; Script for regridding from WRF curvelinear grid to rectlinear grid of gpm data

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" 

begin

;---Read the source and destination lat/lon grids
 
    srcFileName = "wrf.nc" 
    dstFileName = "precip.nc" 
    sfile = addfile(srcFileName,"r") 
    dfile = addfile(dstFileName,"r") 
    src_lat = sfile->XLAT(8,:,:) 
    src_lon = sfile->XLONG(8,:,:) 
    dst_lat = dfile->lat 
    dst_lon = dfile->lon 

;---Read the data you want to regrid 
    r1 = sfile->RAINNC
    r2 = sfile->RAINC
    rain = r1 + r2
 
;---Options for regridding 
    Opt = True 

;---source grid information 
    Opt@SrcRegional = True 
    Opt@SrcGridLat = src_lat 
    Opt@SrcGridLon = src_lon 

;---destination grid information 
    Opt@DstRegional = True 
    Opt@DstGridLat = dst_lat 
    Opt@DstGridLon = dst_lon 
 
    Opt@ForceOverwrite = True 
    Opt@CopyVarCoords = True ; Whether to copy coordinate information 
                                 ; to regridded variable 
    Opt@InterpMethod = "bilinear" ; (default) "patch" or "conserve" 
    
   raingrid = ESMF_regrid(rain,Opt) ; Regrid "rain" to new grid 

end