Philip,
I agree that referring to versioned std_name tables is generally a good
idea. The WMO members have (and still have) problems with versioning, in
particularly when I think about grib-tables.
I still have a bad feeling about using a name like
wmosynop_high_cloud_area_fraction or isccp_high_cloud_area_fraction in
particularly since they give a over-specification of a generally well
understood phenomenons. Both wmosynop and isccp are
measurements/measurement networks, and CF generally does not have enough
metadata to cover all measurement-details. E.g. for air-temperature, it
is from a measurement point of view often important what type of
instrument has been measuring it (automatic, human, scale,...). We don't
have a 'human_quicksilver_air_temperature' in CF (or a
wmosynop_air_temperature). For comparing 'air_temperature' between
measurements and possibly different models, the generally understood
'air_temperature' is best.
With high-clouds, this is a similar problem. high, medium and low clouds
is generally well understood and well documented in literature (a simple
search on the net gives more than enough hits).
From a model point of view, I cannot estimate if a cloud is exactly the
one type or the other. There are often estimations like:
sigma < 0.4 -> high cloud
0.4 > sigma > 0.7 -> medium cloud
sigma > 0.7 -> low cloud
It will be difficult for the modeller to say: This is a cloud according
to the wmosynop definition.
Therefore, I think we need at first a general CF-name for
high/medium/low cloud to be able to compare in between measurement
networks and models. ISCCP, WMO synop and models have already the
concept of these clouds, they are not a 100% match, but close enough.
If then one of these networks needs a more exact definition of
high/medium/low clouds, they should ask for a std_name of their own.
Best regards,
Heiko
On 2012-05-14 22:59, Cameron-smith, Philip wrote:
Hi Heiko, Eizi,
You make a good point that any standard, such as WMO or ISCCP, may change.
However that is also true for CF, and furthermore I think it is likely that
other people will want other cloud description standards in the future,
including any changes to your WMO-synop standard.
My suggestion for dealing with this is to use the name of the cloud standard in
the CF std_name, and then put details and a version number in the std_name
description. This will make it precise, and easily extendable in the future.
BTW, I didn't immediately recognize what you meant by 'synop', although it
became more obvious after a quick google search. It initially sounded to me
like it was a non-specific reference to synoptic scales. If we do decide to
use it as part of the std_name, would it be appropriate to call it 'wmosynop'
or 'wmo_synop'?
Best wishes,
Philip
-----------------------------------------------------------------------
Dr Philip Cameron-Smith, [email protected], Lawrence Livermore National Lab.
-----------------------------------------------------------------------
-----Original Message-----
From: TOYODA Eizi [mailto:[email protected]]
Sent: Monday, May 14, 2012 1:12 AM
To: Heiko Klein
Cc: Cameron-smith, Philip; Jonathan Gregory; [email protected]
Subject: Re: [CF-metadata] Standard_name for cloud-cover by phenomenon
Hi Heiko,
Sorry about perturbing.
You're right. Currently nobody has requested other "low cloud fraction
area" such as ISCCP's.
And I should have add one thing: "low cloud" in ISCCP is simply defined
using height, so it is possible to describe it using vertical axis.
Our
synop case is different.
Best Regards,
Eizi
----- Original Message -----
From: "Heiko Klein"<[email protected]>
To: "TOYODA Eizi"<[email protected]>
Cc: "Cameron-smith, Philip"<[email protected]>; "Jonathan
Gregory"
<[email protected]>;<[email protected]>
Sent: Monday, May 14, 2012 4:01 PM
Subject: Re: [CF-metadata] Standard_name for cloud-cover by phenomenon
Hi,
the idea of putting a source of the definition to the name makes
sense if
you want to include several definitions. This is the case for
cloud_area_fraction and isccp_cloud_area_fraction. So, if we had
already
one definition of high_clouds, I would go for the SYNOP_high_clouds.
But
we currently don't have several definitions, and CF should make it's
own
one. And we currently agree very well on which definition to use.
I don't like the idea of putting the responsibility for the
definition
into others hands. If the SYNOP definition changes, the CF-definition
should not. CF-definitions should be self-describing and not rely on
other
parties.
Even if we used a prefix, we would still need the 'type' as discussed
in
the beginning of this thread, i.e. because high is neither altitude
nor
height, but a implicit name. So I would currently still prefer
high_type_cloud_area_fraction
middle_type_cloud_area_fraction
low_type_cloud_area_fraction
Best regards,
Heiko
On 2012-05-13 20:12, TOYODA Eizi wrote:
Hi Philip,
Your idea makes sense at least for me.
My bottom line is to avoid being forced to use vertical axis to
identify
types of clouds.
One thing: WMO is umbrella for too many programmes. So it is a bit
unclear to specify cloud definitions in operational synoptic
meteorology. So following might be clearer.
SYNOP_high_cloud_area_fraction
SYNOP_middle_cloud_area_fraction
SYNOP_low_cloud_fraction
(Heiko, what do you think? ?)
Eizi
----- Original Message ----- From: "Cameron-smith, Philip"
<[email protected]>
To: "Jonathan Gregory"<[email protected]>;
<[email protected]>
Sent: Friday, May 11, 2012 4:19 PM
Subject: Re: [CF-metadata] Standard_name for cloud-cover by
phenomenon
Hi All,
I am not wild about using 'type'. I had to read the terms several
times before I figured out what was being meant, because I could
read
it different grammatical ways.
A second problem is that it seems a particular definition will be
linked to these terms (or did I miss something?), yet someone might
reasonably want to use a different definition for high/middle/low
clouds in the future.
Although I generally don't like including the origin of the data in
the std_name, I think this may be an exception. I would suggest
using
either
ISCCP_high_cloud_area_fraction
ISCCP_middle_cloud_area_fraction
ISCCP_low_cloud_fraction
or
WMO_high_cloud_area_fraction
WMO_middle_cloud_area_fraction
WMO_low_cloud_fraction
I note that isccp_cloud_area_fraction is already an accepted
std_name,
so the suggestions above follow naturally.
This would also allow changes to the high/middle/low definitions in
the future. This would be a problem if there is a proliferation of
definitions, but I doubt this will be a problem.
Best wishes,
Philip
-------------------------------------------------------------------
----
Dr Philip Cameron-Smith, [email protected], Lawrence Livermore National
Lab.
-------------------------------------------------------------------
----
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Jonathan
Gregory
Sent: Tuesday, May 08, 2012 7:10 AM
To: [email protected]
Subject: Re: [CF-metadata] Standard_name for cloud-cover by
phenomenon
Dear Heiko
I just had a short side-discussion with Eizi, and we settled on
'type', i.e. we propose the standard names:
high_type_cloud_area_fraction
middle_type_cloud_area_fraction
low_type_cloud_area_fraction
These look fine to me. As you said to John, I hope that "type"
would
trigger
people to look up the definition.
Best wishes and thanks
Jonathan
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--
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
--
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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