets by using the MPI_COM_SPLIT command. Having done that, each model uses a OCN_COMM_WORLD, ATM_COMM_WORLD and WAV_COMM_WORLD. The coupling is done at well defined times and provides time values of the fields, i.e. no averaging is done. The models are fully synchronized. Within the code the interpolation coefficients are computed. We use linear interpolation and the coefficients are computed from the lon-lat characteristics of each model grid. In this way each model can run on any grid resolution/constellation. The talk is organized as follows: first we discuss the physical need for a two-way coupling of atmosphere and ocean Then we discuss the related methodology and present the new custom made coupling library. In the last part of the talk we hope to show the first results of the coupled atmosphere-wave model.

model coupling; atmosphere model; wave model

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