Hi,
So, it sounds like there is a need to extend the conventions to account
for this issue.
As a suggestion, how about specifying the climatological bounds (either
as Karl originally described or keeping the dates all within the full
time span) AND specifying the full time span with a standard time
bounds? Would that provide sufficient information?
Grace and peace,
Jim
On 2/15/16 7:02 AM, Hollis, Dan wrote:
Hi Karl,
This is a real use case for us too. And not just for short climatologies. When
we compute our 30-year normals we use only the data from those 30 calendar
years e.g. for 1981-2010 normals we use data from Jan 1981 to Dec 2010. Like
you we create monthly normals first and then combine these to create seasonal
normals. I'd not come up with a way to describe the result in a CF-compliant
way so I was interested to see your question.
Using daily maximum temperature as an example, I guess what we are doing is
something like this:
time: maximum within days time: mean over days time: mean over years
time: mean over months
where 'mean over days' means over the days within each calendar month
and 'mean over months' means over the months within a season
I cannot immediately see how to extend/adapt the convention to allow for this
possibility.
Regards,
Dan
-----Original Message-----
From: CF-metadata [mailto:cf-metadata-boun...@cgd.ucar.edu] On Behalf Of Karl
Taylor
Sent: 11 February 2016 20:50
To: cf-metadata@cgd.ucar.edu
Subject: Re: [CF-metadata] How to build CF-compliant seasonal climatology when
data begins within a season
Hi Jonathan,
Our thinking is the same on this. Thanks.
By the way it is a real use case and I think it is scientifically
defensible: I have 11 full years of data and I first compute a climatological
annual cycle, yielding 12 climatological months. Then I compute the climatology
for each of the seasons from the monthly climatology. This allows me to use
all the data in the 11 years. I especially would want to do it this way if I
only had 2 or 3 years of data because I wouldn't want to omit any of it.
[Of course you wouldn't be able to do this if you were calculating say a trend
of individual seasons; in that case you clearly wouldn't want to consider
partial seasons.]
best wishes,
Karl
On 2/11/16 12:20 PM, Jonathan Gregory wrote:
Dear Karl
I agree with Seth that this isn't anticipated by the design of the
convention, which assumes that the mean over seasons is composed of a
number of complete seasons. Is this a real use-case, with a DJF mean
made by including JF from one NH winter and D from another? It seems a
bit odd to me. I wouldn't compute a monthly mean of anything if 2/3 of
the days were missing in the month. But, following this logic, your
original choice of "1999-12-1" to "2011-3-1" is OK, and it "just
happens" that Dec 1999 and Jan-Feb 2011 are actually not included, as
if they were missing data. Their omission is not recorded by the
climatology bounds but, equally, if Dec 2005 or Jan-Feb 2008 (for
example) were missing when computing the mean you would not know about it from
the climatology bounds. So perhaps it doesn't matter.
To spell out exactly which months were used, it would be necessary to
record also the time coordinate and bounds before the collapse. In
various tickets we have discussed but not agreed a convention for doing that,
as extra info.
Alternatively you could record it as unstandardised info as a comment
in () in the cell_methods, as you note.
Best wishes
Jonathan
----- Forwarded message from Karl Taylor <taylo...@llnl.gov> -----
Date: Wed, 10 Feb 2016 15:37:01 -0800
From: Karl Taylor <taylo...@llnl.gov>
To: cf-metadata@cgd.ucar.edu
Subject: [CF-metadata] How to build CF-compliant seasonal climatology when
data begins within a season
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9; rv:38.0)
Gecko/20100101 Thunderbird/38.5.1
Dear CF community,
In representing the seasonal climatology based on data available for
the period January 1, 2000 through December 31 2010, what would be
the correct climatology_bounds?
climatology_bounds = "1999-12-1", "2011-3-1",
"2000-3-1", "2010-6-1",
"2000-6-1", "2010-9-1",
"2000-9-1", "2010-12-1" ????
I would note that this seems to capture the idea that we are
reporting seasonal means, but it also seems to indicate that this is
based in part on data from Dec. 1999 and Jan.-Feb. 2011, when it
isn't. Is this the best I can do? [Of course the convention can
never tell us if data are complete in forming a climatology. If 1
year were missing, this would not affect the attributes.]
I suppose the in the cell_methods attribute ("time: mean over days
time: mean over years" I could add non-standardized information (as
permitted by CF), for example: "time: mean over days time: mean
over years (with data from the period 2000-1-1 to 2011-1-1)"
thanks for any suggestions,
Karl
_______________________________________________
CF-metadata mailing list
CF-metadata@cgd.ucar.edu
http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
----- End forwarded message -----
_______________________________________________
CF-metadata mailing list
CF-metadata@cgd.ucar.edu
http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
_______________________________________________
CF-metadata mailing list
CF-metadata@cgd.ucar.edu
http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
_______________________________________________
CF-metadata mailing list
CF-metadata@cgd.ucar.edu
http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
--
CICS-NC <http://www.cicsnc.org/> Visit us on
Facebook <http://www.facebook.com/cicsnc> *Jim Biard*
*Research Scholar*
Cooperative Institute for Climate and Satellites NC <http://cicsnc.org/>
North Carolina State University <http://ncsu.edu/>
NOAA National Centers for Environmental Information <http://ncdc.noaa.gov/>
/formerly NOAA’s National Climatic Data Center/
151 Patton Ave, Asheville, NC 28801
e: jbi...@cicsnc.org <mailto:jbi...@cicsnc.org>
o: +1 828 271 4900
/Connect with us on Facebook for climate
<https://www.facebook.com/NOAANCEIclimate> and ocean and geophysics
<https://www.facebook.com/NOAANCEIoceangeo> information, and follow us
on Twitter at @NOAANCEIclimate <https://twitter.com/NOAANCEIclimate> and
@NOAANCEIocngeo <https://twitter.com/NOAANCEIocngeo>. /
_______________________________________________
CF-metadata mailing list
CF-metadata@cgd.ucar.edu
http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
