[ncl-talk] regridding

[Mary Haley]

Dear Igor,

We need a little more information.

First, it is helpful if you copy-and-paste the actual error message in your
email.

Second, please include the output from "printVarSummary(SLP)".

Really, though, it helps if you can provide the data files so we can run
the script and see what the issue is.

Thanks,

--Mary


On Thu, Feb 5, 2015 at 2:52 AM, igor akkerman <igorakkerman89 at gmail.com>
wrote:

> Hi,
>
> I need to regrid NCEP-NCAR reanalysis to a rotated regional model grid
> that is set up as follows:
>
> Sketch of the rotated grid (rot.lat, rot.lon)
> (24.5,-27.5) ------ (24.5,27.0)
>            |                         |
>            |                         |
> (-25.0,-27.5) ------ (-25.0,27.0)
> This is a regular grid with uniform resol. of 0.5.
>
> and in geograf. grid (geograf. lat, lon):
> (53.8,-134.6) ------ (54.2,135.1)
>            |                         |
>            |                         |
> (53.5,-44.7) ------ (53.85,44.2)
>
> I also have an ascii file with rotated grid cell coordinates and
> equivalent geographical coordinates called 'hirham_rot_geo_koor.dat".
>
> I tried making a script but can't correctly assign the conversion between
> rotated and geographical grid coordinates. Could you please take a look at
> the script and suggest how to fix it?
>
> The error message is that SLP_regrid variable has only one coordinate
> instead of three.
>
>
>   WRITE_NETCDF = False
>
> ; TEXT FILE CONVERTING ROTATED AND SPHERICAL LATS AND LONS
> filename = "hirham_rot_geo_koor.dat"
> coords = asciiread(filename,(/100,110,4/),"float")
> lat2d = coords(:,:,0) ; reading rotated latitude from ascii file
> lon2d = coords(:,:,1) ; reading rotated longitude from ascii file
> printMinMax(lon2d, True)
>
> ;---NCEP-NCAR reanalysis
>     srcFileName = "slp.1948.nc"
>     sfile = addfile(srcFileName,"r")
>
>     Opt                = True
>     Opt at SrcTitle       = "NCEP-NCAR reanalysis"   ; optional
>
>     Opt at WgtFileName    = "NCEP_to_Rect.nc"
>
>     Opt at ForceOverwrite = True
>
>     SLP = sfile->slp
>     SLP at lat2d = lat2d
>     SLP at lon2d = lon2d
>
> printVarSummary(SLP)
>
>     dims  = dimsizes(lat2d)
>     nlat  = dims(0)
>     nlon  = dims(1)
>
>     Opt at SrcFileName     = "Rectilinear.nc"      ; Name of source and
>     Opt at DstFileName     = "WRF_SCRIP.nc"    ; destination files
>
> ;---Create the destination lat/lon grid
>     printVarSummary(lat2d)
>     printVarSummary(lon2d)
>     printMinMax(lat2d, True)
>     printMinMax(lon2d, True)
>     lat = fspan( -25, 24.5,nlat)
>     lon = fspan( -27.5,27,nlon)
>     lat at units = "degrees_north"
>     lon at units = "degrees_east"
>     lat!0     = "lat"
>     lon!0     = "lon"
>     lat&lat   = lat
>     lon&lon   = lon
>
>     Opt at DstGridType          = "rectilinear"
>     Opt at DstGridLat           = lat
>     Opt at DstGridLon           = lon
>
>     Opt at InterpMethod         = "bilinear"
>     Opt at SrcRegional          = True
>     Opt at DstRegional          = True
>     Opt at Debug                = True
>     SLP_regrid = ESMF_regrid(SLP,Opt)     ; Do the regridding for TMP
> ;
> ; The source and destination grid description files and
> ; weight file will be the same for the next call to
> ; ESMF_grid, so no need to regenerate them.
> ;
>     Opt at SkipSrcGrid   = True
>     Opt at SkipDstGrid   = True
>     Opt at SkipWgtGen    = True
>
> ;---Reset 0 values to missing values.
>     SLP_regrid at _FillValue = default_fillvalue(typeof(SLP_regrid))
>
>     SLP_regrid            = where(SLP_regrid.eq.0.0,SLP_regrid@
> _FillValue,\
>                                   SLP_regrid)
>
>     printVarSummary(SLP_regrid)
>
> ;----------------------------------------------------------------------
> ; Plotting section
> ;
> ; This section creates filled contour plots of both the original
> ; data and the regridded data, and panels them.
> ;----------------------------------------------------------------------
>     wks_slp = gsn_open_wks("png","interpolate_slp")
>
>     res                       = True
>
>     res at gsnDraw               = False
>     res at gsnFrame              = False
>
>     res at cnFillOn              = True
>     res at cnLinesOn             = False
>     res at cnLineLabelsOn        = False
>     res at lbLabelBarOn          = False
>     res at cnLevelSelectionMode  = "ManualLevels"
>
>     res at gsnPolar              = "NH"
>     res at mpMinLatF             = min(lat)
>     res at gsnAddCyclic          = False
>
>     nrec      = 0
>     dims_orig = tostring(dimsizes(SLP(nrec,:,:)))
>
>     mnmxint_slp = nice_mnmxintvl( min(SLP), max(SLP), 18, False)
>
> ;---SLP
>     res at cnMinLevelValF  = mnmxint_slp(0)
>     res at cnMaxLevelValF  = mnmxint_slp(1)
>     res at cnLevelSpacingF = mnmxint_slp(2)/2.   ; Create more levels
>     res at tiMainFontHeightF = 0.015
>
> ;---SLP regridded
>     res at tiMainString  = "rectilinear grid (" + Opt at InterpMethod + "
> interpolation)"
>     slp_regrid = gsn_csm_contour_map(wks_slp,SLP_regrid(nrec,:,:),res)
>
> ;---SLP original
>     res at tiMainString = "SLP on original curvilinear grid (" +  \
>                         str_join(dims_orig," x ") + ")"
>
>     slp_orig = gsn_csm_contour_map(wks_slp,SLP(nrec,:,:),res)
>
> ;---Compare the plots in a panel
>     pres                   = True
>     pres at gsnMaximize       = True
>     pres at gsnPanelLabelBar  = True
>
>     gsn_panel(wks_slp,(/slp_orig,slp_regrid/),(/1,2/),pres)
>
> ;---Trim
>     system("convert -trim interpolate_slp.png interpolate.png")
>
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