[Go-essp-tech] Corrected THREDDS group wiki page link

[Karl Taylor]

Hi all,
I've just looked up the output requirements, and found that we were very 
explicit about the basetime not changing from one file to another within 
an experiment and also in going from the historical run to a future 
scenario run.  Here are the requirements taken from the document ( 
CMIP5_output_metadata_requirements.pdf 
<http://cmip-pcmdi.llnl.gov/cmip5/docs/CMIP5_output_metadata_requirements.pdf>) 
linked at http://cmip-pcmdi.llnl.gov/cmip5/output_req.html#metadata .  
There it says:

? For all time coordinates the units must be "days since <basetime>", 
where <basetime> must be specified by the user, typically in the form 
year-month-day (e.g., "days since 1800-01-01").Follow these rules:

? The same 'base time' should apply to all time samples in a single 
simulation (i.e., when creating a series of files containing model 
output for a single run, don't change the units or 'base time' from one 
file to the next; in the above example 1800-01-01 is the 'base time').

? For simulations meant to represent a particular historical period, set 
the 'base time' to the time at the beginning of the simulation.A 
historical run initialized with forcing for year 1850 would, for 
example, have units of "days since 1850-01-01".The 'base time' used in 
the control run is irrelevant as is the time in the control run when the 
historical run was initialized.

? For the future scenario runs, retain the same 'base time' as used in 
the historical run from which it was initiated.

? For simulations not tied to a particular date, the 'base time' is 
arbitrary, but it should correspond to the beginning of the run.Thus, in 
these simulations, 'base time' is whatever time one decides to assign to 
the beginning of the run.

? All values of the time coordinate should be positive, which will be 
ensured by following the above rules.



I guess the QC or publisher should object if these rules are not followed.

Best regards,
Karl
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