Hi Jonathan,
I found the list on the CF web site here:
http://cfconventions.org/Data/cf-standard-names/docs/area-type-table.html
However this looks to be much shorter than the list on github so I guess it needs updating.
The only references to area_type in the CF conventions doc (v1.6) appear to be in section 7.3.3 Statistics applying to portions of cells. However our data are point values (obtained by interpolating point observations) so we are not defining bounds for the spatial coordinates and therefore do not have a cell method for 'area'. Is it still possible to use area_type as a coordinate variable in this situation? E.g.
x=180
y=290
time=UNLIMITED
ntypes=1
maxlen=20
lat(y,x)
lon(y,x)
surface_type(ntypes,maxlen)
surface_type:standard_name="area_type"
surface_type="grass"
surface_temperature(time,ntypes,y,x)
surface_temperature:coordinates = "lat lon surface_type"
surface_temperature:cell_methods = "time: minimum within days time: mean over days"
Personally I'm not that keen on having to add a dimension, especially when surface type doesn't really feel like a dimension to me. However, assuming this (or some variant of it) is valid then I think it would be useful to add an example to the conventions doc. As area_type is being used only as an auxiliary coordinate variable and not within the cell methods presumably it would need to go somewhere other than section 7.3.
Regards,
Dan
-----Original Message-----
From: CF-metadata [mailto:cf-metadata-bounces at cgd.ucar.edu] On Behalf Of Jonathan Gregory
Sent: 11 September 2014 17:39
To: cf-metadata at cgd.ucar.edu
Subject: [CF-metadata] New standard name: number_of_days_with_surface_temperature_below_threshold
Dear Dan
The surface type can be described by using a coordinate or scalar coordinate
variable with a standard_name of area_type. You may need to request new
area types. This is a controlled CF vocabulary, like the standard names.
I can only find the area type table in XML on the new CF website. It used
to be in HTML as well. It is at
http://cf-convention.github.io/Data/cf-standard-names/27/src/area-type-table.xml
Best wishes
Jonathan
----- Forwarded message from "Hollis, Dan" <dan.hollis at metoffice.gov.uk> -----
> From: "Hollis, Dan" <dan.hollis at metoffice.gov.uk>
> To: "'alison.pamment at stfc.ac.uk'" <alison.pamment at stfc.ac.uk>, "Gregory,
> Jonathan" <j.m.gregory at reading.ac.uk>, "cf-metadata at cgd.ucar.edu"
> <cf-metadata at cgd.ucar.edu>
> Subject: RE: [CF-metadata] New standard name:
> number_of_days_with_surface_temperature_below_threshold
> Date: Thu, 11 Sep 2014 16:04:28 +0000
>
> Hi Alison, Jonathan, all
>
> I was discussing this request with some colleagues yesterday and someone asked how 'surface' was defined. The definition for 'surface_temperature' simply says:
>
> "The surface called "surface" means the lower boundary of the atmosphere. The surface temperature is the temperature at the interface, not the bulk temperature of the medium above or below."
>
> This is exactly what we want, except for the fact that the *type* of surface is undefined.
>
> My original request related to days of ground frost (i.e. grass minimum temperature below zero) simply because this is one of our routine variables and therefore near the top of the list of data sets to convert to NetCDF. However we also have grids of the number of days of concrete frost (computed from minimum temperature observations from a thermometer with its bulb in contact with a concrete slab). These will have different characteristics to the grass minimum values and therefore the two fields should not be combined/compared without knowing that the surface type is different.
>
> What is the correct way to define/declare the surface type? We think this issue must also apply to model data and that therefore someone may have already answered this question. Furthermore, given that models can generate fields of *air* temperature for different uniform surface types (grass, forest, urban etc) we wondered if the need to declare a surface type might also apply to 'air_temperature'. As well as uniform types there would also need to be a type of 'real land cover' (which is what we'd need for our data). Any suggestions?
>
> Regards,
>
> Dan
>
>
> -----Original Message-----
> From: CF-metadata [mailto:cf-metadata-bounces at cgd.ucar.edu] On Behalf Of Hollis, Dan
> Sent: 04 September 2014 11:16
> To: 'alison.pamment at stfc.ac.uk'; Gregory, Jonathan; cf-metadata at cgd.ucar.edu
> Subject: Re: [CF-metadata] New standard name: number_of_days_with_surface_temperature_below_threshold
>
> Hi Alison,
>
> Many thanks for clarifying how the process works. I look forward to the new name being added in due course.
>
> Regards,
>
> Dan
>
> -----Original Message-----
> From: alison.pamment at stfc.ac.uk [mailto:alison.pamment at stfc.ac.uk]
> Sent: 03 September 2014 13:07
> To: Hollis, Dan; Gregory, Jonathan; cf-metadata at cgd.ucar.edu
> Subject: RE: [CF-metadata] New standard name: number_of_days_with_surface_temperature_below_threshold
>
> Dear Dan,
>
> Thanks for your standard name proposal - you have done all that is necessary for it to be 'picked up'. I am the person responsible for updating the standard name table (the latest version can be viewed on the CF website at http://cfconventions.org/Data/cf-standard-names/27/build/cf-standard-name-table.html). I also maintain a list of proposals that are in the pipeline, so to speak, which is linked from the website 'Discussions' page (http://cfconventions.org/discussion.html) or can be viewed directly at
> http://cfeditor.ceda.ac.uk/proposals/1?status=active&namefilter=&proposerfilter=&descfilter=&filter+and+display=filter. Your proposal has been added to this list. (N.B. I am also in the process of adding other recent proposals to bring the list up to date as it hasn't been done for a while).
>
> I agree with Jonathan that your proposal for number_of_days_with_surface_temperature_below_threshold is fine and since it is so similar to an existing name I think that unless anyone raises any objections within the next week it can be accepted for publication in the standard name table.
>
> Best wishes,
> Alison
>
> ------
> Alison Pamment Tel: +44 1235 778065
> NCAS/British Atmospheric Data Centre Email: alison.pamment at stfc.ac.uk
> STFC Rutherford Appleton Laboratory
> R25, 2.22
> Harwell Oxford, Didcot, OX11 0QX, U.K.
>
>
> > -----Original Message-----
> > From: Hollis, Dan [mailto:dan.hollis at metoffice.gov.uk]
> > Sent: 03 September 2014 11:20
> > To: Gregory, Jonathan; cf-metadata at cgd.ucar.edu
> > Subject: Re: [CF-metadata] New standard name:
> > number_of_days_with_surface_temperature_below_threshold
> >
> > Hi Jonathan,
> >
> > Thanks for your support for the proposed standard name.
> >
> > I'm new to this process. I appreciate more time needs to be given to allow
> > others to comment but I was wondering if there is anything else I need to
> > do i.e. assuming there are no objections raised via the mailing list will the
> > Standard Names Committee pick this up automatically and add it to the next
> > release?
> >
> > Regards,
> >
> > Dan
> >
> >
> > -----Original Message-----
> > From: CF-metadata [mailto:cf-metadata-bounces at cgd.ucar.edu] On Behalf
> > Of Jonathan Gregory
> > Sent: 01 September 2014 17:36
> > To: cf-metadata at cgd.ucar.edu
> > Subject: [CF-metadata] New standard name:
> > number_of_days_with_surface_temperature_below_threshold
> >
> > Dear Dan
> >
> > > number_of_days_with_surface_temperature_below_threshold
> > >
> > > The definition would be similar to that for the existing standard name
> > 'number_of_days_with_air_temperature_below_threshold', the only
> > difference being that it would relate to surface temperature rather than air
> > temperature. We require this to allow us to store values of the number of
> > days of ground frost i.e. the number of days when the grass minimum
> > temperature (= surface temperature) dropped below 0 degC. Following the
> > approach for air temperature, the threshold would be specified via a
> > coordinate variable called 'surface_temperature'.
> >
> > That seems fine to me. Thanks for your efforts to convert to CF.
> >
> > Cheers
> >
> > Jonathan
> > _______________________________________________
> > CF-metadata mailing list
> > CF-metadata at cgd.ucar.edu
> > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
> > _______________________________________________
> > CF-metadata mailing list
> > CF-metadata at cgd.ucar.edu
> > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
> --
> Scanned by iCritical.
> _______________________________________________
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> CF-metadata at cgd.ucar.edu
> http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
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Received on Fri Sep 12 2014 - 04:27:54 BST
