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New CONTROL Run (Revised Abiotic HOWTO)



Dear OCMIP modelers,

A required "Control run" has been added to the new version of the Abiotic
HOWTO.  

WHY?
- ----
The control run is necessary because 3-D tracer fields and associated
fluxes in our Equilibrium run never reach perfect equilibrium. The
associated drift affects results for the transient runs. It may be
particularly important when comparing model differences over long time
periods. For example, a 200-yr transient integration that has an average
drift of only +0.01 Pg C/yr (i.e., the OCMIP's recommended limit) produces
a 2 Pg C error if there is no drift correction. Furthermore, some models
have larger drifts and drifts of opposite sign, making drift correction
even more important. A control run is necessary to drift-correct models,
before comparison.

To find out more, check out the new version of the Abiotic HOWTO
(see Abstract, and Sections 3-5). Note that 6 new routines have
been added for storing Control output.

Notes:
- ------
(1) In practice, the Control is easy to implement. Briefly, it is just
    like the Historical and Future runs, but with atm CO2 held at 278
    uatm.  There is very little extra programming.

(2) We must have your control output to be able to compare your
    transient Abiotic results (Historical, Future, Pulse, Injection)
    to those from other models.  Please submit your model output as 
    soon as possible (along with other Abiotic results). 

Thanks,

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                http://www.ipsl.jussieu.fr/~jomce
   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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