Dear Jonathan,
Instead of 'moist' I would suggest 'ambient'. This would be consistent
with 'ambient' aerosol.
In addition, the mass fraction of water vapor in dry air is not zero,
this is possible and used in models.
I am not sure, if 'air' means dry_air to everybody, I would assume that
some take it as dry_air. Therefore I would suggest to always add dry or
ambient, also for the chemical constituents.
Best regards,
Christiane
Jonathan Gregory schrieb:
> Dear Alison et al.
>
> I wrote
>
>> I think we could include both of these:
>>
>>>> 'water_vapour_mixing_ratio'
>>>> 'mass_fraction_of_water_vapour_in_dry_air'
>> They are different quantities, and people should use the one which describes
>> their data.
>
> That was wrong, sorry, I wasn't thinking.
>
> Shouldn't the second option be
> mass_fraction_of_water_vapour_in_moist_air
> or just
> mass_fraction_of_water_vapour_in_air
> assuming that "air" means just as it comes i.e. not dry? The mass fraction
> of water vapour in dry air is zero. I think
> mass_fraction_of_water_vapour_in_[moist_]air
> water_vapour_mixing_ratio
> are two different quantities, which should have different standard names. If
> A is the mass of water vapour and B is the mass of dry air, the mixing ratio
> is A/B and the mass fraction is A/(A+B), I believe. I think the mass fraction
> is what we use for other chemical constituents. If C is the mass of some other
> species, the mass fraction of C in air is C/(A+B), because "air" would be
> assumed to be ambient, including whatever moisture A it has.
>
> Best wishes
>
> Jonathan
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--
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Christiane Textor
Laboratoire des Sciences du Climat et de l'Environnement
Unite Mixte de Recherche CEA-CNRS-UVSQ
LSCE/IPSL, CEA Saclay, Orme des Merisiers,
Bat. 701, Piece 3b, Point Courrier 129
F-91191 Gif-sur-Yvette Cedex
FRANCE
mailto: christiane.textor at lsce.ipsl.fr
Tel ++33 1 69 08 34 07 Fax ++33 1 69 08 77 16
GEOmon scientific coordinator http://www.geomon.eu
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Received on Thu Nov 06 2008 - 01:54:28 GMT
