The main part of the code development for spectral coupling has been finished. From technical point of view, at the present, the new spectral coupling scheme is working without major problems. The tests were done assuming mono-processor and multi-processor code version for optimal computation time, running the operational model on the Slovenian domain. A first comparison between the model results using the spectral and gridpoint couplings has been carried out. The mean-sea-level pressure field after three hours of integration keeps almost the same structure. It can be observed that the field with spectral coupling seems to have smaller values and to be less smooth (see Fig1 and Fig2).
The tuning of the spectral "alpha" function is absolutely important for the next step. The simplified spectral 1d shallow-water model will be used for validation and tuning. In the same time, the "alpha" function retuning for gridpoint coupling has to be considered further in order to avoid the very strong external forcing.
Figure 1 (left) : Mean-sea-level pressure field obtained by running the model with spectral coupling
Figure 2 (right) : Mean-sea-level pressure field obtained by running the model with classic coupling (Davies' relaxation scheme)