Re: regriding NARR data to T42 gird

From: Dennis Shea <shea_at_nyahnyahspammersnyahnyah>
Date: Sun, 13 Sep 2009 22:34:48 -0600

rcm2rgid finds the 4 NARR grid points that surround a T42 grid point.
These are the *only* points used to calculate the T42 value.
Given that the NARR is high resolution, the 4 nearest are
'pretty close' to the target T42 grid point.

If you want area averaging for cirvilinear grids [eg, NARR]
you could try


SCRIP is a software package which computes addresses and weights for
remapping and interpolating fields between grids in spherical
coordinates. It was written originally for remapping fields to other
grids in a coupled climate model, but is sufficiently general that it
can be used in other applications as well. The package should work for
any grid on the surface of a sphere. SCRIP currently supports four
remapping options:

     * Conservative remapping: First- and second-order conservative
remapping as described in Jones (1999, Monthly Weather Review, 127,
     * Bilinear interpolation: Slightly generalized to use a local
bilinear approximation (only logically-rectangular grids).
     * Bicubic interpolation: Similarly generalized (only
logically-rectangular grids).
     * Distance-weighted averaging: Inverse-distance-weighted average of
a user-specified number of nearest neighbor values.

SCRIP functionality has been included in the Earth System Modeling
Framework and the European PRISM framework.

area_hi2lores is written for rectilinear grids only.

Sanjiv Kumar wrote:
> Hello,
> I want to regird NARR data to T42 gird. I have succefully used the
> 'rcm2rgrid' for this purpose.
> However, since 'rcm2rgrid' simple inverse distance weighting, i am not
> quite sure about the interpolated values. Becuase NARR is a very high
> reolsution (32 km) data and T42 is very low resolution (~280 km) data.
> In my understanding 'area_hi2lores' would be more suitable function,
> becuase it uses area average method.
> See the attached pdf and excel for the explanation
> However first two argument 'xi' and 'yi' of 'area_hi2lores' should be
> one dimensaional and monotonically incresing that is not the case with
> NARR data.
> I was wondering how to overcome this issue.
> thanks
> sanjiv
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Received on Sun Sep 13 2009 - 22:34:48 MDT

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