[ncl-talk] Radar data plotting, no MAP_PROJ attribute

[Mary Haley]

Hi Ryan,

You can't use wrf_xxxx functions to plot anything but WRF-ARW data.  These
functions assume that you are using WRF files with names like
"wrfout_d01_2008-09-28_00:00:00" which have a bunch of global attributes in
them that define the native map projection of the WRF data. This is why you
were getting an error about MAP_PROJ being undefined.  This is one of the
required global attributes.

If you are trying to plot the data over a map, then you will need to
examine your file and your data variable (rd_plane) to determine if it is
also on some native map projection, or whether you need to provide lat/lon
coordinates for plotting.  I then suggest using the gsn_csm_contour or
gsn_csm_contour_map functions to generate just contours, or contours over a
map.

Please see this page for some examples on how to plot data over a map using
NCL:

http://www.ncl.ucar.edu/Applications/plot_data_on_map.shtml

You might also want to look at this page:

http://www.ncl.ucar.edu/Applications/radar.shtml


--Mary


On Fri, Jul 8, 2016 at 4:35 PM, Ryan Connelly <rconne01 at gmail.com> wrote:

> Hi,
>
> I have Level II radar data in netcdf format (using radx and the steps
> outlined here:
> https://publish.illinois.edu/snesbitt/resources/radar-data-processing-with-radx/
> ).
>
> I want to overlay it on a base map, in the same way I would with WRF
> data.  Here's a highly condensed version of what I have:
>
> rf    = addfile(diri+fili,"r")
>        rd    = rf->REF(:,:,:,:)          ; float REF(time, z0, y0, x0) ;
> RHO, ZDR
>
>        rd_plane = rd(0,0,:,:)
>
>        contour =  gsn_csm_contour(wks,rd_plane,radres)
>        plot = wrf_map_overlays(rf,wks,(/contour/),radres,mpres)
>
> I was just assuming the netcdf had location data packaged into it, but I
> get the error:
>
> (0) wrf_map: Error: no MAP_PROJ attribute in input file
> fatal:overlay: missing value as input, can't continue
>
> I tried adding in a wrf file I had laying around and using it for map
> plotting, and while that got be a basemap, by radar data was obviously not
> matched geographically (it showed the KOKX RDA over New York City!).
>
> Thanks,
> Ryan
>
> --
> Ryan Connelly
> M.S. Student in Atmospheric Sciences, Stony Brook University
> B.S. in Meteorology with Minors in Mathematics and GIS, Valparaiso
> University
> rconne01 at gmail.com
> ryan.connelly at stonybrook.edu
>
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