Hi Jon -
I think the term 'resolution' might be more correct in this case than
'precision' - These are the definitions we use, although I can't quite
find the source:
* Resolution is the fineness to which an instrument can be read.
* Precision is the fineness to which an instrument can be read
repeatably and reliably.
I'm also using the attribute 'C_format' - don't recall exactly which
convention
uses that, but it's a good way to indicate 'vagueness' - but I'm not
sure how
or if it could be used to indicate that the dates are only good to whole
days.
Cheers - Nan
Hi Mike,
This is useful, thanks. However, I'm not sure that this concept of
"uncertainty" is exactly the same as my notion of "nominal precision"
(maybe I've chosen a bad name). For example, I know for sure that an
OSTIA daily analysis field is considered representative of a certain
day, but the specification of exactly how the field is representative is
complex. This, to me, is not quite the same as saying that the field
represents 12 noon on that day, plus or minus 12 hours. It's more
"imprecision" than "uncertainty".
Would you agree with this distinction?
Cheers, Jon
-----Original Message-----
From: McCann, Mike [mailto:[email protected]]
Sent: 03 June 2010 19:47
To: Jon Blower; Steve Hankin
Cc: [email protected]
Subject: Re: [CF-metadata] bounds/precision for time axis
Hi Jon,
The OceanSITES data management team has recognized a desire to include
an
attribute named "uncertainty" for all of our in situ measurements that
are
in our netCDF files (that also follow the CF convention).
We chose the attribute "uncertainty" after much discussion around terms
such
as "precision" and "accuracy" because we felt that "uncertainty"
encompasses
several aspects of metrology and is more usable and simple to understand
for
the consumers of the data.
This attribute can also be extended to the coordinate variables, e.g. If
the
precision of my clock and upstream sampling techniques was 5 seconds I'd
assign 5 to the .uncertainty attribute on my time coordinate.
Would this approach work for your data?
-Mike
--
*******************************************************
* Nan Galbraith (508) 289-2444 *
* Upper Ocean Processes Group Mail Stop 29 *
* Woods Hole Oceanographic Institution *
* Woods Hole, MA 02543 *
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