This procedure "surgery" is determining the number of longitudes for each latitude of a gaussian reduced grid, defined by :
– the number of latitudes NDGL,
– the maximum number of longitudes NDLON,
– the truncation NSMAX.

The job is split in 2 parts :
– first part is the computation of the Legendre polynomials onto a file (done by Arpege/128 bits)
– second part is the computation of the reduced grid, after reading the Legendre polynomials file (done by a specific program, adapted from the subroutine surgri.F)

How to use it :

– 1/ Copy the following file on VPP : mrpm602/rgrid/surgery and set your favourite values for NDGL, NDLON, NSMAX (Beware : set the nominal truncation, not twice its value : the procedure is doing by itself the multiplication by 2 !) Remark : this procedure works for quadratic grids ; if you are using non-quadratic grid, you should set for NSMAX the equivalent truncation you would have for a quadratic grid.
– 2/ Submit the script
– 3/ Enjoy the result on the *.o* file
– 4/ ALWAYS congratulate or damn the builder at email adress ryad.elkhatib@meteo.fr

More about it ?

Then explore the directory mrpm602/rgrid on VPP, everything is public !