Re: time unit in CF-netCDF

[Benno Blumenthal <benno@xxxxxxxxxxxxxxxx>]

To be CF compliant, you should write the units in days and use 
time-bounds to set the edges of the (irregular) intervals.  the 
attribute unit must be in udunits -- P4D is not or P 4 day are not 
acceptable.


Benno


Wenli Yang wrote:



> Hi,
>
> How to express the unit of an irregular period of time in the time 
> coordinate variable in CF-netCDF?    For example, for two 4-day 
> periods: a) between 2007-01-01 and 2007-01-04; and b) between 
> 2007-01-05 to 2007-01-08, which of the followings are correct?
>     1. time(time)=1,2       unit = "P 4 day since 2007-01-01"
>     2. time(time)=1,2       unit = "P4D since 2007-01-01"
>
> There are names for regular time periods, such as week and fortnight, 
> in udunits.dat.  For irregular time period, such as 3 days 1 hours and 
> 5 minutes, I am not sure if we should use  ISO 8601 expression, 
> "P1M3DT1H5M" or something like "P 1 month 3 day 1 hour 5 minute" as unit.
>
> Thanks.
>
> Wenli
>
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