Re: Bug - issue with res@mpMaxLonF and res@mpMinLonF at branch cut (180 degrees E)

Don,

To fix this problem, you want to additionally set mpCenterLonF
to some value between mpMinLonF and mpMaxLonF, like 224. Then,
it won't matter whether mpMinLonF is 179.1 or 180.1.

I'm not sure why the plots are so different when mpMinLonF is set to
179 versus 180. I'll check to make sure this isn't a bug.

--Mary

On Sun, 13 Apr 2008, Don Stark wrote:

> 1. % ncl -V5.0.0
> 2. This example follows from the raster pop example. See code attached at the
> end of this email. The issue is that the declarations for res_at_mpMaxLonF and
> res_at_mpMinLonF fail at the branch cut. It plots correctly when res_at_mpMinLonF >
> 180, but fails when res_at_mpMinLonF =< 180. This is independent of whether the
> units are degrees east (-180:180) or just degrees (0:360). In the current
> example the longitude units are degrees.
>
> 3. file too large, should be independent of specific file.
> 4. See two images below. The good has res_at_mpMinLonF = 180.1. the bad has
> res_at_mpMinLonF = 179.1
> 5. No error message
> 6. mac OSX 10.4 on a G4
>
> --
> ---------------------------------------------------------------
> Don Stark, PhD stark_at_ucar.edu
> NCAR, Boulder CO
> 303.497.2472
> ---------------------------------------------------------------
>
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"
> ;*****************************************************
> begin
> f1 = addfile("out_gx1v4_to_NEP4_Wcurtain_bilin_da_080407.nc","r")
>
> ; convert pop grid from radioans to degrees
> scale = 180.0/3.1415927
>
> src_lat2d = f1->src_grid_center_lat*scale ; extract 2D grid
> src_lon2d = f1->src_grid_center_lon*scale
>
> dims = dimsizes(src_lon2d) ; get dimension sizes
> dims(1) = dims(1) + 1 ; increase longitude by 1
> nlat = dims(0)
> nlon = dims(1)
>
> lon2d = new(dims,typeof(src_lon2d)) ; create new arrays
> lat2d = new(dims,typeof(src_lat2d))
>
> lat2d(:,1:nlon-1) = src_lat2d ; fill in arrays
> lon2d(:,1:nlon-1) = src_lon2d
> lon2d(:,0) = src_lon2d(:,nlon-2)
> lat2d(:,0) = src_lat2d(:,nlon-2)
>
> lat2d_at_units = "degreeN"
> lon2d_at_units = "degrees"
>
> ; Source variables
> src_array = f1->src_array(1:nlat-1,:) ; POP array
> f = src_array
>
> f_at_lat2d = lat2d
> f_at_lon2d = lon2d
>
> ;=================================================;
> ; Create plot
> ;=================================================;
> wks = gsn_open_wks("ps","popgrid") ; open a ps file
> gsn_define_colormap(wks,"BlAqGrYeOrRe") ; choose colormap
> res = True ; plot mods desired
> res_at_cnFillOn = True ; turn on color fill
> res_at_cnFillMode = "RasterFill" ; turn on raster mode
> res_at_cnLinesOn = False ; turn off contour lines
> res_at_gsnSpreadColors = True ; use full colormap
> res_at_gsnSpreadColorStart = 10 ; start at color 10
> res_at_gsnSpreadColorEnd = 96 ; end at color 96
>
> ; zoom in on map
> res_at_mpMaxLatF = max( lat2d(250:350,160:265) )
> res_at_mpMinLatF = min( lat2d(250:350,160:265) )
> res_at_mpMaxLonF = 267.9
> res_at_mpMinLonF = 180.1
>
> plot = gsn_csm_contour_map_ce(wks,f,res)
> end
_______________________________________________
ncl-talk mailing list
ncl-talk_at_ucar.edu
http://mailman.ucar.edu/mailman/listinfo/ncl-talk
Received on Tue Apr 15 2008 - 08:08:18 MDT