On Mon, Jan 7, 2013 at 9:37 AM, John Wilkin (IMCS) <jwilkin at rutgers.edu> wrote:
> But by main issue is that in Example 7.8 the "time" data entered in
> the file is still described as having units "days since 1960-1-1"
> which really isn't so. It is equally logically "days since 1991-1-1".
> In reality it's just "days since Jan 1 of any year".
> So it seems a standard for expressing climatology time needs some thought.
Indeed -- there was a discussion about this a while back on this list,
started by how/whether to deal with non-constant time units, like
"months since" or "years since".
I thought then, and still do, that things like "monthly averages" are
really categorical, rather than traditional time units -- we generally
assume time is something that is an axis that is monotonically
increasing, values on that axis have nice properties like
differentiability, etc.
Yes, we use similar units (month names, etc) for categorical data as
for continuous time data, but if we try to shoehorn the categorical
data into the same conventions used for other time axis we are simply
asking for mis-interpretation and errors.
We need a different way to represent this stuff.
-Chris
--
Christopher Barker, Ph.D.
Oceanographer
Emergency Response Division
NOAA/NOS/OR&R (206) 526-6959 voice
7600 Sand Point Way NE (206) 526-6329 fax
Seattle, WA 98115 (206) 526-6317 main reception
Chris.Barker at noaa.gov
Received on Mon Jan 07 2013 - 11:42:57 GMT
