Re: Regridding from low to high resolution ?

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.

On Sat, Jun 16, 2012 at 12:25 AM, Mary Haley <haley@ucar.edu> wrote:

> Hi Madeleine,
>
> Functions that you write yourself are the same as the other functions that
> you call, like grid2triple. You just need to make sure the function is
> defined before you call it.
>
> Here's a very basic and complete example of defining a function, and then
> calling it:
>
> undef("addten")
> function addten(x)
> begin
> y = x + 10
> return(y)
> end
>
> ;----Main code
> begin
> x = ispan(1,100,1)
> x10 = addten(x)
> print(x10)
> end
>
>
> ------------------------------------------------------------------------------------
>
> Here's what your partial script might look like, although I
> don't understand what "cnew" is supposed to be.
>
> 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"
>
> ;----------------------------------------------------------------------
> ; Define the regrid_cat function
> ;----------------------------------------------------------------------
> undef("regrid_cat")
> function regrid_cat(clat[*],clon[*],pctpft[*][*],tlat[*],tlon[*]) ;
> categorical grid and target grid
> local testd, pctpftnew, cnew ; using "local" is not required, but
> recommended
> begin
> testd = grid2triple(clon,clat,pctpft) ; testd(3,ld)
> pctpftnew = triple2grid(testd(0,:),testd(1,:),testd(2,:),tlon,tlat,False)
>
> copy_VarAtts(pctpft,pctpftnew) ;contributed.ncl
> ;
> ; I'm not sure what the "cnew" variable is,
> ; since it doesn't (and can't) get returned
> ; by this function
> ;
> cnew!0 = "lat"
> cnew!1 = "lon"
> cnew&lat =tlat
> cnew&lon =tlon
>
> return(pctpftnew)
> end
>
> ;----------------------------------------------------------------------
> ; This is the main code that will read in the data and call regrid_cat
> ;----------------------------------------------------------------------
> begin
>
> setfileoption("nc","SuppressClose",False)
> in1 = addfile("pft_file1.nc","r")
>
> pctpft = in1->PCT_PFT
>
> clat=90
> clon=144
> tlat=360
> tlon=720
> . . .
>
> xregrid = regrid_cat(clat,clon,pctpft,tlat,tlon)
>
> end
>
>
>
>
>
>
> On Jun 14, 2012, at 2:46 PM, Madeleine Patterson wrote:
>
> > Hi Mary,
> >
> > Sorry about the cluenessness about ncl-talk etiquette!
> >
> > I have set up the function declaration at the start of the code, before
> the main script, but am unsure of what I need to do to implement the
> function and where, in the main body of the script (i.e. after I've open
> files and read variables into variable names, etc.)
> >
> > In your example below, I would -after opening files and reading in
> variables -define clon, clat, tlon and tlat, but what do I do then? use the
> regrid_cat function that I've already defined (and if so, how?), as well as
> the 'testd=grid2triple()...' and 'pctpftnew=triple2grid()...' commands?
> >
> > In grid2triple command, 'z' should be 2-d, but in my case it is 3-d (10
> pfts, 91 lats, 144 lons)
> >
> > Is there an example script you could point me to that creates a function
> and implements it later in the script?
> >
> > Thanks,
> > M
> >
> > ******
> > You are missing a "begin" after the "function" declaration.
> >
> > In general, I would recommend not putting a function declaration right
> in the middle of your main program. It's cleaner to do it like this:
> >
> > 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[*],pctpft[*][*],tlat[*],tlon[*]) ;
> categorical grid and target grid
> > begin
> > testd=grid2triple(clon,clat,pctpft) ; testd(3,ld)
> > pctpftnew = triple2grid(testd(0,:),testd(1,:),testd(2,:),tlon,tlat,False)
> >
> > copy_VarAtts(pctpft,pctpftnew) ;contributed.ncl
> > cnew!0 = "lat"
> > cnew!1 = "lon"
> > cnew&lat =tlat
> > cnew&lon =tlon
> >
> > return(pctpftnew)
> > end
> >
> >
> > begin
> >
> > setfileoption("nc","SuppressClose",False)
> >
> > in1 = addfile("pft_file1.nc","r")
> >
> > pctpft = in1->PCT_PFT
> >
> > clat=90
> > clon=144
> > tlat=360
> > tlon=720
> > . . .
> >
> > end
> >
> >
> >
>
>

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Received on Fri Jun 15 10:24:13 2012