begin a = addfile("pop.nc","r") ; Read in POP data. u = a->urot(::4,::4) ; If you don't thin the data v = a->vrot(::4,::4) ; the streamlines are too dense. u@lat2d = a->lat2d(::4,::4) ; Attach 2D lat/lon arrays u@lon2d = a->lon2d(::4,::4) ; to both urot and vrot. v@lat2d = a->lat2d(::4,::4) ; These have to be the same v@lon2d = a->lon2d(::4,::4) ; size as u and v. wks = gsn_open_wks("png", "stream2a") ; Open "stream2a.png" png file. res = False ; No plot options set. plot = gsn_csm_streamline_map(wks,u,v,res) ; Call gsn_csm routine for ; drawing streamlines over map. end