Re: [ferret_users] ferret and aggregation with different time references (T0)

[Brockmann Patrick <Patrick.Brockmann@xxxxxx>]

> I have discovered that when an aggregation has been made over time
> with files that contains different time references then the result 
> time axis
> is not correct (not monotically increasing).
>
> Precisely, I have files with
>               time:units = "days since 1850-01-01 00:00:00" ;
> others with
>               time:units = "days since 1870-01-01 00:00:00" ;
> or
>               time:units = "days since 1880-01-01 00:00:00" ;
> or
>               time:units = "days since 1970-01-01 00:00:00" ;
>
> Is this problem can be solved by ferret or when the aggregation is 
> built ?
> But I have found any information on this on 
> http://www.unidata.ucar.edu/projects/THREDDS/tech/tds4.2/reference/index.html 
>
> so I post this topic on the client side since ferret could also manage 
> this issue.
>
> Let me know, if I have missed something.

Indeed there is element to add and it should work with thredds clients 
and ferret.

> From the aggregation documentation :
http://www.unidata.ucar.edu/software/netcdf/ncml/v2.2/Aggregation.html
when the units of the aggregation coordinate change on the existing coordinate variables, you must add timeUnitsChange="true" on the aggregation element:

Patrick

--
LSCE/IPSL, Laboratoire CEA-CNRS-UVSQ
Data Analysis and Visualization Engineer
ICMC - IPSL Climate Modelling Centre
--