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"Wrong" or not the ideal map projection


New member
Dear forum.

I accidentally ran a long-period simulation using the 'Mercator' projection for a 3-nested domain (9km, 3km, 1km) case over the North Sea.
I know that the suggested projection for this area is 'Lambert'.
So I conducted a weekly validation run and there are discrepancies between the two different projection runs (i.e. 'Mercator' vs 'Lambert'), as expected.
I am not sure if this would make sense, however, I was wondering if there is any possibility to post-process the Mercator-executed WRF runs and project them to a Lambert map to avoid proceeding with the long-period run from scratch?
How could I confirm that the 'Mercator' runs are wrong?
Thank you very much in advance.
Did you see large differences between results on Mercator and Mercator projections? I don't think map projection can affect the accuracy of model simulation. It only affects the distortion degree of model grids ( represented by map factor in WRF) and thus the time step may need to be adjusted.

For your case, if the model runs to the end successfully, I wouldn't worry for the results even if the map projection is not appropriate.

Remapping the results to lambert projection won't improve the accuracy.
Thank you very much for your reply.

The model ran successfully. However, yes, I can detect discrepancies (e.g. in wind speed profiles at specific time steps), especially in the lower boundary layer (e.g. <1000m height).

I understand that remapping won't improve the accuracy.

However, I wonder, if I continue the year-long simulation switching to Lambert could the two different projection results be combined?
Furthermore, I don't know if this is helpful. However, the MAPFAC_M for the Mercator case has a min_value = 0.9048, and a max_value = 0.9633.
While, for the Lambert case I get: min_value = 0.9990, and a max_value = 0.9995, which makes more sense.

Thank you again for your help.