Dear John,
> I think this concept assumes the netCDF file will never be used in any other context (e.g, as a timestep in a shorter or longer forecast sequence), and the data set will no change (because if it does, every file must be reviewed for min/max values that need updating). Is that a correct understanding?
I was thinking that that the min/max for the whole dataset cannot be
the actual min/max, unless this is somehow known in advance (e.g. for
a static dataset). I was suggesting that each file in the dataset
should contain a "reasonable" min/max, given the context of the
dataset (e.g. a numerical model of the Arctic ocean temperature would
have a different dataset_min and dataset_max from a set of
observations in the tropics).
Actually, come to think of it, if the actual min/max for a variable is
stored in each file, it's a relatively cheap operation to calculate
the overall min/max for a set of files (depending on the number of
files in the dataset, obviously). So maybe the most important
attribute pair is the actual min/max of each variable in a particular
file (which I suggested could be called data_min and data_max, to
distinguish from valid_min and valid_max).
Regards, Jon
On 1/8/07, John Graybeal <graybeal at mbari.org> wrote:
> I think this concept assumes the netCDF file will never be used in any other context (e.g, as a timestep in a shorter or longer forecast sequence), and the data set will no change (because if it does, every file must be reviewed for min/max values that need updating). Is that a correct understanding?
>
> I wonder if we want to promote characterizing whole datasets inside every constituent of the set. Does CF do this in other contexts?
>
> John
>
> At 10:31 AM +0000 1/8/07, Jon Blower wrote:
> >...
> >2) If the netCDF file is part of a larger dataset (e.g. it represents
> >one timestep in a forecast sequence) it would be useful to store a
> >"reasonable" (or actual, if possible) min and max for the *whole
> >dataset* (taking into account the measurement method used,
> >geographical region etc).
>
> --
> ----------
> John Graybeal <mailto:graybeal at mbari.org> -- 831-775-1956
> Monterey Bay Aquarium Research Institute
> Marine Metadata Initiative: http://marinemetadata.org || Shore Side Data System: http://www.mbari.org/ssds
>
--
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Technical Director Tel: +44 118 378 8741 (ESSC)
Reading e-Science Centre Fax: +44 118 378 6413
ESSC Email: jdb at mail.nerc-essc.ac.uk
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Received on Mon Jan 08 2007 - 11:35:12 GMT
