[ncl-talk] Generating weights using ESMF_regrid_gen_weights

[Burakowski, Elizabeth]

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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