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Re: Today's new Abiotic HOWTO (final) - 2. New IPCC run



OCMIP modelers,

Depending on one's point of view, perhaps the most important change in
the latest Abiotic HOWTO (Revision 1.14), released today, is that it now
includes the new scenario requested by the IPCC (see Corinne Le
Quere's recent e-mail to ocmip-all on this subject).

I have labeled this scenario "CIS92A". Like other runs, CIS92A
specifies atmospheric CO2 concentrations with which we will force our
models.  Many models of the terrestrial biosphere have already been
forced with this CIS92A scenario, hence the IPCC's interest in having
us make this run.  The actual concentrations in this file derive from
a simplified forward run driven by carbon emissions (from IPCC
emissions scenario IS92a).  The simplified run comes from Wigley. He
apparently used an old Green's function, from Maier-Reimer and
Hasselmann (1987), to compute oceanic uptake; I'm not sure what was
done to compute uptake by the terrestrial biosphere.  In any case, our
interest here is not these details, but the commonality needed for
IPCC comparison of both ocean and terrestrial reservoirs of
anthropogenic carbon.

I have taken the liberty to replace our previously planned future run
S450 with CIS92A.  Of both previously planned future runs (S450 and
S650), S450 appears the most unrealistic.  Furthermore, future run
CIS92A is shorter, ending in 2100.0 instead of 2300.0.  Thus groups
should be able to complete CIS92a very soon--remember that the related
OCMIP-2 deadlines have essentially arrived already.  Furthermore, as
Corinne mentioned, the IPCC needs these CIS92A results by the end of
December 1999; those who contribute will be acknowledged as
contributing authors on the IPCC report. For OCMIP-2 we need your
output from future run S650 as well as from future run CIS92A.

- -- Jim


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   James Orr                      
   Laboratoire des Sciences du Climat et de l'Environnement
   Unite Mixte de Recherche CEA-CNRS

   LSCE, CEA Saclay                
   Bat. 709 - Orme                 mailto:  orr@cea.fr
   F-91191 Gif-sur-Yvette Cedex    Phone:   (33) (0)1 69 08 77 23
   FRANCE                          Fax:     (33) (0)1 69 08 77 16
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