Two conventions for storing a date/time into a netCDF variable are:

1. ISO-compliant: as a string using ISO 8601 encoding, such as "2010-10-25T12:00:00Z".
2. CF-compliant: as a numeric value and unit that includes the reference data and time, such as 2116800 "seconds since 2010-10-01 00:00:00".

Unidata's udunits package provides a convenient way to implement the second strategy, and the "-t" option to ncdump displays resulting times in human readable form, close to ISO-8601, e.g. "2010-10-25 12".

• If your data uses real, physical time, encode it as an interval from a reference time, and add a udunits-compatible time unit. Readers can use the udunits package to manipulate or format the date values.

2010 Unidata NetCDF Workshop > Best Practices