Dear Martin

OK. Thanks for explaining and sorry I didn't notice the correct point. I am
happy then.

Best wishes

Jonathan

On Thu, May 09, 2019 at 12:26:40PM +0000, Martin Juckes - UKRI STFC wrote:
> Date: Thu, 9 May 2019 12:26:40 +0000
> From: Martin Juckes - UKRI STFC <martin.juc...@stfc.ac.uk>
> To: Jonathan Gregory <j.m.greg...@reading.ac.uk>,
>  "cf-metadata@cgd.ucar.edu" <cf-metadata@cgd.ucar.edu>
> Subject: Re: [CF-metadata] Some standard name updates to improve
>  consistency.
> 
> Dear Jonathan,
> 
> 
> On the question of the use of the phrase "ambient_aerosol" when referring to 
> the aerosol itself, rather than to the particles within the aerosol, I fear 
> that my comment which you quote may have become detached from the intended 
> context.
> 
> 
> I am happy with the distinction between "aerosol" (the suspension of particle 
> in air) and "aerosol_particles" (the particles which are suspended). My 
> comment to Alison referred to the use of the qualifier "ambient" when talking 
> about the aerosol itself: is it necessary or useful?
> 
> 
> The issue cam up because there are 5 standard names using the phrase 
> "dust_ambient_aerosol_particles_direct_radiative_effect" which I suggested 
> changing to "dust_aerosol_direct_radiative_effect". This would be consistent 
> with the usage in the literature, which would, I believe, make the terms 
> easier to read. In this case, there is nothing wrong with referring to the 
> aerosol suspension. Alison agreed with these points, but would like to retain 
> "ambient", as in "dust_ambient_aerosol_direct_radiative_effect". When talking 
> about particles within an aerosol it is very important to distinguish between 
> measurements representative of their state in the atmospheric suspension vs. 
> the state they might be in after sampling. "ambient", when qualifying 
> "aerosol_particles", means that we are describing the particles as they exist 
> in the aerosol. As a qualification of "aerosol" I can't see that it has any 
> meaning.
> 
> 
> The 4 terms which you refer to using "aerosol" rather than 
> "aerosol_particles" are ones which Alison agreed to change to include 
> "particles" earlier in this thread. These are all terms which are clearly 
> intended to refer only to the particles.
> 
> 
> regards,
> 
> Martin
> 
> 
> ________________________________
> From: CF-metadata <cf-metadata-boun...@cgd.ucar.edu> on behalf of Jonathan 
> Gregory <j.m.greg...@reading.ac.uk>
> Sent: 07 May 2019 18:19
> To: cf-metadata@cgd.ucar.edu
> Subject: Re: [CF-metadata] Some standard name updates to improve consistency.
> 
> Dear Martin and Alison
> 
> Thank you for carefully pursuing this detailed discussion. The degree of
> consistency which Martin remarked upon initially is encouraging, but it's also
> evident that we have to work very hard to achieve that, and any tools that we
> can put in place to make it easier (as Martin is thinking about, I believe)
> are well worth considering.
> 
> I have some small points.
> 
> >   1.  I've looked into the elemental/black carbon issue briefly
> ...
> > it may make sense to deal with that in a separate discussion and try to get 
> > some relevant experts involved.
> 
> I agree with that conclusion.
> 
> > 9. I'm still a little uncomfortable with the idea of "ambient_aerosol" 
> > referring to the suspension of particles in air. The phrase 
> > "ambient_aerosol_particles" is used when we are referring to properties of 
> > the particles rather than the suspension
> 
> This is like the distinction between ocean vs sea_water and atmosphere vs air.
> 
> > I can't think of a meaningful interpretation of a "dry aerosol" (I think 
> > dust_dry_aerosol is only used in the form dust_dry_aerosol_particles).
> 
> We have the following names which mention dry_aerosol without particles:
> 
> mass_concentration_of_biomass_burning_dry_aerosol_in_air
> mass_fraction_of_mercury_dry_aerosol_in_air
> tendency_of_atmosphere_mass_content_of_mercury_dry_aerosol_due_to_emission
> tendency_of_atmosphere_mass_content_of_sulfate_dry_aerosol_expressed_as_sulfur_due_to_wet_deposition
> 
> > For "relative_humidity_for_aerosol_particle_size_selection", I recognise 
> > that this would be the only use of "particle" in the singular.
> 
> This is a minor concern, but to avoid introducing it in the singular we could
> write relative_humidity_for_size_selection_of_aerosol_particles - that might
> be easier to read as well.
> 
> > I suggest we add 'A positive radiative forcing or radiative effect is
> equivalent to a downward radiative flux and contributes to a warming of the
> earth system.'
> 
> I agree that for the sake of clarity it would be good to add this. It's
> consistent with literature, as you say, and also with the IPCC AR5 glossary,
> which says, "Radiative forcing is the change in the net, downward minus 
> upward,
> radiative flux ...".
> 
> Best wishes
> 
> Jonathan
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