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
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