Did you read the documentation for
http://www.ncl.ucar.edu/Document/Functions/Built-in/eofunc_varimax.shtml
and
http://www.ncl.ucar.edu/Document/Functions/Contributed/eofunc_varimax_reorder.shtml
[snip]
eof = eofunc_Wrap(x, neof, optEOF)
eof_ts = eofunc_ts_Wrap (x, eof, optETS)
printVarSummary( eof ) ; examine EOF variables
printVarSummary( eof_ts )
print("eof_ts: min="+min(eof_ts)+" max="+max(eof_ts) )
; =================================================================
; Perform varimax rotation
; =================================================================
eof_rot = eofunc_varimax_Wrap( eof, 1 )
printVarSummary( eof_rot )
print("eof_rot: min="+min(eof_rot)+" max="+max(eof_rot) )
; =================================================================
; put rotated EOFs into descending order (% variance explained)
; =================================================================
eofunc_varimax_reorder( eof_rot )
printVarSummary( eof_rot )
[snip]
The percent variance explained after rotation is returned as
the attribute 'pcvar_varimax'
On 11/8/12 8:10 PM, Waqar Younas wrote:
> Hi
> I have one more question about rotated EOFs.
> When i use the following loop to plot my rotated EOF with variance
> explained, it is not working for variance explained of rotated EOF. For
> example,
> do n=0,2-1
> res@gsnLeftString = "EOF "+(n+1)
> *res@gsnRightString = sprintf("%5.1f", eof@pcvar(n)) +"%"*
> plot(n)=gsn_csm_contour_map_polar(wks,ev_regres(n,:,:),res)
> end do
> gsn_panel(wks,plot,(/2,1/),resP) ; now draw as one plot
>
> This (res@gsnRightString = sprintf("%5.1f", eof@pcvar(n)) +"%") is
> variance explained by EOF instead of rotated EOF. When i modifiy this
> line by
> res@gsnRightString = sprintf("%5.1f", ev_rot@pcvar(n)) +"%", it gives me
> segmentation fault that pcvar is undefined variable or function. Here
> ev_rot are my rotated EOFs.
> Also, is there any difference between variance explained in EOF and
> rotated EOFs?
> Thanks in advance for help.
>
>
>
>
> On Tue, Nov 6, 2012 at 4:49 PM, Dennis Shea <shea@ucar.edu
> <mailto:shea@ucar.edu>> wrote:
>
> As noted in the eofunc_varimax documentation:
>
> "The results may be very dependent upon the user specified number of
> modes used in the rotation. The "best" number of modes to use may
> have to be determined by experiment."
>
> --
> Let's say the maximum possible number of eigenvalues/vectors is 1000.
> This means the 2nd EOF must be orthogonal to the 1st; the 3rd must
> be orthogonal to 1 and 2, etc. The orthogonality property impose
> constraints of the patterns.
>
> Even if you requested a subset of the eigen information, the LAPACK
> computes all the eigenvalues and returns just the subset but the
> full orthogonality is still in effect!
>
> If you use
> eof = eofunc(x,10, False)
> eofunc_varimax(eof)
>
> then the varimax imposes orthogonality on these 10 modes only.
>
> If you used only 2 modes .... then I'm not sure what you get
> but 2 modes in not 'right'
> eof = eofunc(x, 2, False)
> eofunc_varimax(eof)
>
>
>
>
>
>
> On 11/06/2012 03:00 PM, Waqar Younas wrote:
>
> Hi Phillips
> The data i used is NCEP/NCAP reanalysis of 500mb monthly
> geopotential
> height from 1950-2000.
> I got my results correct. The only confusion remaining is when i
> calculate only 2 rotational components the results are not
> exact, but
> when i calculate the 10 rotational components and plot only 2, the
> results are more like NAO (first component) and PNA (second
> component).
> Please find attached figure when i calculate 10 components and plot
> first 2 components. The other figure (when i calculate only 2
> components
> and plot them) is attached in the first message above. I do not
> know why
> there is such difference?
>
> Thanks.
>
>
>
> On Tue, Nov 6, 2012 at 1:29 PM, Adam Phillips <asphilli@ucar.edu
> <mailto:asphilli@ucar.edu>
> <mailto:asphilli@ucar.edu <mailto:asphilli@ucar.edu>>> wrote:
>
> Hi Waqar,
> Looking at your script, I don't see anything wrong. That
> leaves me
> trying to answer why the patterns are not what you expected
> them to
> be, and of course I cannot answer that. The patterns depend
> on the
> data you use. You can try running your script on other
> data, say,
> the NCEP/NCAR Reanalysis, to see if the results are what
> you expect.
> Good luck,
> Adam
>
>
> On 11/6/12 12:31 PM, Waqar Younas wrote:
>
> 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 <mailto:shea@ucar.edu>
> <mailto:shea@ucar.edu <mailto: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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>
>
>
> --
> 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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Received on Thu Nov 8 22:09:57 2012
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