Dear Heiko, Philip, All,
Earlier this year Heiko Klein proposed the following three standard names for cloud:
high_type_cloud_area_fraction
medium_type_cloud_area_fraction
low_type_cloud_area_fraction
which received a considerable amount of discussion regarding both the names and their definitions.
Towards the end of the discussion (16th May) Philip Cameron-Smith asked two questions:
> Are there any other visual classification schemes in common use other than the current SYNOP one?
>
> Is the current SYNOP scheme likely to change significantly?
>
> This isn't my field, so I don't know the answers. If the answer to both questions is 'no', then I will drop all my objections.
No one responded directly to Philip's questions and Heiko asked on 11th June whether we could regard the names as accepted. I have now reviewed the full discussion and note that Eizi Toyoda stated (
http://mailman.cgd.ucar.edu/pipermail/cf-metadata/2012/055649.html) that the SYNOP scheme has remained unchanged since 1975 and was unlikely to do so in the near future, so I think we can take that as a 'no' to Philip's second question. Regarding Philip's first question, I note that Bruce Wright expressed the view (
http://mailman.cgd.ucar.edu/pipermail/cf-metadata/2012/055642.html) that the classification scheme is sufficiently widely used that it doesn't need to be attributed to any particular 'owner'. I have also confirmed with Heiko (offlist) that there isn't any 'competitor' to the SYNOP classification, so I think we can also answer 'no' to the first question.
As there are no further outstanding objections to these names, they are now accepted for addition to the standard name table.
Based on the definition of the existing cloud_area_fraction name and the discussion of the proposed names I have written definitions as follows:
high_type_cloud_area_fraction: ' High type clouds are: Cirrus, Cirrostratus, Cirrocumulus. "X_area_fraction" means the fraction of horizontal area occupied by X. Cloud area fraction is also called "cloud amount" and "cloud cover". X_type_cloud_area_fraction is determined on the basis of cloud type and not on the vertical location of the cloud.'
medium_type_cloud_area_fraction: 'Middle type clouds are: Altostratus, Altocumulus, Nimbostratus. "X_area_fraction" means the fraction of horizontal area occupied by X. Cloud area fraction is also called "cloud amount" and "cloud cover". X_type_cloud_area_fraction is determined on the basis of cloud type and not on the vertical location of the cloud.'
low_type_cloud_area_fraction: ' Low type clouds are: Stratus, Stratocumulus, Cumulus, Cumulonimbus. "X_area_fraction" means the fraction of horizontal area occupied by X. Cloud area fraction is also called "cloud amount" and "cloud cover". X_type_cloud_area_fraction is determined on the basis of cloud type and not on the vertical location of the cloud.'
These names and definitions will be added at the next update of the standard name table.
Best wishes,
Alison
------
Alison Pamment Tel: +44 1235 778065
NCAS/British Atmospheric Data Centre Email: alison.pamment at stfc.ac.uk
STFC Rutherford Appleton Laboratory
R25, 2.22
Harwell Oxford, Didcot, OX11 0QX, U.K.
> -----Original Message-----
> From: CF-metadata [mailto:cf-metadata-bounces at cgd.ucar.edu] On Behalf
> Of Heiko Klein
> Sent: 11 June 2012 09:41
> To: Cameron-smith, Philip
> Cc: cf-metadata at cgd.ucar.edu
> Subject: Re: [CF-metadata] FW: Standard_name for cloud-cover by
> phenomenon
>
> Hi All,
>
> after 3 weeks of silence on this subject, I assume there was no-one who
> answered with 'yes' to Philips questions, and there are no longer
> objections on using the standardard-names:
>
> low_type_cloud_area_fraction
> medium_type_cloud_area_fraction
> high_type_cloud_area_fraction
>
>
> Can I hope for these standard-names to appear in the next version of
> standard-names?
>
> Best regards,
>
> Heiko
>
> On 2012-05-16 19:08, Cameron-smith, Philip wrote:
> > Hi All,
> >
> > I just refreshed my memory of ISCCP, and I should not have been using it
> > as an example in the way that I did (my apologies).
> >
> > Are there any other visual classification schemes in common use other
> > than the current SYNOP one?
> >
> > Is the current SYNOP scheme likely to change significantly?
> >
> > This isn't my field, so I don't know the answers. If the answer to both
> > questions is 'no', then I will drop all my objections.
> >
> > If the answer to either question is 'yes', then I would suggest that
> > either the description be general enough to cover the different schemes,
> > or we return to the idea of putting the name of the scheme into the
> > std_name.
> >
> > Best wishes to all,
> >
> > Philip
> >
> > -----------------------------------------------------------------------
> >
> > Dr Philip Cameron-Smith, pjc at llnl.gov, Lawrence Livermore National Lab.
> >
> > -----------------------------------------------------------------------
> >
> > *From:*TOYODA Eizi [mailto:toyoda at gfd-dennou.org]
> > *Sent:* Tuesday, May 15, 2012 10:42 PM
> > *To:* Cameron-smith, Philip; Wright, Bruce; cf-metadata at cgd.ucar.edu
> > *Subject:* Re: [CF-metadata] FW: Standard_name for cloud-cover by
> phenomenon
> >
> > 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
> > <http://cf-pcmdi.llnl.gov/documents/cf-standard-names/standard-name-
> table/19/cf-standard-name-table.html>"
> > 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 <mailto:cameronsmith1 at llnl.gov>
> >
> > *To:*Wright, Bruce <mailto:bruce.wright at metoffice.gov.uk> ;
> > cf-metadata at cgd.ucar.edu <mailto:cf-metadata at cgd.ucar.edu>
> >
> > *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, pjc at llnl.gov, Lawrence Livermore National
> Lab.
> >
> > -----------------------------------------------------------------------
> >
> > *From:*cf-metadata-bounces at cgd.ucar.edu
> > [mailto:cf-metadata-bounces at cgd.ucar.edu] *On Behalf Of *Wright,
> Bruce
> > *Sent:* Tuesday, May 15, 2012 7:21 AM
> > *To:* cf-metadata at cgd.ucar.edu
> > *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:taylor13 at llnl.gov]
> > *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
> >
> > ------------------------------------------------------------------------
> >
> > _______________________________________________
> > CF-metadata mailing list
> > CF-metadata at cgd.ucar.edu
> > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
> >
> >
> >
> > _______________________________________________
> > CF-metadata mailing list
> > CF-metadata at cgd.ucar.edu
> > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
> >
>
> --
> Dr. Heiko Klein Tel. + 47 22 96 32 58
> Development Section / IT Department Fax. + 47 22 69 63 55
> Norwegian Meteorological Institute http://www.met.no
> P.O. Box 43 Blindern 0313 Oslo NORWAY
>
>
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Received on Thu Dec 06 2012 - 05:26:17 GMT
