Dear All,

In a project we are trying to come up with CF compliant description of a range 
of climate indices (aka indices of climate extremes, ...), of which most I 
would believe fall under the heading "7.4 Climatological statistics". This is 
not a new topic for this email list; there was an extensive email exchange back 
in 2007 on "[CF-metadata] statistic indices", and related questions and 
requests have popped up both before and after. CF standard and the variety of 
climate indices has evolved quite a bit since 2007.

As this is an extensive and diverse topic, and I am a newcomer to this list , I 
will start with a couple of specific and possibly simple questions:

1. Is there a standard name for "diurnal temperature range", or a combined 
standard name/cell method representation? Cf. the 2010 mail archive thread 
http://mailman.cgd.ucar.edu/pipermail/cf-metadata/2010/054016.html that added 
"range" to Appendix E.

2. 'Heating Degree Days' and similar: I take it this was resolved/decided to 
have standard name "integral_of_air_temperature_deficit_wrt_time" (or 
..._excess_...), with canonical units K s  in this post 
http://mailman.cgd.ucar.edu/pipermail/cf-metadata/2005/051014.html . However, 
as the threshold is not explicitly referred to in the standard name, how is 
this linkage formally established? A practical example would be helpful. 

3. Several of the standard names directly targeted at climate indices (e.g. 
"spell_length_.....", "number_of_days_...") are dimensionless because the unit 
is already included in the standard name. This is of course consistent and 
parsimonious in terms of describing the data. But with respect of a software 
package producing a plot that needs a legend with units attached, it is not 
very enlightening to have the unit "1". For example, in a map of Frost Days the 
title drawn from the long name or the comment may be something like "Number of 
Frost Days (Tmin < 0 degC)" but the color scale should preferably have units 
"days" rather than "1".  As this is not specific to climate indices, what is 
the CF accepted advice or solution to this?

4. In Example 7.13 I believe the unit for monthly max daily precip should be 
"kg m-2" and not "kg"?


Best regards,
Lars

--
Lars Bärring

FDr,Forskare         / Gästprofessor,CEC/Lunds universitet
PhD,Senior Scientist / Guest professor,CEC/Lund University

SMHI  /  Swedish Meteorological and Hydrological Institute 
Rossby Centre 
SE - 601 76 NORRKÖPING 
http://www.smhi.se

E-post / Email: [email protected]
Tel / Phone: +46 (0)11 495 8604  
Fax: +46 (0)11 495 8001 
Besöksadress / Visiting address: Folkborgsvägen 17


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