Re: EOF signs

From: Wei Huang <huangwei_at_nyahnyahspammersnyahnyah>
Date: Wed, 9 Sep 2009 08:28:28 -0600


There is no way to have the EOFs automatically
give the same sign. The EOFs are calculated using
LAPACK's "dspevx" routine.

If there is a location in space that you want a
particular sign, you could test that point and
change the sign accordingly.


Wei Huang
National Center for Atmospheric Research
P.O. Box 3000 (1850 Table Mesa Dr.)
Boulder, CO 80307-3000 USA
(303) 497-8924

On Sep 9, 2009, at 7:44 AM, Aideen Foley wrote:

> Hello.
> I am applying the same EOF analysis script to output from different
> climate models, and finding that for some datasets, the primary EOF
> is positive, and for others it is negative, with a time amplitude
> series that is the inverse of what I would expect were it positive.
> I know that that one can multiply the EOF and it's time amplitude
> series by -1 to aid interpretation, but I would like to understand
> why the eofunc routine prefers inverted output for some of my data
> but not for others. I would like if it followed the same convention
> with each. dataset. Can anyone help me with this question?
> Many thanks,
> Aideen Foley
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Received on Wed Sep 09 2009 - 08:28:28 MDT

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