I'm not entirely sure I follow the desired result. It seems that you want a "straight" line rather than the great circle points calculated by gclatlon. <div>If so could you not just create your own array of points using fspan for the lats and lons and pass them to the interpolation function. </div><div><br></div><div>Example plots of what you are getting versus what you desire might help. <br><div><br>On Sunday, May 29, 2016, Adam Herrington <<a href="mailto:adam.herrington@stonybrook.edu">adam.herrington@stonybrook.edu</a>> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">the following example cleared up some of my confusion: <a href="https://www.ncl.ucar.edu/Applications/Scripts/polyg_14.ncl" target="_blank">https://www.ncl.ucar.edu/Applications/Scripts/polyg_14.ncl</a><div><br></div><div>The two procedures are not identical. My only question now is, how to compute a transect that mimicks:</div><div><br></div><div><pre style="color:rgb(0,0,0);word-wrap:break-word;white-space:pre-wrap"> res@mpGreatCircleLinesOn = True
;---Create the map, but it won't be drawn yet.
plot1 = gsn_csm_map_ce(wks,res)
;---Resources for the polyline
pres = True ; polyline mods desired
pres@gsLineThicknessF = 2.0 ; line thickness
pres@gsLineColor = "blue" ; color of lines
;---Attach the polyline
dum1 = gsn_add_polyline(wks,plot1, (/lon1, lon2/) , (/lat1, lat2/) ,pres)
</pre></div><div><br></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Sun, May 29, 2016 at 1:07 AM, Adam Herrington <span dir="ltr"><<a href="javascript:_e(%7B%7D,'cvml','adam.herrington@stonybrook.edu');" target="_blank">adam.herrington@stonybrook.edu</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div>In regards to the only transect example (<a href="https://www.ncl.ucar.edu/Applications/transect.shtml" target="_blank">https://www.ncl.ucar.edu/Applications/transect.shtml</a>), is there any reason we should doubht that the transect computed from gc_latlon:</div><div><br></div><div><pre style="color:rgb(0,0,0);word-wrap:break-word;white-space:pre-wrap"> dist = gc_latlon(leftlat,leftlon,rightlat,rightlon,npts,2)
</pre></div><div>is accurately depicted by:</div><div><pre style="color:rgb(0,0,0);word-wrap:break-word;white-space:pre-wrap"> map = gsn_csm_map_ce(wks,mres) ; create map</pre></div><div><pre style="color:rgb(0,0,0);word-wrap:break-word;white-space:pre-wrap"><pre style="word-wrap:break-word;white-space:pre-wrap"> gsn_polyline(wks,map,(/leftlon,rightlon/),(/leftlat,rightlat/),pres)</pre></pre></div>? I am not sure that gc_latlon and gsn_polyline (as portrayed on gsn_csm_map_ce, e.g. a global gridded dataset) use the same procedure to compute a transect, given identical input (rightlon, leftlon, etc...)<div><br></div><div>If the two procedures are not consistent, does anyone know a way to </div><div>(a) actually plot the transect from gc_latlon on a map (directly plot variable 'trans', in the example?), or <br></div><div>(b) compute a transect the same way that gsn_polyline and gsn_csm_map_ce do.</div><div><br></div><div>Thanks in advance!</div><span><font color="#888888"><div><br></div><div>Adam</div></font></span></div>
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