I'm very pleased to see this discussion taking place!
The issue of emissions height is important. In many cases there is insufficient data to clarify this, so it's rather ambiguous (some IND emissions will be low, some will be high stacks). So we need to be careful not to imply precision that doesn't exist. perhaps a standard should state that in the default case height is not specified, and perhaps give an alternative specification for those cases where the data do exist and height can be specified.
So I'm not sure it's a good idea to use the term surface in general, but there could have a variant where height is explicitly specified (this would currently be the case for aircraft emissions for example).
Cheers,
Steve
-----Original Message-----
From: Schultz, Martin [m.schultz at fz-juelich.de<mailto:m.schultz at fz-juelich.de>]
Sent: Wednesday, March 07, 2012 02:00 AM Pacific Standard Time
To: cf-metadata at cgd.ucar.edu
Cc: Smith, Steven J (PNNL-JGCRI); Gregory.J.Frost (Gregory.J.Frost at noaa.gov); hugo.deniervandergon at tno.nl
Subject: RE: Warming up old stuff - 4 (emissions)
Dear Alison (cc Hugo, Steve, Greg),
> Looking back to the original proposal,
> http://mailman.cgd.ucar.edu/pipermail/cf-metadata/2011/027071.html, you
> have provided definitions of the emissions sectors in terms of 2006 IPCC
> source categories. I have found the following document: http://www.ipcc-
> nggip.iges.or.jp/public/2006gl/pdf/1_Volume1/V1_8_Ch8_Reporting_Guida
> nce.pdf (section 8.5) which appears to contain the categories to which you
> refer. Please can you confirm whether this is the best reference to use as I
> think it will be important to include it in the definitions? Steve has supported
> your sector definitions and they are clearly in wide use. There have been no
> other comments regarding the categories.
This appears to be the right document. To make sure, I ask Hugo, Greg and Steve to confirm. I guess the official reference web site is
http://unfccc.int/national_reports/annex_i_ghg_inventories/items/2715.php, but that doesn't seem to offer the information in a single pdf file format.
> When the carbon_dioxide emission names were introduced there was some
> discussion as to whether to use
> 'tendency_of_atmosphere_mass_content_of_X_due_to_emission' or
> 'surface_upward_mass_flux_of_X_due_to_emission'. The units would be
> the same in either case (kg m-2 s-1) and the distinction is really one of where
> the emission takes place. The surface_upward_flux names apply only to
> emission at the surface itself and are therefore 2D fields. The tendency
> due_to_emission names refer to emission anywhere in the atmosphere,
> including the surface, and are 3D fields. Obviously your aviation emissions
> would be 3D, but is that also true of the others? I am happy to use either
> form of words in these names, whichever you feel is the most appropriate.
Back then we had decided on the 'tendency_of_atmosphere_mass_content...' terms, because there are various other sectors for which "surface" is not fully appropriate, such as smoke stacks from power plants and industrial facilities, and even ship emissions (where the chimney is typically at ~30 m altitude and therefore often falls into the second or even third model grid box above the surface. The term "surface_flux" suggests that these emissions are indeed formulated as a surface flux boundary condition (i.e. technically they are introduced into the diffusion equation), and this is not always the case. The change in atmospheric mass content is the ultimate result and the term is more universal and easily covers all "strange" 3D emissions as well. But of course it is a bit unfortunate that carbon emissions are then named different from other species. Where this makes sense, we could perhaps define alias names for the carbon fluxes?
Best regards,
Martin
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Received on Wed Mar 07 2012 - 06:54:26 GMT
