I am currently trying to set up a grid for a nested model using the NEMOGCM/TOOLS/NESTING routines. The grid of the parent model has curvilinear coordinates and the i,j axis are rotated by an angle from geographical north.
Running create_coordinates.exe with following definitions in the namelist.input
&coarse_grid_files parent_coordinate_file = '/path/to/parent/model/coordinates.nc' parent_meshmask_file = '/path/to/parent/model/mesh_mask.nc' / &nesting imin = 259 imax = 310 jmin = 183 jmax = 202 rho = 4 rhot = 2 / &nemo_coarse_grid jpizoom = 1 jpjzoom = 1 /
creates a new coordinates.nc file with the desired smaller grid spacing, however, I have noticed some issues - in particular with regards to the grid staggering. The problem is illustrated in attached figure.
- The first thing I was wondering about is why the T-points of the parent grid (red dots) do not coincide with every fourth T-point of the nested grid (blue x)?
- The more striking feature is that the staggering of the nested grid does not take into account the grid rotation which means that T-points (blue) and U-points (yellow) share the same latitude and T-points (blue) and V-points (green) share the same longitudes.
My question is if I have overlooked something of if rotated grid are currently not supported in the nesting tools?
Any input on that is much appreciated.
It has been confirmed that the incorrect U- and V- coordinates are a bug - see Ticket #2082. Thanks to Michael Dunphy for the fix.chrenkl2018-05-09 14:21 CEST (2 weeks ago)