[ncl-talk] ESMF Regridding of WRF output files - issues on variable coordinates

[Mirce Morales]

Hello all,

I am trying to regrid some variables in my WRF output files (wrfout_d0*),
to do it, I am taking as a guide the following script on the NCL web page:
https://www.ncl.ucar.edu/Applications/Scripts/ESMF_regrid_20.ncl

Up to now, I was able to run the script without error, but I see that if I
do ncdump -h "My regridded file", there is like a matrix of numbers where
the XLAT and XLONG should be, so it is not possible to see the variables
and their attributes well....to avoid that, I found out I have to set
opt at CopyVarCoords  = False.

The problem is that when I do that, now I get the following kind of
attributes in my regridded files:

*netcdf wrfout_d03_2010-09-01_00\:00\:00 {*
*dimensions:*
*        ncl0 = 1 ;*
*        ncl1 = 156 ;*
*        ncl2 = 138 ;*
*        ncl3 = 1 ;*
*        ncl4 = 156 ;*
*        ncl5 = 138 ;*
*        ncl6 = 1 ;*
*        ncl7 = 156 ;*
*        ncl8 = 138 ;*
*        ncl9 = 1 ;*
*        ncl10 = 156 ;*
*        ncl11 = 138 ;*
*        ncl12 = 1 ;*
*        ncl13 = 156 ;*
*        ncl14 = 138 ;*
*        ncl15 = 1 ;*
*        ncl16 = 156 ;*
*        ncl17 = 138 ;*
*        ncl18 = 1 ;*
*        ncl19 = 156 ;*
*        ncl20 = 138 ;*
*        ncl21 = 1 ;*
*        ncl22 = 156 ;*
*        ncl23 = 138 ;*
*        ncl24 = 1 ;*
*        ncl25 = 156 ;*
*        ncl26 = 138 ;*
*        ncl27 = 1 ;*
*        ncl28 = 156 ;*
*        ncl29 = 138 ;*
*        ncl30 = 1 ;*
*        ncl31 = 156 ;*
*        ncl32 = 138 ;*
*variables:*
*        float T2(ncl0, ncl1, ncl2) ;*
*                T2:missing_value = 9.96921e+36f ;*
*                T2:remap = "remapped via ESMF_regrid_with_weights:
Bilinear" ;*
*                T2:_FillValue = 9.96921e+36f ;*
*                T2:FieldType = 104 ;*
*                T2:MemoryOrder = "XY " ;*
*                T2:description = "TEMP at 2 M" ;*
*                T2:units = "K" ;*
*                T2:stagger = "" ;*

When it should be similar to this:

*netcdf wrfout_d03_2010-09-01_01\:00\:00 {*
*dimensions:*
* Time = UNLIMITED ; // (1 currently)*
* DateStrLen = 19 ;*
* west_east = 54 ;*
* south_north = 60 ;*
* bottom_top = 49 ;*
* bottom_top_stag = 50 ;*
* soil_layers_stag = 4 ;*
* west_east_stag = 55 ;*
* south_north_stag = 61 ;*
*variables:*
*float T2(Time, south_north, west_east) ;*
* T2:FieldType = 104 ;*
* T2:MemoryOrder = "XY " ;*
* T2:description = "TEMP at 2 M" ;*
* T2:units = "K" ;*
* T2:stagger = "" ;*
* T2:coordinates = "XLONG XLAT XTIME" ;*

I don't know how to fix this....In case it helps, these are the regridding
options I am using:

*;---Open one WRF file *
*   sfile = addfile("../IMTAProy_BMJ/wrfout_d03_2010-10-31_16:00:00","r")
  ; contains source grid*

*;---Read lat/lon of source grid*
*    lat_src = sfile->XLAT(0,:,:)*
*    lon_src = sfile->XLONG(0,:,:)*

*;---Read lat/lon of destination grid*
*    lat_dst = dstfile->XLAT_M(0,:,:)*
*    lon_dst = dstfile->XLONG_M(0,:,:)*

*;---Options to pass to ESMF_regrid*

*    interp_method      = "bilinear"*
*    opt                        = True*

*    opt at SrcGridLat     = lat_src*
*    opt at SrcGridLon     = lon_src*
*    opt at DstGridLat     = lat_dst*
*    opt at DstGridLon     = lon_dst*

*    opt at SrcRegional    = True    ; Default is False*
*    opt at DstRegional    = True*

*    opt at CopyVarCoords  = False    ; This is the default in V6.1.0 (not
6.1.0-beta)*
*    opt at ForceOverwrite = True*

*;---Debug information*
*    opt at PrintTimings   = True*
*    opt at Debug          = True*

In summary, I have the following doubts:

1) How can I keep the coordinates of each variable in a proper way?
2) How can I keep the dimensions exactly as in my source files?
3) To create the weight files in a separate script, is there any template I
should base on for this case?
4) How can I add XLAT and XLONG in my regridded files like they are in the
original wrfout* files?...like this:

*variables:*
* char Times(Time, DateStrLen) ;*
* float XLAT(Time, south_north, west_east) ;*
* XLAT:FieldType = 104 ;*
* XLAT:MemoryOrder = "XY " ;*
* XLAT:description = "LATITUDE, SOUTH IS NEGATIVE" ;*
* XLAT:units = "degree_north" ;*
* XLAT:stagger = "" ;*
* XLAT:coordinates = "XLONG XLAT" ;*
* float XLONG(Time, south_north, west_east) ;*
* XLONG:FieldType = 104 ;*
* XLONG:MemoryOrder = "XY " ;*
* XLONG:description = "LONGITUDE, WEST IS NEGATIVE" ;*
* XLONG:units = "degree_east" ;*
* XLONG:stagger = "" ;*
* XLONG:coordinates = "XLONG XLAT" ;*

I will really appreciate any help/clue about this.

In case it is helpful my script and files are in the following path in
Cheyenne:

*/glade/scratch/mirce/LaSierra/FullDomainForcing/WRF/second_option*

If it would be better to paste here my the script I will be happy to do it!

Thanks a lot in advance!
Mirce.
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