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

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

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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Received on Tue Nov 6 10:05:28 2012