We will be transitioning the data files from netCDF3 to netCDF4-classic format. As a result, the files will be compressed instead of being packed with a scale and offset. As with any netCDF4 file, the NetCDF library will perform the uncompression. We expect the files to be read faster, depending on the application you are using. Values may differe slightly because of precision issues. Please let us know if you run into any problems after first reading our netCDF4 doc . We are also changing the time acces to use 1800 as a reference date for udunits. This should prove easier for users.