Re: Grid to grid interpolation (Correia, James)

From: Dennis Shea <shea_at_nyahnyahspammersnyahnyah>
Date: Mon, 18 May 2009 11:43:36 -0600

rcm2points finds the 4 grid points that surround the point to be
interpolated.
It uses an inverse square distance to determine the interpolated value.

I think that you might have to use the SCRIP sofware
http://climate.lanl.gov/Software/SCRIP/
[conservative remapping] to do what you want.

D

Seth McGinnis wrote:
> I have found it tolerably fast to use rcm2points in a loop over the x & y dimensions, calculating values for one gridcell at a time:
>
> do j = 0,ny-1
> do i = 0,nx-1
> lon = wrflon2d(j,i)
> lat = wrflat2d(j,i)
> temp = rcm2points(narrlat2d,narrlon2d,indata,lat,lon,1)
> outdata(:,j,i) = (/temp/)
> end do
> end do
>
> (I can't remember whether I decided to try looping to avoid memory problems with certain big files, or because it seemed easier than massaging the output back into the shape I wanted, or both, but it works.)
>
> I *think* rcm2points uses the same inverse distance weighting as linint2; I have no idea how it performs with regard to position errors.
>
> Cheers,
>
> --Seth McGinnis
>
>
>> Hi-
>> Does anyone have advice on interpolating from the NARR grid to a WRF grid
>> (both have 2d lat lon arrays)? What method would be pretty fast?
>>
>> Triple2grid won't do because I am concerned about even minor position errors
>> as I plan to do some validating of the wrf model dataset.
>> Linint2 does interpolation but not grid to grid.
>>
>> Thanks
>>
>> James Correia Jr., PhD
>> Climate Physics Group
>> Post. Doc.
>> Pacific Northwest National Lab
>>
>
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-- 
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Dennis J. Shea                  tel: 303-497-1361    |
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Received on Mon May 18 2009 - 11:43:36 MDT

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