resending to the list, a bit belatedly...
Hi Dan,
There is no way to search the CF-metadata archives directly that I know of.
I tried using a little Google-fu to do a site search, entering
site:
http://mailman.cgd.ucar.edu/pipermail/cf-metadata/ "above_threshold"
finds five matches:
http://mailman.cgd.ucar.edu/pipermail/cf-metadata/2007/051858.html
But my internal email search finds lots more. Anyone know what's up with that? Looks like a Google fail to me.
I looked in my collection for all the related posts, and did not find any discussing this situation, which involves a bit of a tradeoff. I prefer either of these options:
- Create new standard names using 'at_or_above_threshold' (not as over the top as it feels, really)
- Create a boolean attribute "include_instances_matching_threshold" (this would be generic for all 'above|below_threshold' names, and simplifies searches against the standard name)
If you declare the thresholds as slightly lower, as you suggest, you may have to change them when the measurements are more precise, and it just all gets rather messy.
John
On Aug 28, 2014, at 02:31, Hollis, Dan <dan.hollis at metoffice.gov.uk> wrote:
> Hi,
>
> Another question relating to our work on migrating gridded UK observations data to NetCDF?
>
> We have several variables that we describe loosely as 'days of rain'. Strictly speaking they are a count (e.g. for a calendar month) of the number of days when the 24-hour precipitation total was greater than or equal to a threshold. We currently generate grids for three thresholds - 0.2mm, 1.0mm and 10.0mm. My intention is to use the following existing standard name:
>
> number_of_days_with_lwe_thickness_of_precipitation_amount_above_threshold
>
> My only slight problem is that the definition implies 'greater than' whereas our variables are 'greater than or equal to' the threshold. Assuming the observations have a precision of 0.1 mm (which is true for the UK) I could declare the thresholds to be 0.1mm, 0.9mm and 9.9mm respectively. Alternatively, to avoid the assumption about precision I could use 0.19999mm, 0.99999mm and 9.99999mm.
>
> Neither option seems very elegant or satisfactory. To define new standard name(s) seems over the top. What advice would others give? Is there a way to adapt the existing threshold variables (there are currently 8, relating to air temperature, precipitation and wind speed) to cope with both 'greater/less than' and 'greater/less than or equal to', or should I just use one of my solutions given above?
>
> Thanks,
>
> Dan
>
> PS I appreciate this topic may have been discussed before, however I can't seem to find a way to search the mailing list archives. Is this possible and if so how? Thanks.
>
>
> Dan Hollis Climatologist
> Met Office Hadley Centre FitzRoy Road Exeter Devon EX1 3PB United Kingdom
> Tel: +44 (0)1392 886780 Fax: +44 (0)1392 885681
> E-mail: dan.hollis at metoffice.gov.uk Website: http://www.metoffice.gov.uk
> For UK climate and past weather information, visit http://www.metoffice.gov.uk/climate
>
>
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Received on Tue Sep 02 2014 - 22:23:53 BST
