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","contour6b") ; Open "contour6b.png" png file. res = True ; Plot options desired. res@mpLimitMode = "Corners" ; Choose range of map. res@mpLeftCornerLatF = lat2d@corners(0) res@mpLeftCornerLonF = lon2d@corners(0) res@mpRightCornerLatF = lat2d@corners(2) res@mpRightCornerLonF = lon2d@corners(2) plot = gsn_csm_contour_map(wks,vpt,res) ; Call gsn_csm function for ; drawings contours over a map. end