Hi All,
I have a few concerns.
1) Normally std_names are for quantities which both models and observations try to calculate/measure. What is being proposed here is a std_name that includes the method of calculation/measurement. Such std_names have long been controversial, so there is usually a higher bar for their acceptance. Is the condition that the calculation assume Mie scattering really important? If it is just that a model happens to calculate scattering by assuming Mie theory, then I would prefer NOT to have such a std_name, and instead use _due_to_ambient_aerosol and note the model assumptions in a comment field'
2) I think both _extinction_ and _scattering_ could make sense, so the question is "which is actually needed"?
3) Note my next email about _extinction_ and _attenuation_.
Best wishes,
Philip
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Dr Philip Cameron-Smith, pjc at llnl.gov, Lawrence Livermore National Lab.
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> -----Original Message-----
> From: cf-metadata-bounces at cgd.ucar.edu [mailto:cf-metadata-
> bounces at cgd.ucar.edu] On Behalf Of Markus Fiebig
> Sent: Friday, March 09, 2012 1:03 AM
> To: Shankar, Uma; X:m.schultz at fz-juelich.de; cf-metadata at cgd.ucar.edu
> Subject: Re: [CF-metadata] warming up old stuff - part 1: aerosol mie
> scattering
>
> Hi Uma,
>
> thanks for your interest!
>
> The type of observations I'm concerned with are not only aerosol
> optical depth (AOD) as column integrated property, but also ground-
> based in-situ observations of particle size distribution, scattering
> and absorption coefficient that are representative for the surface
> level. These are usually measured at "dry-state", i.e. at RH < 40%
> where aerosol humidity growth is negligible.
>
> Traditionally, model-observation comparisons have relied on AOD
> observations since AOD is a diagnostic parameter, it's usually output
> directly by the model, and it can be measured directly. The other
> observations I'm talking about contain much more detailed information
> about the aerosol, but they are not part of the usual model output,
> even though that would be possible in principle. The reason why I have
> proposed my long list of variable names is twofold: 1) the CF
> convention contains a really well structured and well organized
> framework for variable naming (that alone would be reason enough); 2)
> I'd like to foster the use of those observations in the WMO GAW network
> that are so far underused for model comparisons.
>
> What has that to do with your proposed name for aerosol Mie scattering,
> especially since pure Mie scattering is a theoretical construct and
> therefore can't be measured? The syntax of the name you proposed
> originally,
> "volume_extinction_coefficient_in_air_due_to_mie_scattering_of_ambient_
> aerosol", would have conflicted with a whole other suite of names of
> measurable quantities I just proposed, which follow the syntax
> "volume_scattering_coefficient_in_air_due_to_dry_aerosol". This is why
> I proposed
> "volume_scattering_coefficient_in_air_due_to_ambient_aerosol_assuming_m
> ie_scattering" for your Mie scattering variable, where the syntax of
> both is in agreement.
>
> Was that helpful at all?
>
> Best regards,
> Markus
>
> _______________________________________
> Dr. Markus Fiebig
>
> Dept. Atmospheric and Climate Research (ATMOS)
> Norwegian Institute for Air Research (NILU)
> P.O. Box 100
> N-2027 Kjeller
> Norway
>
> Tel.: +47 6389-8235
> Fax : +47 6389-8050
> e-mail: Markus.Fiebig at nilu.no
> skype: markus.fiebig
>
> -----Original Message-----
> From: Shankar, Uma [mailto:ushankar at unc.edu]
> Sent: Freitag, 9. M?rz 2012 03:03
> To: X:m.schultz at fz-juelich.de; Markus Fiebig; cf-metadata at cgd.ucar.edu
> Subject: RE: warming up old stuff - part 1: aerosol mie scattering
>
> Hi Martin and Markus -
>
> At present CMAQ doesn't output extinction coefficients directly
> (although post processing can produce those outputs, but that is not a
> standard model application). However it's quite likely that the coupled
> WRF-CMAQ, due for public release in the near future, will have the full
> complement of aerosol optical properties in the output files. I will
> pass along to the responsible people at EPA. I agree with Markus that
> if the name represents measured as well as modeled quantities the name
> should be more universally applicable. I'm not sure that optical depth
> measurements give you the scattering coefficient though - I have seen
> extinction and absorption optical depths from which you would need to
> use a retrieval algorithm to get anything columnar or level-specific
> for the relevant coefficient. Would appreciate your feedback.
> Thanks -
> Uma
> ---------
> Uma Shankar, Research Associate
> Institute for the Environment
> Bank of America Plaza CB# 6116
> 137 E. Franklin St Room 644
> Chapel Hill NC 27599-6116
> Phone: (919) 966-2102
> Fax (919) 843-3113
> Mobile: (919) 441-9202
>
> In order that people may be happy in their work, these three things are
> needed: they must be fit for it; they must not do too much of it; and
> they must have a sense of success in it. -John Ruskin, author, art
> critic, and social reformer (1819-1900)
>
>
> -----Original Message-----
> From: Schultz, Martin [mailto:m.schultz at fz-juelich.de]
> Sent: Wednesday, March 07, 2012 5:16 AM
> To: Markus Fiebig; cf-metadata at cgd.ucar.edu
> Cc: Shankar, Uma
> Subject: RE: warming up old stuff - part 1: aerosol mie scattering
>
> Dear Markus,
>
> thanks for the thoughtful response. I cc this to Uma Shankar who
> had sent me the RSIG (http://badger.epa.gov/rsig/) CMAQ variable list
> from where this suggestion originated. CMAQ is of course a model. I
> don't think it would hurt to have also standard_names for pure model
> quantities, but I agree with you that one may have to phrase and define
> this more clearly. The name you propose is already in the list, and the
> suggestion was to include a more specific term to denote the specific
> contribution from Mie scattering.
>
> Best regards,
>
> Martin
>
> PS: original proposal was
> "* How can we get more specific about the "extinction coefficient"? In
> particular, we would like to express something like
> "..._due_to_Mie_scattering". But does this work with "
> volume_extinction_coefficient_in_air_due_to_ambient_aerosol". The new
> name would then become
> "volume_extinction_coefficient_in_air_due_to_Mie_scattering_of_ambient_
> aerosol" ? (and would "Mie" be spelled with "M" or "m"?)"
>
> > -----Original Message-----
> > From: Markus Fiebig [mailto:Markus.Fiebig at nilu.no]
> > Sent: Wednesday, March 07, 2012 9:31 AM
> > To: Schultz, Martin; cf-metadata at cgd.ucar.edu
> > Subject: RE: warming up old stuff - part 1: aerosol mie scattering
> >
> > Dear all,
> >
> > please excuse if I come in late into this discussion, but I would
> like
> > to make a few comments about the proposed variable name
> >
> >
> "volume_extinction_coefficient_in_air_due_to_mie_scattering_of_ambient
> > _aerosol"
> >
> > As it is written above, the name is self-contradicting. The aerosol
> > extinction coefficient is defined to include both, particle
> scattering
> > and absorption. The part of the aerosol extinction coefficient that
> is
> > due to particle scattering is commonly referred to as aerosol
> > scattering coefficient. Also, I need to apologise for not having
> > followed the discussion concerning the use of the term "mie", but it
> > appears rather to confuse than to clarify in the context here. Even
> > though the term Mie-particle is colloquially used for a spherical,
> > internally well mixed aerosol particle, such a particle exists only
> in
> > theory or in some numerical model. If the variable name is also to be
> used for an observed quantity, which I think it should, the term "Mie"
> should be avoided.
> >
> > How about putting this much simpler, and name the property:
> >
> > "volume_scattering_coefficient_in_air_due_to_ambient_aerosol"
> >
> > or, to avoid even more confusion:
> >
> > "volume_scattering_coefficient_at_stp_in_air_due_to_ambient_aerosol"
> >
> > Regards,
> > Markus
> >
> >
> >
> > _______________________________________
> > Dr. Markus Fiebig
> >
> > Dept. Atmospheric and Climate Research (ATMOS) Norwegian Institute
> for
> > Air Research (NILU) P.O. Box 100
> > N-2027 Kjeller
> > Norway
> >
> > Tel.: +47 6389-8235
> > Fax : +47 6389-8050
> > e-mail: Markus.Fiebig at nilu.no
> > skype: markus.fiebig
> >
>
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Received on Fri Mar 09 2012 - 18:55:25 GMT
