Not sure if this was reply from Karl, went to the whole list or just to me.
Regards, Bruce ________________________________ From: Karl Taylor [mailto:[email protected]] Sent: 15 May 2012 15:09 To: Wright, Bruce Subject: Re: [CF-metadata] Standard_name for cloud-cover by phenomenon All, Also, sorry to step in late and not having read all the communications on this ... but for your consideration: In Bruce's second case, wouldn't it be better to use a vertical coordinate (specifically the bounds on it) to indicate the cloud layer being considered? The standard name "cloud_area_fraction" could then be used, and the coordinate would tell whether it was low, middle, or high (and would also quantitatively specify what is meant by those qualitative terms). Best regards, Karl On 5/15/12 2:07 AM, Wright, Bruce wrote: All, Sorry to wade into this discussion late, but I believe part of the difficulty experienced in the discussions here are a consequence of mixing two distinct 'concepts': 1. Cloud Height Classification Based on Cloud Types There is a well-recognised allocations of cloud types to height-bands. These types and bands are nicely illustrated both in tabular form and visually on the Cloud Appreciation Society website at: http://cloudappreciationsociety.org/collecting/about-cloud-classificatio ns/ http://cloudappreciationsociety.org/collecting/ I believe that this allocation to height bands is sufficiently well-known to be characterized without attributing an owner (e.g. WMO) or an observation process (e.g. SYNOP), as Heiko argued. Thus, (if required) these should probably be given the standard names: low_type_cloud_area_fraction medium_type_cloud_area_fraction high_type_cloud_area_fraction *However*, at present I would argue that these can only be accurately determined by a human inspection of the sky, which leads us to the second concept... 2. Cloud Height Classification Based on Height Ranges Most automated systems, be they cloud base recorders, numerical models or other forecasting processes, will assign a cloud height class based on a height range. In this case, I would argue that the following set of standard names are more appropriate: low_cloud_area_fraction medium_cloud_area_fraction high_cloud_area_fraction I acknowledge that different height ranges will be adopted by different users, but, as Heiko states, this approach will at least allow Intercomparison, and the exact details of the height ranges used could be included as additional (non-CF Standard) metadata. Having presented these two 'concepts', I would suggest that the second is likely to be the most useful, in an age where the human observers are significantly outnumbered by automated observing and forecasting systems. However, there is no reason why both sets of standard names could not to adopted. My contribution to the debate - I hope it's helpful. Regards, Bruce
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