[ncl-talk] Generating weights using ESMF_regrid_gen_weights

[Dennis Shea]

I have not looked carefully at this.

[1]
*The SWE variable is type short. *

*short *SWE(time, lat, lon) ;
SWE:_FillValue = -999s ;
SWE:long_name = "Snow Water Equivalent" ;
SWE:grid_mapping = "crs" ;
SWE:units = "millimeters h20" ;

*You *must* unpack before use.*

swe = *short2flt*
<https://www.ncl.ucar.edu/Document/Functions/Contributed/short2flt.shtml>
(sfile->SWE)
or, for a focused regional subset
swe = *short2flt*(sfile->SWE({latS:latN},{lonW:lonE}))

===
[2]
*ncremap* is a netCDF Operator. It looks like you want the weights
generated by NCL's *ESMF *regrid package.
Are the weight files compatible?

===

D


On Mon, Nov 25, 2019 at 2:35 PM Burakowski, Elizabeth via ncl-talk <
ncl-talk at ucar.edu> wrote:

> I'm attempting to generate weights for regridding a 4 km grid to a 14 km
> grid using ESMF_regrid_gen_weights.
>
> Source grid:
> Univ. Arizon Snow Depth and SWE grids
> 4 km rectilinear, [lat | 621] x [lon |1405]
>
> Destination grid:
> VR-CESM CONUS (already regridded using ESMF)
> 14 km rectilinear, [lat | 361] x [lon |560]
>
> In the below NCL script, I use rectilinear_to_SCRIP on source and
> destination grids, then ESMF_regrid_gen_weights to create the weight file.
> No errors occur, however, when I try to regrid using ncremap, I get a bunch
> of zeros. I'd like to use the weight file on hundreds of files, hence using
> ncremap.
>
> When I test the weight file on one source variable using NCL's
> ESMF_regrid_with_weights, I get an argument type mismatch error, but I
> can't figure out why.  Any ideas how to fix this? Files are on cheyenne.
>
> Script to generate weights:
>
> ;======================================================================
> ; ESMF Regrid:   UA-SNOW-4km (rectilinear) to VRCESM-CONUS (rectilinear)
> ;======================================================================
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl"
> load "$NCARG_ROOT/lib/ncarg/nclscripts/esmf/ESMF_regridding.ncl"
>
> ;======================================================================
> ;                         The main code
> ;======================================================================
>
> begin
> ;---Specify interpolation to be used
>     method = "patch"
>
> ;---Specify weight file name
>     wgtFileName = "UASnow4km2VRCESMCONUS14km_"+method+".nc"
>
> ;---Input file (Source)
>     srcFileDir  = "/glade/work/burakows/plot/validation/UA_Snow_4km/"
>     srcFileName = "4km_SWE_Depth_WY2014_v01.nc"       ; any UA-Snow file
>     srcGridName = "UASnow_4km_SCRIP.nc"
>
> ;---Retrieve a sample variable (used in plot)
>     sfile       = addfile(srcFileDir+srcFileName,"r")
>     srcVarName  = "SWE"                                ; [lat | 621] x [x
> | 1405]
>     var_in      = sfile->$srcVarName$
>     printVarSummary(var_in)
>
>     Opt                 = True
>     Opt at ForceOverwrite  = True
>     Opt at Title           = "UA Snow 4km Grid"
>
> ;--- Convert UA Snow 4 km grid to SCRIP convention file
>     rectilinear_to_SCRIP(srcGridName,var_in&lat,var_in&lon,Opt)
>     delete(Opt)
>
> ;================================================================
>
> ;---File that contains the destination file coordinates
>     dstFileDir  =
> "/glade/scratch/burakows/archive/VR-CESM_FHISTSTUB.1984-2015.CONUS30x4_prod/lnd/remap/"
>     dstFileName = "
> VR-CESM_FHISTSTUB.1984-2015.CONUS30x4_prod.clm2.h0.2014-01-01-00000_regrid.nc"
>  ; any VR-CESM file
>     dstGridName = "VRCESMCONUS_14km_SCRIP.nc"
>
> ;---open VR-CESM file that contains the VR-CESM grid coordinates
>     dfile       = addfile(dstFileDir+dstFileName,"r")
>     dstVarName  = "H2OSNO"
>     dvar_in     = dfile->$dstVarName$           ; [lat | 361 ] x [lon |
> 560]
>     printVarSummary(dvar_in)
>
>     Opt                 = True
>     Opt at ForceOverwrite  = True
>     Opt at Title           = "VR-CESM CONUS (14 km) grid"
>
> ;--- Convert VR-CESM CONUS 14 km to SCRIP convention file
>     rectilinear_to_SCRIP(dstGridName,dvar_in&lat,dvar_in&lon,Opt)
>     delete(Opt)
>
> ;--- Generate the weights to convert UA Snow 4 km grid to VR-CESM CONUS 14
> km grid
>
>     Opt         = True
>     Opt at InterpMethod    = "patch"
>     Opt at ForceOverwrite  = "True"
>
>     ESMF_regrid_gen_weights(srcGridName,dstGridName,wgtFileName,Opt)
>     delete(Opt)
> end
>
> ;===============================================================
>
>
> Dr. Elizabeth A Burakowski
> She/Her/Hers
> Research Assistant Professor
> Earth Systems Research Center &
> Institute for the Study of Earth, Oceans, and Space
> University of New Hampshire
> 8 College Road Durham, NH 03824
> 603-862-1796
> elizabeth.burakowski at unh.edu
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