Hi Philip, Very precicely speaking, what we propose is simulation of high/medium/low cloud area fractions following SYNOP rules. Some operational NWP models do a kind of simulation of cloud that would be observed by humans at surface. This is a kind of substitute of manned surface observation, so I believe it will be useful more and more.
Regarding generality. Some people may consider it roughly compatible with height-based definitions like ISCCP. It's up to users. But we have to make definition clear, mainly to avoid comments requesting use of vertical coordinate variable. Cloud type-based classifications doesn't have natural vertical coordinate, and new names are only necessary for such parameters. Height-based classifications can be described with existing standard name "cloud_area_fraction" with vertical coordinate variable. Synoptic observation (coordinated by WMO) is probably only well-known type-based classification. And it has been unchanged at least since 1975, and I personally think it isn't likely to change for many years. Above is my understanding but I believe and hope original proposal from Heiko is not too far from that. So now I see no problem to register high/middle/low_type_cloud_area_fraction . Best Regards, Eizi ----- Original Message ----- From: Cameron-smith, Philip To: Wright, Bruce ; [email protected] Sent: Wednesday, May 16, 2012 3:55 AM Subject: Re: [CF-metadata] FW: Standard_name for cloud-cover by phenomenon Thanks, Bruce. Those emails helped crystalize it for me. Heiko, Eizi, are you proposing that the definition of high/medium/low_type_cloud_area_fraction follow the SYNOP rules precisely? Or will it be general enough to allow similar protocols, eg from ISCCP? If it is highly specific then I still feel it would be better to include the provenance (eg, WMOSYNOP). If the definition will be somewhat general then I will drop my objection. I am still not enthusiastic about using the work 'type' in this way, but I confess that I cannot think of a better alternative. Best wishes, Philip ----------------------------------------------------------------------- Dr Philip Cameron-Smith, [email protected], Lawrence Livermore National Lab. ----------------------------------------------------------------------- From: [email protected] [mailto:[email protected]] On Behalf Of Wright, Bruce Sent: Tuesday, May 15, 2012 7:21 AM To: [email protected] Subject: [CF-metadata] FW: Standard_name for cloud-cover by phenomenon 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 thedifficulty experienced in the discussions here are a consequence ofmixing 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 andvisually on the Cloud Appreciation Society website at:http://cloudappreciationsociety.org/collecting/about-cloud-classifications/http://cloudappreciationsociety.org/collecting/ I believe that this allocation to height bands is sufficientlywell-known to be characterized without attributing an owner (e.g. WMO)or an observation process (e.g. SYNOP), as Heiko argued. Thus, (ifrequired) these should probably be given the standard names: low_type_cloud_area_fractionmedium_type_cloud_area_fractionhigh_type_cloud_area_fraction *However*, at present I would argue that these can only be accuratelydetermined by a human inspection of the sky, which leads us to thesecond concept... 2. Cloud Height Classification Based on Height Ranges Most automated systems, be they cloud base recorders, numerical modelsor other forecasting processes, will assign a cloud height class basedon a height range. In this case, I would argue that the following set ofstandard names are more appropriate: low_cloud_area_fractionmedium_cloud_area_fractionhigh_cloud_area_fraction I acknowledge that different height ranges will be adopted by differentusers, but, as Heiko states, this approach will at least allowIntercomparison, and the exact details of the height ranges used couldbe included as additional (non-CF Standard) metadata. Having presented these two 'concepts', I would suggest that the secondis likely to be the most useful, in an age where the human observers aresignificantly outnumbered by automated observing and forecastingsystems. However, there is no reason why both sets of standard namescould not to adopted. My contribution to the debate - I hope it's helpful. Regards, Bruce ------------------------------------------------------------------------------ _______________________________________________ CF-metadata mailing list [email protected] http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
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