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" <[email protected]>
To: "Heiko Klein" <[email protected]>
Cc: <[email protected]>
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 <[email protected]>
User-Agent: Mozilla/5.0 (X11; Linux i686; rv:11.0) Gecko/20120327
Thunderbird/11.0.1
To: "[email protected]" <[email protected]>
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
_______________________________________________
CF-metadata mailing list
[email protected]
http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
--
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: [email protected]
_______________________________________________
CF-metadata mailing list
[email protected]
http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
_______________________________________________
CF-metadata mailing list
[email protected]
http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
