eulerian dynamical core spectra cutoff

[kangwanying1992@gmail_com]

Dear experts and colleagues,I am wondering if anyone has tried to truncate the wavenumber in west-east direction in a spectral dynamic core (eulerian core), and will appreciate any suggestions on how to do it.Up to now, I am thinking of two ways to do it:create or obtain SCRIP format grid files for the atmosphere, land and ocean grids. The document mentioned the supporting script will be developed in CESM1.2.x, but I am not sure where to get it and how to use it.2) truncate it when integrating.  I checked how eulerian dynamical core evaluates the tendency and update the model state. It seems that the only thing done in spectra space is the linear dynamical terms (done in dyndrv.F90) and other things including physics processes and advection are all done in grid space. After the linear dynamical terms be evaluated in spectral space, the tendency is transformed to grid space. Together with the tendency contributed by physics and advection, everything is updated in grid space. If I understand it correctly, the model spent most of its time in grid space and there is nowhere I can cut-off the spectra of model state variables. 
Thanks in advance!Best,Wanying