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
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Received on Thu Sep 11 2014 - 10:04:28 BST
