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I have a question about namcouple. There is a line, which looks like P 2 P 2 OASIS tutorial says that it is first dimension characteristic (‘P’: periodical; ‘R’: regional) and first dimension number of overlapping grid points. What does this mean? Is this line necessary to interpolate fields between WRF and NEMO model grids? Can I ignore the line if I have identical grids for both models?
A grid can have overlapping grid points in the x dimension and this information is needed in order to perform a proper interpolation. For example the NEMO global grid has 2 overlapping grid points in its first dimension, and so "P 2" should be given for the NEMO grid. If WRF has a regional grid, then"R 0" should be provided; if WRF has a global grid with no overlapping grid points, you should indicate "P 0". For example, if the coupling exchange implies a regridding from a WRF global grid with no overlapping grid points to the NEMO grid, then "P 0 P 2" should be provided on that line. This information is mandatory so you have to put something on that line. Let me know if this helps ...
Thank you for the answer. I would like to clarify a couple of things. 1. As far as I understand, "P" means global grid. For example, I have a global grid with 361 points in x direction with longitudes 0, 1, ...,359, 360 For this grid "P 1" should be provided. 2. If I have a regional grid, the number is always "0" (i.e. "R 0"), because regional grid can not have overlapping points. Am I correct?
Yes, you are right. In your case, the point at longitude 0 overlaps the point at longitude 360, so indeed you have to put "P 1". And yes for a regional grid, you always have to put "R 0".
