Re: About Rotated EOF patterns of NCEP reanalysis 500mb monthly data

Hi
It does not make any difference because even without reordering, i was
getting the EOF patterns in order as first mode explained variance was
13.3% and second one is 10% and so on. The patterns did not change.
I do not know where i am making mistake because especially for PNA, the
most variance should be in Western side but my PNA pattern is capturing
variability on Eastern side too. Now i am attaching the whole code which i
modified using eof_4.ncl.
Thanks.

On Tue, Nov 6, 2012 at 9:05 AM, Dennis Shea <shea@ucar.edu> wrote:

> The documentation for eofunc_varimax includes the following
>
> " The order of the returned varimax rotated EOFs is not necessarily in
> strict descending order as returned by eofunc or eofunc_varimax_Wrap. The
> user should use the *eofunc_varimax_reorder* procedure to place the
> returned varimax rotated EOFs into strict descending order."
>
> http://www.ncl.ucar.edu/**Document/Functions/**Contributed/eofunc_varimax_
> **reorder.shtml<http://www.ncl.ucar.edu/Document/Functions/Contributed/eofunc_varimax_reorder.shtml>
>
> It seems to me you should have"
>
> ev_rot = eofunc_varimax_Wrap(eof,1)
> printVarSummary(ev_rot)
>
> eofunc_varimax_reorder(ev_rot)
> printVarSummary(ev_rot)
>
> ; ev_rot will be orthogonal. However, 'ev_rot1'
> ; will not tield principal components that are independent
>
>
>
> ev_rot1 = eofunc_ts_Wrap (wx, ev_rot, optETS)
>
>
> On 11/05/2012 06:23 PM, Waqar Younas wrote:
>
>> Hi all,
>> I need help in performing the rotated EOF of NCEP/NCAR reanalysis data
>> using NCL. I used the code eof_4.ncl present on ncl functions page. This
>> code use the same data i.e. 500mb monthly data set from NCEP/NCAR from
>> 20S to 90S but this code only calculates the EOF. This code is
>> originally written for calculating AAO oscillations.
>> For my case, i change the region from 20-90 N and for rotated EOF, i
>> added these lines in the code
>>
>> ;;;;;;; Rotation of EOF
>>
>> ev_rot = eofunc_varimax_Wrap(eof,1)
>> printVarSummary(ev_rot)
>> ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;**;;;;;;;;;;;;;;;;;;;;
>> ev_rot1 = eofunc_ts_Wrap (wx, ev_rot, optETS)
>> ev_rot1 = dim_standardize_n( ev_rot1, 0, 1)
>> ; ==============================**==============================**=====
>> ; Regress
>> ; ==============================**==============================**=====
>> ev_regres = ev_rot ; create an array w
>> meta data
>> do ne=0,neof-1
>> ev_regres(ne,:,:) = (/ regCoef(ev_rot1(ne,:),
>> xAnom(lat|:,lon|:,time|:)) /)
>> end do
>> At the end, i plot this ev_regres which contains REOF1 and REOF2.
>> According to many papers and definitions of Climate prediction centre,
>> the first REOF should be NAO and second should be PNA. In my case, the
>> first EOF is NAO but it is slightly different. The second EOF is
>> capturing PNA but it is not exact. I am attaching the figure.
>> For my research i need PNA pattern which is second REOF. It is capturing
>> PNA but also some other variabilties too.
>> Thanks for the help in advance.
>>
>>
>>
>>
>>
>> --
>> Best Regards
>>
>> Waqar Younas
>> PhD Candidate
>> Natural Resources and Environmental Studies (NRES)
>> University of Northern British Columbia (UNBC)
>> Canada
>>
>>
>>
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>>
>>
>

-- 
Best Regards
Waqar Younas
PhD Candidate
Natural Resources and Environmental Studies (NRES)
University of Northern British Columbia (UNBC)
Canada

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