[ncl-talk] ESMF regrid for large array data

[Anil Kumar - NOAA Affiliate]

Hi Dennis,
Thanks for getting back to me.
Opt at SrcGridCornerLat and Opt at SrcGridCornerLon points provided through WRF
max and min coordinates.
I don't know Is this way we can do it.
Src grid (Unstructured) is covering the Gulf and Atlantic and I want to
mask out the region where my wrf grid is located. For example WRF grid is
set up over the Houston Coastal region.
Is this correct?
Thanks

 dst_file = "../geo_em.d01.nc"  //WRF grid
 dfile    = addfile(dst_file,"r")


    dst_lat              = dfile->XLAT_M(0,:,:)    ; Be sure to use
appropriate names
    dst_lon              = dfile->XLONG_M(0,:,:)   ; here.

   Opt at SrcGridLat       = lat1D
    Opt at SrcGridLon       = lon1D
    Opt at SrcRegional      = True            ;;--Change (maybe)
    Opt at SrcInputFileName = src_file          ; optional, but good idea

    Opt at SrcGridCornerLat = (/ min(dst_lat),  max(dst_lat)/)
;sfile->lat_vertices    ; corners are necessary
    Opt at SrcGridCornerLon =  (/ min(dst_lon),  max(dst_lon)/)
 ;sfile->lon_vertices    ; for "conserve" method


On Mon, Mar 28, 2022 at 9:22 PM Dennis Shea <shea at ucar.edu> wrote:

> Given no responses, I speculate no user knows how to generate the edge
> vertices.
>
> *https://www.ncl.ucar.edu/Applications/ESMF.shtml*
> <https://www.ncl.ucar.edu/Applications/ESMF.shtml>
>
> Example 6 reads the vertices from a file.
>
> ESMF_regrid_6.ncl:    Opt at SrcGridCornerLat = sfile->lat_vertices    ;
> corners are necessary
> ESMF_regrid_6.ncl:    Opt at SrcGridCornerLon = sfile->lon_vertices    ; for
> "conserve" method
>
> ===
> The text above the examples contains:
>
> " You can (and are highly recommended to) provide your own grid corners
> via the special Src/Dst/GridCornerLat/Lon resources. They must be provided
> as an *N* x 4 array, where *N* represents the dimensionality of the
> center lat/lon grid. For example, if the center lat/lon grid is dimensioned
> 256 x 220, then the corner arrays must be 256 x 220 x 4. Sometimes the
> corner grids are provided on the file along with the center grids, with
> names like "lat_vertices"/"lon_vertices" or "lat_bounds"/"lon_bounds"."
>
> Good Luck
>
> On Wed, Mar 23, 2022 at 7:17 AM Anil Kumar - NOAA Affiliate via ncl-talk <
> ncl-talk at mailman.ucar.edu> wrote:
>
>> Hi All,
>> I am using ncl script for esmf regrid and converting unstructured onto
>> WRF grid.
>> There is nothing wrong with the script, it was working fine with the
>> previous unstructured grid nodes ( node = 1813443).
>> Now I am facing issues running these scripts for new unstructured data
>> nodes ( node = 6057307). It is taking a long time and CPU time terminates
>> the script and even job_script takes more than 8 hours and time limitation
>> issues with job_scripts.
>> Any suggestions to resolve this issue? Below is my script
>>
>> However, when I run script, it says
>>  This can be VERY slow if you have a large array.
>> (0)                           To speed up code, provide your own edge
>> vertices via the
>> (0)                           'ElementVertices' option.
>> How to use ElementVertices?
>>
>> *******************************************************
>>  src_file = "../fort.63.nc"
>>  sfile = addfile(src_file,"r")
>>  lat1D = sfile->y
>>  lon1D = sfile->x
>>  var = sfile->zeta(89,:)
>>
>>  dst_file = "../geo_em.d01.nc"
>>  dfile    = addfile(dst_file,"r")
>>   Opt                = True
>>
>> ;---"bilinear" is the default. "patch" and "conserve" are other options.
>>     Opt at InterpMethod     = "neareststod"        ;;---Change (maybe)
>>     Opt at WgtFileName      = "unstruct_to_rect_2906_D1.nc"
>>     Opt at SrcGridLat       = lat1D
>>    Opt at SrcGridLon       = lon1D
>>     Opt at SrcRegional      = False            ;;--Change (maybe)
>>     Opt at SrcInputFileName = src_file          ; optional, but good idea
>>
>>     Opt at SrcMask2D        = where(.not.ismissing(var),1,0) ; Necessary if
>> has
>>                                                           ; missing
>> values.
>>
>>     dst_lat              = dfile->XLAT_M(0,:,:)    ; Be sure to use
>> appropriate names
>>     dst_lon              = dfile->XLONG_M(0,:,:)   ; here.
>>     Opt at DstGridLon       = dst_lon
>>     Opt at DstGridLat       = dst_lat
>>     Opt at DstRegional      = True            ;;--Change (maybe)
>>     Opt at ForceOverwrite   = True
>>     Opt at Debug            = True
>>     Opt at PrintTimings     = True
>>     var_regrid = ESMF_regrid(var,Opt)     ; Do the regridding
>>     printVarSummary(var_regrid)
>>
>> --
>> Dr. Anil Kumar
>> Environmental Modeling Center/NCEP/NWS/NOAA
>> College Park, MD, USA
>>
>>
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>
>

-- 
Dr. Anil Kumar
Environmental Modeling Center/NCEP/NWS/NOAA
College Park, MD, USA
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