[ncl-talk] A spatial band-pass filter

[Dennis Shea]

[1] I speculate the formula to which you refer applies to cartesian grids
and not grids on a sphere.

[2] Most commonly, filters are used on time series. However, they could be
applied to any series [Time, or space].

[3] NCL can perform spherical harmonic analysis/synthesis functions. So, if
you want spatial band pass filter on a sphere, you may wish to: (a)
perform a spherical harmonic analysis; (b) set the appropriate coefficients
to zero; and (c) perform a spherical harmonic syntheses. Technically, you
should do some form of tapering on the retained coefficients to minimize
Gibb's effects.

(b) is the tricky part
---
Good luck



On Fri, May 3, 2019 at 12:16 PM Prashanth Bhalachandran <
prashanth.bhalachandran at gmail.com> wrote:

> Hello NCL-experts,
> I am looking for a function that does a spatial band pass filtering
> (Gaussian low-pass filters). I checked for previous threads and I found
> that there are Lanczos filters in NCL. However, these appear to be specific
> to the temporal/frequency filtering (please correct me if I am wrong). I am
> looking for something spatial.
>
> Specifically, on the lines of:
>
> Any leads on this will be immensely helpful.
>
> Thank you,
> Prashanth
> _______________________________________________
> ncl-talk mailing list
> ncl-talk at ucar.edu
> List instructions, subscriber options, unsubscribe:
> http://mailman.ucar.edu/mailman/listinfo/ncl-talk
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.ucar.edu/pipermail/ncl-talk/attachments/20190503/ed73a794/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: Image 5-3-19 at 11.12 AM.jpg
Type: image/jpeg
Size: 112409 bytes
Desc: not available
URL: <http://mailman.ucar.edu/pipermail/ncl-talk/attachments/20190503/ed73a794/attachment.jpg>