[ncl-talk] EOF Reconstruction of mode 2 larger than mode 1

Fri Dec 15 02:52:46 MST 2017

```Hello all,

I input omega data(time, lev, lat, lon) and do EOF for every grid
point to get characteristic vertical structure of omega.

I used eofunc to get 3 modes of eigenvectors.

However, I met a problem, when I reconstructed mode 1(w1) and mode 2 (w2).

I tested 3 grid points and compared reconstructed omega and original omega.

grid 1 : 0N, 150E in western Pacific

grid 2 : 10N, 120W in eastern Pacific

grid 3 : 10S, 110W in eastern Pacific cold tongue

Result in grid 1 & 2 match my intuition. w1 >w2

However, result in grid 3 against my intuition. w2>w1

After examining data, I found ts_mean of mode 2 larger then mode 1 so
that w2 larger than w1.

I attached my code for EOF reconstruction below.

Is there anything wrong with my conceptions or coding process?

Thanks for help!

do mode = 0, 2

w_re = new((/nSeason,klev,nlat,mlon/),float,msg_val)
w_re = 0.
dimName = (/"time", "plev", "lat", "lon"/)
do dim = 0, 3
w_re!dim = dimName(dim)
if (dim .ne. 0) then
w_re&\$dimName(dim)\$ = w_eof&\$dimName(dim)\$
end if
end do
do i = 0, nlat-1
do j = 0, mlon-1
do time = 0, nSeason-1
if (num(ismissing(w_eof(mode,:,i,j))) .le. 5) then
w_re(time,:,i,j) =
w_eof(mode,:,i,j)*(w_ts(mode,time,i,j) + w_ts_mean(mode,i,j))
end if
end do
end do
end do

--

-------------------
Rung-Ying, Su
Department of Atmospheric Sciences
National Central University (http://www.ncu.edu.tw/)
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