Hi,
I have been following this thread with great interest and would
like to add my two cents.
I work with data that is reported at 15-second intervals and, in
the not too distant future, am expecting to be working with data
reported at 1-second intervals. One of my goals is to find
correlations, in the time domain, among different observables, as
measured by different data providers. It is essential that we speak a
common language when we talk about time.
Having worked with different computer languages, I've realized
they all have a different internal representation of elapsed time (both
level of granularity and reference "zero") and different libraries to
perform time transformations and computations. I would pose the
question: Is the recording of an elapsed time within netCDF a requirement?
Consider this alternative: For an
observationalist/experimentalist, many of today's data acquisition
systems are synchronized with the Global Positioning System, and,
specifically, timestamps are assigned using UTC (including leap
seconds). I would argue the most interoperable form of these timestamps
is that defined by an ISO 8601 standard, and more tightly constrained by
the IETF RFC 3339 profile (e.g. "YYYY-MM-DDTHH:mm:ss.sssZ"). In my
mind, timestamps are simply labels that allow one to match up disparate
observations in the hopes of revealing cause and effect in the real
world. If data providers record ISO 8601 timestamps as strings in
netCDF, then we have some hope of avoiding the pitfalls of one provider
transforming these to elapsed times with leap seconds and another
provider transforming to elapsed times without leap seconds.
Furthermore, if I am working with multiple data sets created by
different providers and I want to perform time computations (difference,
double-difference, etc.), I will use whatever library is provided by my
computer language of choice to transform from a time label to an elapsed
time, without having to worry about whether a data provider has computed
elapsed time in the same way as another provider. Essentially, I'm doing
that step myself.
I realize many people are attached to the idea of elapsed time as
a fundamental coordinate, but I have never heard a strong argument in
its favor.
Thank you for your kind consideration.
Cordially,
Aaron
--
Aaron D. Sweeney
Water Level Data Manager
Cooperative Institute for Research in Environmental Sciences (CIRES)
University of Colorado at Boulder
and
NOAA National Centers for Environmental Information
(formerly NOAA's National Geophysical Data Center)
325 Broadway, E/GC3
Boulder, CO 80305-3328
Phone: 303-497-4797, Fax: 303-497-6513
DISCLAIMER: The contents of this message are mine personally and do not necessarily reflect any position of NOAA.
Received on Fri Jun 26 2015 - 11:37:55 BST
