Re: [ferret_users] eof_space problem?

To: "William.S.Kessler" <William.S.Kessler@xxxxxxxx>

Subject: Re: [ferret_users] eof_space problem?

From: lee lindsay <lindsayqd@xxxxxxxxx>

Date: Sun, 30 Mar 2008 15:31:01 -0500

Cc: ferret_users <ferret_users@xxxxxxxx>

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Hello, Billy,

The EOF1 amplitude is reversed, but the TAF1 is same as Matlab result, not reversed.

For example, we have high SST in 1998. By matlab results, the SST is high in 1998 and it is reasonalbe. By ferret first space and time mode, we got low SST in 1998?

Thanks,

Lindsay

2008/3/29, William.S.Kessler <William.S.Kessler@xxxxxxxx>:

Hi Lindsay -

EOF spatial and temporal functions can have either sign, as long as
the product EOF*Time Amplitude Function has the same sign. That is,
you can reverse the sign of EOF1, and should find the sign of TAF1
reversed as well. I think that must be what is happening here. Have
you checked the Time function against the matlab version? Is it also
reversed? In that case everything is copacetic. Note that you can
always multiply the EOF by (-1) (or any constant), as long as you
divide the TAF by the same constant.

Billy K

On 29/03/2008, at 7:47 PM, lee lindsay wrote:
> Hi, Ansley,
>
>
> I mean the amplitude multiplied by -1 in the first mode only. All
> the others is same, even the eof_stat shows exactly same percent. I
> only checked first two modes.
>
> My ferret version is 5.7.
>
>
> Here is the matlab eof package.
> http://hooimeijer-it.com/tudelft/Resources/Matlab_EOFs.html
>
> Thanks,
> Lindsay
>
>
> 2008/3/28, Ansley Manke <Ansley.B.Manke@xxxxxxxx>:
> Hi Lindsay,
> We haven't had any reports of this kind of trouble with the EOF
> functions. When you say the values show inverse, do you mean they are
> reversed north to south? or multiplied by -1?
>
> What version of Ferret are you running, and on what computer platform?
>
> Ansley
>
> lee lindsay wrote:
> >
> > Hello,
> >
> > I have tried to use "eof_space" by ferret and matlab EOF method. The
> > time series results are same by "eof_tfunc" and the second mode is
> > same. Although the spacial pattern results are similar in the first
> > mode , the values shows inverse. Does anyone know what's wrong on
> > that? Is it ferret wrong for the first mode spatical pattern?
> >
> > Thanks,
> > Lindsay
> >
> >
>