Two way interactive air-sea coupling - setup and case study

Using the Earth System Modeling Framework (ESMF), the Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPS® ) and the NRL Coastal Ocean Model (NCOM) are coupled in a two-way interactive fashion, where both models are exchanging variable fields during the numerical simulation. The emphasis of this presentation is on the technical setup of the coupled system. In addition to the original model grids, two exchange grids were created to facilitate the exchange of variables between the atmosphere and the ocean. The novel approach eliminates the need for collocated grid points and allows arbitrary projections and grid sizes of the models.

Preliminary results using COAMPS with four and NCOM with two nested grids in an experiment over the area off the coast of Southern California are presented for two cases. The results of the two-way coupled run are compared with one-way interactive scheme, and evaluated with available in-situ and remote measurements. Computational overhead is also discussed in comparison to the non-ESMF one-way coupling.