begin f = addfile ("ruc2.bgrb.20020418.i12.f00.grb","r") vpt = f->VPTMP_252_HYBL(0,:,:) lat2d = f->gridlat_252 ; 2D latitude grid lon2d = f->gridlon_252 ; 2D longitude grid vpt@lat2d = lat2d ; Must attach lat2d and vpt@lon2d = lon2d ; lon2d as special attributes. wks = gsn_open_wks("png","contour6a") ; Open "contour6a.png" png file. res = True ; No plot options desired. plot = gsn_csm_contour_map(wks,vpt,res) ; Call gsn_csm function for ; drawings contours over a map. end