[CF-metadata] Standard_name for cloud-cover by phenomenon

TOYODA Eizi toyoda at gfd-dennou.org
Wed Apr 25 05:20:37 MDT 2012


Hello David,

Cloud types (lo/mid/hi) of ISCCP described at 
http://isccp.giss.nasa.gov/cloudtypes.html is classification of height of 
cloud, observed in infrared image of satellite.

Heiko is talking about cloud types of the same name, but it's NWP product. 
They are not necesarily matching to satellite-based classification, rather 
tuned to imitate classical cloud types, so that the product can be used as 
substitute of cloud cover in synoptic station reports.  For example, if 
convection is forecast, that will be classified as "low cloud", no matter 
how high the top of the cloud reaches.

Best Regards,
-- 
TOYODA Eizi, Japan Meteorological Agency

----- Original Message ----- 
From: "David Hassell" <d.c.hassell at reading.ac.uk>
To: "Heiko Klein" <Heiko.Klein at met.no>
Cc: <cf-metadata at cgd.ucar.edu>
Sent: Wednesday, April 25, 2012 7:36 PM
Subject: Re: [CF-metadata] Standard_name for cloud-cover by phenomenon


> Hello Heiko,
>
> I don't have a strong opinion, but am just testing the water ...
>
> I wonder how one would define these standard names so that they were
> correct for all uses, for example from a three layer model to the
> ISCCP datasets.
>
> In your example, would a model_level_number coordinate of [1, 2, 3]
> fit your needs, possibly with an auxiliary coordinate of ['low',
> 'medium', 'high']? Would we need a standard name for the auxiliary
> coordinate, or would a long name suffice?
>
> All the best,
>
> David
>
> ---- Original message from Heiko Klein (11AM 25 Apr 12)
>
>> Date: Wed, 25 Apr 2012 11:49:06 +0200
>> From: Heiko Klein <Heiko.Klein at met.no>
>> User-Agent: Mozilla/5.0 (X11; Linux i686; rv:11.0) Gecko/20120327
>>  Thunderbird/11.0.1
>> To: "cf-metadata at cgd.ucar.edu" <cf-metadata at cgd.ucar.edu>
>> Subject: [CF-metadata] Standard_name for cloud-cover by phenomenon
>>
>> Hei,
>>
>> in grib, clouds are described as low, medium and high clouds, e.g.
>> 73,74,75. Those are described by phenomenon, e.g.
>>
>> high cloud type:  Clouds of genera Cirrus, Cirrocumulus and Cirrostratus.
>>
>> low cloud type: Clouds of genera Stratocumulus, Stratus, Cumulus, etc.
>>
>> medium cloud type: Clouds of the genera Altocumulus, Altostratus, etc.
>>
>> (see
>>
>> In CF, this can currently only be expressed by
>> cloud_area_fraction_in_atmosphere_layer and a not very well defined
>> 'vertical' parameter, e.g. by sigma:
>> http://www.ecmwf.int/products/data/archive/data_faq.html#clouddefinitions
>>
>>
>> When translating from grib to CF, this is not very satisfying:
>> Either I add some dummy sigma-values, which will look like I have a
>> model with just three levels, or I use 3 variables, all with the
>> same 'standard_name="cloud_area_fraction"' which looses some useful
>> information. In both cases, the data-user will need to know
>> something which cannot be expressed by CF.
>>
>>
>> Looking at the page
>> http://cf-pcmdi.llnl.gov/documents/cf-standard-names/ecmwf-grib-mapping
>> there are mentioned 3 'standard_names' which are not in the
>> standard_name-table yet, and I propose to do so:
>>
>> low_cloud_area_fraction
>> medium_cloud_area_fraction
>> high_cloud_area_fraction
>>
>> in additon (though this is not in grib), I would like to add
>> fog_area_fraction (or surface_cloud_area_fraction).
>>
>>
>> Best regards,
>>
>> Heiko
>>
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>
>
> --
> David Hassell
> National Centre for Atmospheric Science (NCAS)
> Department of Meteorology, University of Reading,
> Earley Gate, PO Box 243,
> Reading RG6 6BB, U.K.
>
> Tel   : 0118 3785613
> Fax   : 0118 3788316
> E-mail: d.c.hassell at reading.ac.uk
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