[ncl-talk] Hovmoller Plot with 2d lat/lon (Y coordinates out of data range)

[Mary Haley]

Dave,

The gsn_csm_hov script is meant to only be for rectilinear grids, and you
are trying to use it on a curvilinear grid (i.e., one represented by 2D
lat/lon grids). The documentation is not clear about this unfortunately.

My suggestion is to just use gsn_csm_contour, and pass in the time and
longitude arrays via the sfYArray and sfXArray resources:

new_time = conform(new_lon(:,0,:),time,0)
res at sfYArray = new_time
res at sfXArray = new_lon

--Mary


On Thu, Oct 9, 2014 at 8:28 PM, David Adams <dave.k.adams at gmail.com> wrote:

> HI NCLers,
> I am trying to make a hovmoller plot but it does appear that my
> coordinates are correct.
>
> warning:ContourPlotInitialize: Y coordinates out of data range: defaulting
> warning:ContourPlotInitialize: Zero Y coordinate span:
> defaulting:[errno=1104]
>
> and then a blank plot.  The code is from the NCL website with slight
> modification
>
>
> --------------------------------------------------------------------------------
> begin
> ;=============================================
> ; data processing
> ;===========================================
>  fili  = "test.nc"                 ; filename
>   f     = addfile (fili , "r")             ; add file
>  new_temp   = f->new_temp                                ; get chi
>  new_lat  = f->new_lat
>  new_lon  = f->new_lon
> ;==============================================
> ; creat plot: Reverse time axis; contour labels horizontal
> ; Dash negative contours; double width of Zero
> ;==============================================
>  wks  = gsn_open_wks ("pdf", "hov")
>  res                     = True                ; plot mods desired
>  res at gsnContourZeroLineThicknessF = 2.         ; doubles thickness of
> zero contour
>  res at gsnContourNegLineDashPattern = 1          ; sets negative contours
> to dash pattern 1
>  res at trYReverse          = True                ; reverse y axis
>  res at tiMainString        = "Reverse Time"      ; title
>  res at cnLineLabelAngleF   = 0.0                 ; [cn] label horizontal
>
> ;new_temp at lat2d = new_lat(0,:,:)
> ;new_temp at lon2d = new_lon(0,:,:)
>
>  plot  = gsn_csm_hov(wks, new_temp(:,0,:), res )           ; default
> hovmueller
> end
>
> --------------------------------------------------------------------------------------------
> Here is an ncdump -h on the data file
>
> netcdf test {
> dimensions:
>     yc = 221 ;
>     xc = 141 ;
>     time = UNLIMITED ; // (130 currently)
> variables:
>     float new_temp(time, yc, xc) ;
>         new_temp:time = 1372896900 ;
>         new_temp:units = "K" ;
>         new_temp:coordinates = "lon lat" ;
>         new_temp:type = "GVAR" ;
>         new_temp:long_name = "Temperature" ;
>     float new_lat(time, yc, xc) ;
>         new_lat:units = "degrees_north" ;
>         new_lat:long_name = "lat" ;
>     float new_lon(time, yc, xc) ;
>         new_lon:units = "degrees_east" ;
>         new_lon:long_name = "lon" ;
>     int time(time) ;
>         time:units = "seconds since 2013-185 00:15" ;
>
>
> any obvious errors?
>
> thanks in advance,
> Dave
>
>
>
>
>
>
>
>
>
>
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