How to manipulate the restart file? (u,v) field in the upper troposphere

[jihwang@colorado_edu]

Dear All:I was wondering if anyone knows how to manipulate the (u,v) field in the atmosphere restart files.I made a B_2000_CAM5 run on SE ne30 grid for a few years. Then I want to play with the (u,v) field at, say 200mb, or any level that does not have orography. In the history output, I can easily find the (u,v) field (48602 grid points) at any level and the Lat/Lon of any grid point, multiply the (u,v) by 1.1 for instance, and put them back to the history output. However, when I ncdump my restart files, I was surprised to see there are a lot more grid points for (u,v) field (86400 grid points), and they don't come with Lat/Lon.If I want to modify the (u,v) field in the restart files in the way that I can see some wind burst in some region, how should I do it?Thank you. Any insight appreciated. Best Regards,Wang

 

[jedwards]

The SE grid is a cubed sphere and writes it's output on the cubed sphere grid, this is represented in netcdf as a one dimensional field at point lat(i), lon(i) for i=1,86400.You can use tools like ncl or nco to find and modify your region of interest.   

 

[jihwang@colorado_edu]

Thank you very much.When I looked at the history file, I could see the lat(i) and lon(i), for i=1,2,...,48602.When I looked at the restart file, I could not find the lat(i) and lon(i) anywhere. Does ncl or nco use some tool to find the lat/lon in the restart file?Thanks again. 

 

[olson]

   Hi, Wang,

     On restarts, the u and v are on the SE "dynamics" grid.  The
 number of points on the SE dynamics grid (86400) is roughly
 a factor of 16/9 the number of physics gridpoints(48602).  The
 extra points on the dynamics grid turn out to just be duplicates
 of some of the physics points.  As you discovered, the lats/lons
 for the dynamics grid are not dumped to the restart file.  I have
 a fortran file on /glade modified to dump those lats/lons to the
 restart file:

   /glade/scratch/olson/modified_restart

 restart_dynamics.F90 lives in the directory components/cam/src/dynamics/se

  This copy came originally from the tag cesm2_0_beta03.  I have both
 the original and the modified copy for comparison on how to modify your
 copy.  Once modified, run the model for a timestep to get a restart
 file that will also include the lats/lons for the dynamics grid (ncol_d)

    Good luck