Re: Plotting EASE grids

Hi Gina,

Dennis is out this week, and I'm not familiar with this grid, but if you can provide your data set, please email me separately and I'll let you know where you can upload it.
I'm also not sure what the EastLatLon.nc file is, and would need this.

Did you try plotting the original 1024 x 1024 grid with NCL?

--Mary

On Jul 28, 2010, at 11:33 AM, Gina Henderson wrote:

> Hi there,
>
> I regridded some ims data from 1024x1024 to EASE grid format, 721x721. The NSIDC tool I used for the transform output the data in hexadecimal form so I used ncl's stringtointeger tool to read it. I then used Dennis Shea's EaseLatLon.nc coordinate file together with the ncl example ease_1.ncl to try and plot the data, however my georeferencing seems to be off (please see attached pdf).
>
> I am trying to figure out if it is only a plotting/georeferencing problem or does the error go deeper to the way I performed the grid transform.
>
> Attached are the ncl script that reads and plots the data together with the ouptput. Any suggestions you might have would be great.
> Thanks, Gina.
>
>
> -------------------------------------------------------------
> begin
>
> nlat=721
> nlon=721
>
> ims = fbindirread ("ims2008349.ease1",0,(/nlat,nlon/), "byte")
> printVarSummary(ims)
> ;print(ims)
>
> ims_int = stringtointeger(ims)
> printVarSummary(ims_int)
> ;print(ims_int)
>
> a = addfile("EaseLatLon.nc","r")
>
> lat = a->latitude
> lon = a->longitude
>
> printVarSummary(lat)
> printVarSummary(lon)
>
> ;*******************************************
> ; Create plots
> ;*******************************************
>
> wks = gsn_open_wks("ps","ims_ease1")
> gsn_define_colormap(wks,"amwg") ; Change color map
>
> res = True ; Plot modes desired.
> res@gsnMaximize = True ; Maximize plot
> res@gsnSpreadColors = True ; use full range of colormap
> res@cnFillOn = True ; color plot desired
> res@cnLinesOn = False ; turn off contour lines
> res@cnFillMode = "RasterFill" ; turn raster on
> ; res@pmLabelBarWidthF = 0.9 ; make wider
> ; res@pmLabelBarHeightF = 0.1 ; default is taller
> ; res@lbLabelFontHeightF = .018 ; default is HUGE
>
> res@cnLevelSelectionMode= "ExplicitLevels" ; set explicit contour levels
> res@cnLevels = (/48,49,50,51,52/) ;\
> ; ,5,253,254,255/)
>
> ;************************************************
> ;No georeferencing: simple contour. Draws faster
> ;************************************************
> res@tiMainString = "Ims 1024x1024 to EASE grid 721x721"
> plot = gsn_csm_contour(wks,ims_int,res) ; contour, no map
>
> ;*******************************************
> ; georeferencing: plot on polar projection
> ;*******************************************
> ; georeference
> ims_int@lat2d = lat
> ims_int@lon2d = lon
>
> res@trGridType = "TriangularMesh" ; allow missing coordinates
>
> res@gsnPolar = "NH" ; specify the hemisphere
> res@mpMinLatF = 35
> res@tiMainString = "gsn_csm_contour_map_polar"
>
> plot = gsn_csm_contour_map_polar(wks,ims_int,res)
>
> end
>
>
> <ims_ease1.pdf>_______________________________________________
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Received on Thu Jul 29 16:12:26 2010