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 ; 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
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
CF-metadata at cgd.ucar.edu
http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <
http://mailman.cgd.ucar.edu/pipermail/cf-metadata/attachments/20120516/70f82c0d/attachment-0001.html>
Received on Tue May 15 2012 - 23:42:27 BST
