Use the MERIDIONAL keyword to correct for the convergence of longitude lines at the poles. When deriving divergence and stretching deformation grids (DVG and DST), specify MERIDIONAL=YES to subtract the following correction term from the calculation.


When deriving vorticity, absolute vorticity, or shear deformation grids (VOR, ABV, or DSH), specify MERIDIONAL=YES to add the following correction term to the calculation.


For both the correction terms above: