Re: Regridding from low to high resolution ?

Hi Mary,

This is really great - thank you so much for helping me to finally solve
this problem! I really appreciate the effort that you and other NCL experts
have made to help myself and others solve our NCL problems!

I have a couple of follow-up questions - one relates to writing out the
regridded variable:

I have added between the 'end do' and final 'end' of your script, the lines

system("/bin/rm -f fpcgrid0pt5x0pt5.nc") ; remove any pre-existing file
ncdf = addfile("fpcgrid0pt5x0pt5.nc",
"c") ; open and create netcdf file
ncdf->FPCGRID = var_regrid(:,:,:)

Which works fine - I output my netcdf file (editing your script to only
output one variable at a time), except that I'm getting a lot of
underscores i.e. in a ncdump of the output file:

 FPCGRID =
  _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _,
_,
    _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _,
    _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _,
    _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _,

- do these represent missing values? If they do, how would I change these
to 0's? (I tried the "var_regrid@_FillValue = 0." before writing the
variable into the netcdf file, but it doesn't work)... I checked the
original-unregridded file and it too has these underscores, except I will
be feeding the regridded file into another model and I don't think it's
going to like the underscores....

 Also, is there a way to reduce the number of decimal points of the output
values (since they're percentages...)

Thanks again!!

M.P.

On Mon, Jul 16, 2012 at 5:31 AM, Madeleine Patterson <
madeleine.patterson77@gmail.com> wrote:

> Hi Mary,
>
> This is really great - thank you so much for helping me to finally solve
> this problem! I really appreciate the effort that you and other NCL experts
> have made to help myself and others solve our NCL problems!
>
> I have a couple of follow-up questions - one relates to writing out the
> regridded variable:
>
> I have added between the 'end do' and final 'end' of your script, the lines
>
> system("/bin/rm -f fpcgrid0pt5x0pt5.nc") ; remove any pre-existing file
> ncdf = addfile("fpcgrid0pt5x0pt5.nc","c") ; open and create netcdf file
> ncdf->FPCGRID = var_regrid(:,:,:)
>
> Which works fine - I output my netcdf file (editing your script to only
> output one variable at a time), except that I'm getting a lot of
> underscores i.e. in a ncdump of the output file:
>
> FPCGRID =
> _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _,
> _,
> _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _,
> _,
> _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _,
> _,
> _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _,
> _,
>
> - do these represent missing values? If they do, how would I change these
> to 0's? (I tried the "var_regrid@_FillValue = 0." before writing the
> variable into the netcdf file, but it doesn't work)... I checked the
> original-unregridded file and it too has these underscores, except I will
> be feeding the regridded file into another model and I don't think it's
> going to like the underscores....
>
> Also, is there a way to reduce the number of decimal points of the output
> values (since they're percentages...)
>
> Thanks again!!
>
> M.P.
>
>
>
> On Sat, Jul 14, 2012 at 6:25 AM, Mary Haley <haley@ucar.edu> wrote:
>
>> Hi Madeleine,
>>
>> I'm posting this back to ncl-talk, so they can see how we resolved this
>> issue.
>>
>> Please see the attached script, which requires V6.1.0-beta in order to
>> run. This script regrids several variables (I picked them at random, but
>> made the first one "FPCGRID") using the ESMF_regrid function.
>>
>> I've included the plot of the FPCGRID variable only.
>>
>> The main regridding function in this script is called "regrid_variable".
>> The first time you regrid something, it generates 3 NetCDF files (a source
>> description file, a destination description file, and a weights file). For
>> regridding other variables from and to the same grid, you don't need to
>> keep regenerating these three files. That's why I have the "SkipSteps"
>> variable. It will skip those three steps for subsequent variables.
>>
>> In the regrid_variable function, I have to "fix" the latitude values so
>> they are not missing. Otherwise, you will get errors when you try to plot
>> it. Also, at least one of your variables (PFT) had a _FillValue attribute
>> of 9999, which I believe is supposed to be -9999. If you regrid this
>> variable, you will have to fix the _FillValue (I have a check for this in
>> the attached script).
>>
>> --Mary
>>
>>
>>
>> On Jul 9, 2012, at 10:10 AM, Mary Haley wrote:
>>
>> > Madeleine,
>> >
>> > I don't understand something about your script. You are setting clat
>> and clon to scalar values, and then using these in the grid2triple routine.
>> Are you really trying to regrid only one value at a time?
>> >
>> > grid2triple is expecting the first two arguments to be arrays of
>> lat,llon values of size nlat and nlon. The third argument to grid2triple,
>> then, should be an nlat x long array whose coordinates are represented by
>> the lat and lon arrays.
>> >
>> > You are giving it a 2D array to regrid, but only one longitude and one
>> latitude value. That's why it's giving you an error.
>> >
>> > I might be able to help you with the regridding issue, using our new
>> ESMF regridding capabilities. Can you give me your full script and data,
>> and a detailed explanation of what you are trying to regrid? Do you have
>> V6.1.0-beta installed?
>> >
>> > --Mary
>> >
>> >
>> > On Jul 8, 2012, at 6:29 PM, Madeleine Patterson wrote:
>> >
>> >> Hi,
>> >>
>> >> I tried respecifying it to have 3 dimensions (pctpftN[*][*][*]), took
>> out the do loops, but am still getting error messages - it seems that the
>> grid2triple function cant handle 3 dimensions (which I guess should be
>> apparent from it's name...)
>> >>
>> >> fatal:Number of dimensions in parameter (2) of (grid2triple) is (3),
>> (2) dimensions were expected
>> >> fatal:Execute: Error occurred at or near line 27 in file changedims.ncl
>> >>
>> >> ...If I use do loops to try to use grid2triple with a 3rd dimension, I
>> get an error:
>> >>
>> >> fatal:grid2triple: The last input array must be dimensioned ny x mx,
>> where ny is the length of y, and mx is the length of x
>> >>
>> >> So, I can't get it to work.... seems I may not be able to regrid my
>> categorical data this way...
>> >>
>> >>
>> >>
>> >>
>> >> On Sat, Jul 7, 2012 at 5:46 AM, Hobbs, Will R (3244-Affiliate) <
>> William.R.Hobbs@jpl.nasa.gov> wrote:
>> >> Madeleine
>> >>
>> >> In your argument for the function regrid_cat(), you specify the input
>> variable pctpftN as having two dimensions (i.e. pctpftN[*][*]).
>> >>
>> >> Hope that helps
>> >>
>> >> Will
>> >>
>> >> **********************************************************
>> >> Will Hobbs, Ph.D. William.R.Hobbs@jpl.nasa.gov
>> >> Jet Propulsion Laboratory
>> >> 4800 Oak Grove Dr. office: 300-324a
>> >> M/S 300-323 phone: (818) 354-0466
>> >> Pasadena, CA 91109 fax: (818) 354-0966
>> >> **********************************************************
>> >>
>> >> From: Madeleine Patterson <madeleine.patterson77@gmail.com>
>> >> Date: Sat, 7 Jul 2012 05:40:57 +1000
>> >> To: ncl-talk <ncl-talk@ucar.edu>
>> >>
>> >> Subject: Re: Regridding from low to high resolution ?
>> >>
>> >> Hi,
>> >> I am still trying to implement some script ideas that Mary Haley
>> suggested I try in order to regrid categorical data from low to high
>> resolution, but I cannot get the grid2triple() function -which I'm using to
>> create a regrid function, let alone the actual regrid function - to work
>> with 3 dimensions of data -even with do loops... I keep getting error
>> messages telling me it's expecting 2 dims when I'm giving it 3:
>> >>
>> >> fatal:Number of subscripts do not match number of dimensions of
>> variable,(3) Subscripts used, (2) Subscripts expected
>> >> fatal:Execute: Error occurred at or near line 23 in file changedims.ncl
>> >> fatal:Execute: Error occurred at or near line 75 in file changedims.ncl
>> >>
>> >> I am wondering if I am implementing the do loop with the wrong syntax,
>> or if there is something else wrong with my script (below)?
>> >> Can anyone suggest a way to get grid2triple to work with a 3D input
>> dataset?
>> >>
>> >> Thanks for your advice...
>> >>
>> >> MP
>> >>
>> >>
>> ********************************************************************************
>> >> 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/csm/shea_util.ncl"
>> >>
>> >> undef("regrid_cat")
>> >> function regrid_cat(clat[*],clon[*],pctpftN[*][*],tlat[*],tlon[*])
>> ; categorical grid and target grid
>> >> local testd, pctpftNnew
>> >>
>> >> begin
>> >>
>> >> do i=1,10
>> >> testd=grid2triple(clon,clat,pctpftN(i,:,:)) ; testd(3,ld)
>> >> end do
>> >>
>> >> pctpftNnew =
>> triple2grid(testd(0,:),testd(1,:),testd(2,:),tlon,tlat,False)
>> >> copy_VarAtts(pctpftN,pctpftNnew) ;contributed.ncl
>> >> return(pctpftNnew)
>> >>
>> >> end
>> >>
>> ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
>> >> ; main code
>> >>
>> ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
>> >> begin
>> >>
>> >> in1 = addfile("pctpft.nc","r")
>> >> pctpft = in1->PCTPFT
>> >> pctpftN = pctpft(0,:,:,:)
>> >>
>> >> printVarSummary(pctpftN)
>> >>
>> >> clat=90
>> >> clon=144
>> >> tlat=360
>> >> tlon=720
>> >>
>> >> ntim =dimsizes(pctpftN(:,0,0))
>> >> nlat =dimsizes(tlat)
>> >> nlon = dimsizes(tlon)
>> >>
>> >> pctpftNnew=new((/ntim,nlat,nlon/),typeof(pctpftN))
>> >> ;pctpft_regrid=new((/ntim,nlat,nlon/),typeof(pctpftN))
>> >>
>> >> do i=0,ntim-1
>> >>
>> >> pctpftNnew(i,:,:) = regrid_cat(clat,clon,pctpftN(i,:,:),tlat,tlon)
>> ; categorical grid and target grid
>> >>
>> >> end do
>> >>
>> >> end
>> >>
>> ********************************************************************************
>> >>
>> >> On Tue, Jun 19, 2012 at 2:33 AM, Mary Haley <haley@ucar.edu> wrote:
>> >> Hi Madeleine,
>> >>
>> >> You will need to add a "do" loop and call grid2triple for each element
>> of that third dimension. I'm not sure why grid2triple doesn't allow for
>> multiple leftmost dimensions. I'll look into this.
>> >>
>> >> Meanwhile, maybe something like this:
>> >>
>> >> ntim = dimsizes(pctpft(:,0,0))
>> >> nlat = dimsizes(tlat)
>> >> nlon = dimsizes(tlon)
>> >>
>> >> xregrid = new( (/ntim,nlat,nlon/), typeof(pctpft))
>> >>
>> >> do i=0,ntim-1
>> >> xregrid(i,:,:) = regrid_cat(clon,clat,pctpft(i,:,:),tlat,tlon)
>> >> end do
>> >>
>> >> I don't know what "regrid_cat" looks like, so I'm not sure this is the
>> correct syntax. Perhaps the creation of "xregrid" and the "do" loop should
>> be moved into "regrid_cat".
>> >>
>> >> --Mary
>> >>
>> >> On Jun 15, 2012, at 10:23 AM, Madeleine Patterson wrote:
>> >>
>> >>> Hi Mary,
>> >>>
>> >>> Thanks for your response - I am trying to get the regridding function
>> I created to work; I've tried your code but I get an error message:
>> >>>
>> >>> fatal: number of dimensions in parameter (2) or (regrid_cat) is (3),
>> (2) dimensions were expected
>> >>>
>> >>> So I tried putting the regrid function into a do loop so I can loop
>> over all 10 pfts...
>> >>>
>> >>> do i=1,10
>> >>> xregrid = regrid_cat(clon,clat,pctpft(i,:,:),tlat,tlon) ;;;; (this
>> may well be incorrect syntax)
>> >>> end do
>> >>>
>> >>> but then I get the error message :
>> >>>
>> >>> fatal: grid2triple : the last input array must be dimensioned ny x mx
>> where ny is the length of y and mx is the length of x
>> >>>
>> >>> - so in my function definition testd=grid2triple(clon,clat,pctpft),
>> it's saying pctpft must be 2 dimensional, not 3 dimensional (which it is).
>> >>>
>> >>> How to get around this? Would I have to read in each pft as one 2d
>> variable, perform the regridding then reconstruct the 3d netcdf file, or is
>> there an easier solution?
>> >>>
>> >>> thanks,
>> >>>
>> >>> M.P.
>> >>
>> >>
>> >>
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>>
>>
>

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Received on Sun Jul 15 13:33:05 2012