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Re: Spherical gridding [message #35560 is a reply to message #35490]

Fri, 20 June 2003 11:06

hunter
Messages: 9
Registered: June 2003

Junior Member

Haje,

In the interest of completeness. I delved into griddata more thoroughly and,
of course, found that I had been a bit lax initially. Griddata works fine in
this application. Thanks for the pointer.

Interestingly, comparing the two resulting fields, one adhereing to
spherical coordinates and one approximating the sphere with cartesian
coordinates, the results are quite similar(using linear interpolation in
both cases). In fact, the difference in the resulting fields is, at most, 1%
of the minimm value of the original field. Typically, the difference is at
0.01%.

As for having "found a way around the physics", both methods generate
geometric approximations to a real field, not physical models. It just a
matter of establishing the error tolerances of the application.

Eli

"hunter" <elhunter@rci.rutgers.edu> wrote in message
news:3ef1d88d$1@rutgers.edu...
> I tried griddata using keywords for spherical gridding, but the results
were
> poor. However, assuming the lat lon coordinates were cartesian. gave a
much
> better representation of the data (visually).
>
> Eli
>
>
> "Haje Korth" <haje.korth@jhuapl.edu> wrote in message
> news:bcs8ba$24n$1@houston.jhuapl.edu...
>> I am using "griddata", which has been included with IDL since version
5.5.
>> It is much more powerful than sph_sct.
>>
>> Haje
>>
>>
>> --
>>
>> "Elias J. Hunter" <hunter@imcs.rutgers.edu> wrote in message
>> news:3EF0A470.1080008@imcs.rutgers.edu...
>>> Hello,
>>>
>>> I have a matrix of surface pressure north of 60N, that is currently on
a
>>> gaussian lat-lon grid. My goal is to interpolate this grid to a one
>>> degree by one degree lat-lon grid. Now when I attempt this using
>>> sph_sct, the field south of 75 degrees lat looks good, the grid north
of
>>> 75 degrees lat is a mess.
>>>
>>> My guess is that the longitudinal resolution north of 75 degrees on
the
>>> new grid is so fine relative to the old grid, its creating a problem.
I
>>> suppose it could also be becasue I'm getting closer to the singularity
>>> at the pole.
>>>
>>> Has anybody addressed a similar difficulty using sph_scat?
>>>
>>> Thanks,
>>> Eli
>>>
>>
>>
>
>

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[Message index]

		spherical gridding By: Sylvain Carette on Sun, 17 September 2000 00:00
		Re: Spherical gridding By: JD Smith on Thu, 19 June 2003 15:31
		Re: Spherical gridding By: Liam E. Gumley on Thu, 19 June 2003 12:17
		Re: Spherical gridding By: Liam E. Gumley on Thu, 19 June 2003 12:14
		Re: Spherical gridding By: Haje Korth on Thu, 19 June 2003 11:45
		Re: Spherical gridding By: Haje Korth on Thu, 19 June 2003 11:42
		Re: Spherical gridding By: Ben Tupper on Thu, 19 June 2003 10:11
		Re: Spherical gridding By: Paul Van Delst[1] on Thu, 19 June 2003 09:32
		Re: Spherical gridding By: Ben Tupper on Thu, 19 June 2003 09:14
		Re: Spherical gridding By: hunter on Thu, 19 June 2003 08:35
		Re: Spherical gridding By: hunter on Fri, 20 June 2003 11:06
		Re: Spherical gridding By: Liam E. Gumley on Thu, 19 June 2003 07:41
		Re: Spherical gridding By: Haje Korth on Thu, 19 June 2003 04:54
		Re: Spherical gridding By: wmconnolley on Wed, 18 June 2003 12:09

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