Hi Michal, > I have been using the command "nc2text" to extract data from the "Link to > files" data set in the link below that extracts the netCDF file " > hgt.mon.mean.nc". This is or has always been a netCDF file and has worked > for me over the past couple of years, yet this month for the first time the > program is telling me "Not a netCDF file" and does not work. The file size > of the file "hgt.mon.mean.nc" looks to be about 1/2 of what it should be > compared to last month so I susspect the upload to the ftp server has > failed. But I do not know if NOAA changed the format or if its corrupt just > this month. If the format has changed then has there been an update to > "nc2text"?. I have no idea currently. > > http://www.esrl.noaa.gov/psd/cgi-bin/db_search/DBSearch.pl?Dataset=CDC+Derived+NCEP+Reanalysis+Products+Pressure+Level&Variable=Geopotential+height&Statistic=Mean&group=0&submit=Search NOAA changed to use netCDF-4 classic model format instead of netCDF classic format. The data is still in a netCDF format that can be read by any previous netCDF program, as long as the program is relinked to the netCDF-4 library. You are probably using nc2text linked with the older netCDF-3 library that did not support lossless compression of data. This is a feature of netCDF-4 that many organizations are making use of, because it results in significantly smaller data files that can be accessed more quickly across a network. More information about the netCDF-4 classic model format is available from the links below: http://www.unidata.ucar.edu/netcdf/docs/faq.html#formats-and-versions http://www.unidata.ucar.edu/netcdf/workshops/2012/performance/ http://www.unidata.ucar.edu/presentations/Rew/netcdf-intro-2014.pdf If you compiled nc2text from source, you shouldn't have to change anything in the program. Instead, you need to download a more recent version of netCDF-4, build and install it, then compile and link nc2text to use the newly installed netCDF C library. You can get the new version and instructions for building it from here: http://www.unidata.ucar.edu/netcdf/docs/ --Russ Russ Rew UCAR Unidata Program address@hidden http://www.unidata.ucar.edu Ticket Details =================== Ticket ID: RJB-156641 Department: Support netCDF Priority: Normal Status: Closed