Re: curvilinear regridding

Matt,

Thanks for the files. There's no lat/lon information on the MM5 file. I do see a description of the map projection. Are the lat/lon values supposed to be generated from this?
If so, it would help if you could provide some information on this.

--Mary

On Jun 19, 2012, at 10:26 AM, Matthew Fearon wrote:

> Hi Mary,
>
> Thank you. This is exactly what I need. I placed 2 netcdf files on an anonymous ftp
>
> 1. raw wrf file: wrfout_d03_2012-04-22_23:00:00.nc
> 2. processed mm5 file: 2010-04-30-12.nc
>
> ftp://pubfiles.dri.edu/pub/mfearon/
>
> Spatially, file 2 is a sub-domain of file 1. My plan is to align corresponding variables from file 1 to those in file 2. Please let me know if you have any questions about the files as you have time to work with them. Thank you again for your assistance.
>
> Matt
>
>
> ----- Original Message -----
> From: Mary Haley <haley@ucar.edu>
> Date: Tuesday, June 19, 2012 8:02 am
> Subject: Re: curvilinear regridding
> To: Matthew Fearon <Matthew.Fearon@dri.edu>
> Cc: ncl-talk@ucar.edu
>
>
> > Hi Matt,
>
>
> > In Version 6.1.0-beta of NCL, we have some new ESMF regridding routines that allow you to go from rectilinear, curvilinear, or unstructured grids, to any one of these three grids.
> > You should be able to use this software to go from a curvilinear grid to a curvilinear grid.
> >
> > Here's a code snippet of what the regridding might look like. I'm assuming that the file that contains the "source" WRF grid is called "wrf_output.nc", and that the curvilinear lat/lon grid on the file is called "XLAT" and "XLONG". I'm also assuming XLAT and XLONG are 3D, so I'm just grabbing the first time step of both.
> >
> > Finally, I'm assuming that the "destination" MM5 grid is on a file called "mm5_grid.nc" and that the curvilinear lat/lon variables are simply called "lat" and "lon":
> >
> > ;---Read the source and destination lat/lon grids
> > srcFileName = "wrf_output.nc"
> > dstFileName = "mm5_grid.nc"
> >
> > sfile = addfile(srcFileName,"r")
> > dfile = addfile(dstFileName,"r")
> >
> > src_lat = sfile->XLAT(0,:,:)
> > src_lon = sfile->XLON(0,:,:)
> > dst_lat = dfile->lat
> > dst_lon = dfile->lon
> >
> > ;---Read the data you want to regrid
> > x = sfile->x
> >
> > ;---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
> > ;
> > ; If you run the script multiple times, then the three
> > ; NetCDF files that get written (source description
> > ; file, destination description file, and weights file)
> > ; will be overwritten without any prompting.
> > ;
> > Opt@ForceOverwrite = True
> >
> > Opt@CopyVarCoords = True ; Whether to copy coordinate information
> > ; to regridded variable
> >
> > Opt@InterpMethod = "bilinear" ; (default) "patch" or "conserve"
> >
> > xregrid = ESMF_regrid(x,Opt) ; Regrid "x" to new grid
> >
> >
> > If you are able to provide me with a sample of both grids, I would be happy to add an example to our ESMF regridding page:
> >
> > http://www.ncl.ucar.edu/Applications/ESMF.shtml
> >
> > Cheers,
> >
> > --Mary
> >
> > On Jun 19, 2012, at 8:44 AM, Matthew Fearon wrote:
> >
>> > Dear NCL users:
>> >
>> > I'm working with both older MM5 output and more recent WRF for an overlapping spatial domain. I would like to aggregate / regrid WRF output to the MM5 grid, 2km to 4km, respectively. Is there a pre-written tool in NCL to do this? I see there's options for going from curvilinear to rectilinear and vice versa, but not curvilinear to curvilinear?
>> >
>> > Suggestions would be very helpful, thanks,
>> > Matt
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Received on Tue Jun 19 15:04:17 2012