I am not an R expert so this may be a problem. Any way, try running the command ncdump -k /data1/wlduan/d4PDF/sample/4.apdaba.pag1j0.05216.nc It should tell you what kind of file it is. It should say something like netcdf-4 or netcdf enhanced. =Dennis Heimbigner Unidata Ticket Details =================== Ticket ID: VNX-965855 Department: Support netCDF Priority: Normal Status: Open =================== NOTE: All email exchanges with Unidata User Support are recorded in the Unidata inquiry tracking system and then made publicly available through the web. If you do not want to have your interactions made available in this way, you must let us know in each email you send to us.