(Notes by Philip Cameron-Smith (Unlicensed) based on information from Mark Taylor and Kate Evans (Unlicensed), 2014-10-31 and Steve Goldhaber (Unlicensed) )
(NOTE: this capability has been expanded, and the namelist variables changed, so that old namelists will not work any longer )
The SE dycore runs on cubed-sphere grids (eg, NE30, NE120). The most accurate output is obviously on those native grids. However, plotting and analysis programs often only work with rectangular lat-lon output. And, ACME-CAM may not put all of the necessary information into the output files necessary for general plotting and analysis tools.
ACME is currently working on an interim has a solution that involves a regridding tool that regrids the ACME-CAM output files before reading them into UVCDAT: /wiki/spaces/WORKFLOW/pages/3245930
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This is setup in the user_nl_cam namelist, using the following namelist variables:
interpolateinterpolate_analysis output = .truefalse.,.truefalse.,.truefalse.,.truefalse.,.true.,.true.
interp_gridtype = 1 ! equal angle lat/lon grid, with point at pole (FV scalar grid)
interp_nlat=257 ! for
interpolate_nlon = 0, 0, 0, 0, 0, 128 ! Zero means select a resolution close to the native resolution.
interpolate_nlat = 0, 0, 0, 0, 0, 64
interpolate_type = 0, 0, 0, 0, 0, 1
interpolate_gridtype = 0, 0, 0, 0, 1, 2
To regrid a 1 deg atm run, the recommendation from Mark Taylor is to output onto a 0.7 deg grid (ie, 360 degrees / 512 points), slightly finer then the native 1.0 degree:
interp_nlat = 257 ! For a true equal angle grid, dimensions should be (N+1) x 2N
interpinterp_nlonnlon = 512
This example will cause CAM to output onto a .5 deg grid.interpolate_type = 1 ! 0 = native high order, 1 = bilinear (default)
interpolate_gridtype = 1 ! Equal angle lat/lon grid, with point at pole (FV scalar grid)
The options for the output grid type are:
interpinterpolate_gridtype = 1 equally 1 ! Equally spaced, including poles (FV scalars output grid) interp). Use grids of size (N+1) x 2N
interpolate_gridtype = 2 2 ! Gauss grid (CAM Eulerian) interp. Use grids of size N x 2N
interpolate_gridtype = 3 equally 3 ! Equally spaced, no poles (FV staggered velocity) Not Recommended
The interpolate_analysis options are for the different history tapes.
In the code there appears to also be There is also an option for the type of regridding:
interpinterpolate_type = 1 0 ! 0 0 = native high order, 1
interpolate_type = 1 ! 1 = bilinear (default)
is included in Notes on tuning 1 degree ACME v0 model
(Note: This regridding capabalitiy is included in /wiki/spaces/SIM/pages/7995515)