[ncl-talk] Adding a marker on a contouring map

[G.Monte at isac.cnr.it]

Dear all,
I would like to add a marker for a given latitude-longitude
(45.43°N,12.12°E) on a contouring map in NCL 6.4.0. For the plot, I used
gsn_csm_contour_map function and I need only a single marker to add in. I
tried the following commands:

polyres                   = True
polyres at gsMarkerIndex     = 16
polyres at gsMarkerSizeF     = 5.
plot =  gsn_csm_contour_map(wks,Z_region,res)
dum  =  gsn_add_polymarker(wks,plot,12.12,45.43,polyres)
draw(plot)

and no error messages appeared, but marker was not added on the map anyway.
I do not understand the reason; maybe, I think that gsn_add_polymarker
function would be suited only for several markers. Are there existing
other functions to add a single marker on a NCL contouring map?

Thanks,
Giulio Monte