<div dir="ltr"><div>By default, NCL uses a proprietary [fast] method for this type of graphic rendering. Obviously, it was not great for this graphic.</div><div><br></div><div>It is best to use (say) <b>obj_anl_ic </b>and then use a USA shapefile to eliminate 'noises' outside the  USA. See:<br></div><div><br></div><div><a href="http://www.ncl.ucar.edu/Applications/shapefiles.shtml"><b>http://www.ncl.ucar.edu/Applications/shapefiles.shtml</b></a></div><div>shapefiles_25 and shapefiles_26.</div><div><br></div><div>The raster style was used to illustrate the underlying grid onto which the randomly spaced data were interpolated.</div><div>You can comment tor delet he RasterFil resource.</div><div><br></div><div>Good luck<br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Mon, Nov 25, 2019 at 10:29 AM Wensong Weng via ncl-talk <<a href="mailto:ncl-talk@ucar.edu">ncl-talk@ucar.edu</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">




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Dear NCL Group,</p>
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I am using the gsn_csm_contour_map function to make a contour plot for the precipitation, see the attached. However, there are lots of un-wanted ‘noises’ outside of CONUS (no data).  The data is a one dimension array with unstructured grids. How can I get rid
 of those ‘noises’ and only draw the contour map over the CONUS.</p>
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Your help is greatly appreciated,</p>
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Wensong Weng</p>
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York Univ.</p>
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