NCL 怎样标出位置点？

权威

before you call wrf_map_overlays. Then, call the appropriate gsn_add_polyxxxx routine to attach the desired primitives, and finally call draw(plot) and frame(wks) to draw the plot with the attached primitives and advance the frame.理解draw(plot)在gsn_polymarker(wks,plot,116,40,res)
gsn_add_polymarker(wks,plot,116,40,res)之前， frame(wks)在gsn_polymarker(wks,plot,116,40,res)
gsn_add_polymarker(wks,plot,116,40,res)之后，否则看不到效果