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Re: minor corrections, a plea for consistency
- Subject: Re: minor corrections, a plea for consistency
- From: firstname.lastname@example.org (Ken Caldeira)
- Date: Wed, 24 Jun 1998 10:18:56 -0700
Does it make sense to include air pressure variation for some tracers and
not for others? Why not be consistent: decide what factors to consider, and
then consider those factors for all tracers. If I am going to put something
in my code to computer surface pressures using total atmospheric pressure,
why should I add a branch that says "don't do this for cfc's"?
P.S. I know this won't make any real difference, so don't let me block a
>I would agree that sea level atmospheric pressure need not be included in
>the CFC protocols, but for additional reasons.
>Your arguments seem appropriate for the vertical perspective for "natural"
>tracers. Supplemental reasons can be given when considering horizontal
>variability. Horizontal temperature variation has a much larger effect on
>the gas transfer coefficient for CFC's than for CO2. For CO2, the
>temperature variation in the gas transfer coefficient's solubility and
>Schmidt number terms almost cancel one another out; such is not so for
>CFC's. Variability in CFC concentrations is much larger due to changes in
>temperature T than due to changes in atmospheric pressure P at sea level.
>For CFC's, modelers need to take into account temperature driven
>variability but can live with a 3% error due to changes in P.
>Furthermore, one must consider anthropogenic tracers. In a 1-D vertical
>sense, the dynamic range for CFC's is much larger than for anthropogenic
>CO2 and post-nuclear C-14 simply because measurements can be made with
>much greater precision, not because of a relatively greater recent
>increase in the atmosphere. So vertical reasoning won't work here;
>however, horizontal arguments given above still seem appropriate.
> James Orr Laboratoire des Sciences du Climat
> LSCE, CEA Saclay et de l'Environnement
> Bat. 709 - Orme Unite Mixte de Recherche CEA-CNRS
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