ACCESS NetCDF data file notes

  • ACCESS NetCDF files aim to be broadly compliant with CF 1.4 conventions (
  • All ACCESS NetCDF data is in netCDF-4/HDF5 data model format, compatible with (compatible with the Unidata NetCDF library version 4.x.y+).
  • NetCDF data has been compressed, although this should be transparent to users/applications. Future ACCESS APS releases may include rounding/packing strategies to help optimise compression further. Currently no packing of NetCDF data is performed.
  • Please treat the accum_value metadata values as inaccurate. It is known that this parameter is set incorrectly for all accumulated fields (e.g. accumulated precipitation) and is also incorrect for all ACCESS-G time-averaged values. All accumulated quantities are accumulated from the start of the ACCESS 4D-VAR assimilation window which is set at three hours before the ACCESS model nominal base-date/time. The time period used to calculate time-averaged and max/min fields is always relative to the last available output time-step. For example this period would be 3-hours for ACCESS-G and an hour for other models.
  • Longitudes in the NetCDF files lie in the range [0.0 degrees, 360.0 degrees]. The NetCDF files somewhat misleadingly describe the valid range attribute for this dimension as -180 to +360.