Re: EOF1 Correlated to Global SST's

Hi Melissa,

the script seems to be fine. It's very hard to read though. The only
thing I can see is that maybe you want to use precipitation and sst
anomalies instead of the full data for your EOFs and the correlations.

Also the map and the land areas don't match up. Why are you doing this:
y&lat@units <mailto:y&lat@units> = "degrees_north"
y&lon@units <mailto:y&lon@units> = "degrees_east"

before computing the correlations? And I don't think this is what you
want either

ccr!0 = "lat" ; name dimensions
   ccr!1 = "lon"

ccr has dimensions (neof,lat,lon). (This may be why your map comes out
wrong)

I assume the SST data you are reading has lat lon values attached to it,
so you could try to do

copy_VarCoords(sst1(0,:,:),ccr1)

after you define ccr1. This should give you the correct coordinates for
plotting.

Hope this helps,
Maria

On 11/14/2013 06:45 AM, Melissa Lazenby wrote:
>
> Hi All
>
> I am trying to correlate the first principal component or EOF 1 with
> global SST's
>
> I have created a script in which to do this but am not quite getting
> it right as it is supposed to look like this
>
> corr Dec-Feb monthly PC1 of CMAP precipitation / s.d. \with Dec-Feb
> monthly HadISST1 SST 1979:2008 p<10%
>
> But I am getting nothing of the sort (attached) and I am trying to
> figure out where my problem lies.
>
> My code is attached below and if anyone can see something wrong with
> this please any advice is very welcome.
>
> Many thanks for your help in this matter.
>
> Kind Regards
>
> Melissa
>
> ; ==============================================================
> ; eof_1.ncl
> ;
> ; Concepts illustrated:
> ; - Calculating EOFs
> ; - Using coordinate subscripting to read a specified geographical
> region
> ; - Rearranging longitude data to span -180 to 180
> ; - Calculating symmetric contour intervals
> ; - Drawing filled bars above and below a given reference line
> ; - Drawing subtitles at the top of a plot
> ;
> ; ==============================================================
> ; Calculate EOFs of the Sea Level Pressure over the North Atlantic.
> ; ==============================================================
> ; The slp.mon.mean file can be downloaded from:
> ;
> http://www.esrl.noaa.gov/psd/data/gridded/data.ncep.reanalysis.surface.html
> ; ==============================================================
>
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl"
>
> begin
> ; ==============================================================
> ; User defined parameters that specify region of globe and
> ; ==============================================================
> latS = -40.
> latN = 0.
> lonL = 10.
> lonR = 60.
>
> yrStrt = 1979
> yrLast = 2009
>
> season = "DJF" ; choose Dec-Jan-Feb seasonal mean
>
> neof = 1 ; number of EOFs
> optEOF = True
> optEOF@jopt <mailto:optEOF@jopt> = 0 ; This is the default; most
> commonly used; no need to specify.
> ;;optEOF@jopt = 1 ; **only** if the correlation EOF is desired
>
> optETS = False
>
> ; ==============================================================
> ; Open the file: Read only the user specified period
> ; ==============================================================
> f = addfile ("/mnt/nfs2/geog/ml382/melphd/global/cmap_eof1.nc",
> "r")
>
> lat = f->lat
> TIME = f->time
> YYYY = cd_calendar(TIME,-1)/100 ; entire file
> iYYYY = ind(YYYY.ge.yrStrt .and. YYYY.le.yrLast)
>
> PR = f->precip(iYYYY,:,:)
> printVarSummary(PR)
> ; variable overview
>
> s = addfile
> ("/mnt/nfs2/geog/ml382/melphd/global/oisst_global1.nc", "r")
>
> sst = s->sst
> ;lat = s->lat
> ;lon = s->lon
> ;TIME = s->time
> printVarSummary(sst) ; variable overview
> sst1 =sst(:,:,:)
>
> ; ==============================================================
> ; compute desired global seasonal mean: month_to_season (contributed.ncl)
> ; ==============================================================
> ;PR = month_to_season (precip, season)
> nyrs = dimsizes(PR&time)
> ;printVarSummary(PR)
>
> ; =================================================================
> ; normalize data at each gridpoint by local standard deviation at each
> grid pt
> ; =================================================================
> PR = dim_standardize_n(PR,1,0)
>
> ; =================================================================
> ; Reorder (lat,lon,time) the *weighted* input data
> ; Access the area of interest via coordinate subscripting
> ; =================================================================
> x = PR({lat|latS:latN},{lon|lonL:lonR},time|:)
>
> 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)
>
> ;Correlations of EOF1 and global sst anomalies
>
> y = sst1(lat|:,lon|:,time|:)
>
> y&lat@units <mailto:y&lat@units> = "degrees_north"
> y&lon@units <mailto:y&lon@units> = "degrees_east"
>
> ccr = escorc(eof_ts, y)
>
> printVarSummary(ccr)
> print(ccr)
>
> ccr!0 = "lat" ; name dimensions
> ccr!1 = "lon"
> ;ccr&lat@units = "degrees_north" ; assign coordinate values and
> ;ccr&lon@units = "degrees_east" ; units attributes
>
>
> ccr1=ccr(0,:,:)
> print(ccr1)
>
> yyyymm = cd_calendar(eof_ts&time,-2)/100
> ;;yrfrac = yyyymm_to_yyyyfrac(yyyymm, 0.0); not used here
>
> ;============================================================
> ; PLOT
> ;============================================================
>
> ;*******************************************
> ; global plot
> ;*******************************************
> wks = gsn_open_wks("X11","globalmap")
> gsn_define_colormap(wks,"gui_default") ; choose colormap
>
> rescn = True
> rescn@cnFillOn <mailto:rescn@cnFillOn> = True
> ;rescn@gsnDraw = False ; don't draw
> ;rescn@gsnFrame = False ; don't advance frame
>
> rescn@cnLevelSelectionMode <mailto:rescn@cnLevelSelectionMode> =
> "ManualLevels" ; set manual contour levels
> rescn@cnMinLevelValF <mailto:rescn@cnMinLevelValF> =
> -0.6 ; set min contour level
> rescn@cnMaxLevelValF <mailto:rescn@cnMaxLevelValF> =
> 0.6 ; set max contour level
> rescn@cnLevelSpacingF <mailto:rescn@cnLevelSpacingF> =
> 0.2 ; set contour spacing
>
> rescn@lbOrientation <mailto:rescn@lbOrientation> = "Vertical"
> ; vertical label bar
>
> ;---This resource defaults to True in NCL V6.1.0
> rescn@lbLabelAutoStride <mailto:rescn@lbLabelAutoStride> =
> True ; optimal label stride
>
> rescn@gsnSpreadColors <mailto:rescn@gsnSpreadColors> =
> True ; use full range of colors
>
> rescn@mpCenterLonF <mailto:rescn@mpCenterLonF> = 180. ;
> center plot at 180
>
>
> rescn@gsnAddCyclic <mailto:rescn@gsnAddCyclic> = True
>
>
> plot = gsn_csm_contour_map(wks,ccr1,rescn)
>
> end
>
>
>
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-- 
Maria Gehne
Postdoctoral Fellow
NCAR/CGD/CAS
P.O. Box 3000
Boulder, CO 80307

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Received on Thu Nov 14 08:36:59 2013