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Re: Simulation duration




Dear Ray and OCMIP modellers,

     Regarding the spin up criteria: It seems sensible if the criteria
for ending the spin up relates to the result of particular physical 
significance in the simulation, in the way that Jim's suggestion
of the air-sea flux of carbon does for the abiotic run.

   For the biotic run, perhaps we should have two criteria (not independent)
that the globally integrated air-sea flux should be less than (following
Jim's suggestion 0.01 Pg/yr) and that new production has reached some 
correspondingly small rate of change. 

   We often think of C-14 as an indicator of "age" of water masses. Perhaps
a criteria based on the mean ocean "age" (i.e. simple interpretation of
Del14C) would be appropriate. The criteria would be some critical value
of the volume weighted aging rate (years/year). Not sure what the critical
value ought to be yet though.

   
                              Mick            



On Mon, Feb 01, 1999 at 04:47:48PM -0500, Ray Najjar wrote:
> OCMIP modelers,
> 
> Jim and I would like to know from you what think are reasonable criteria for
> detemining when the abiotic and biotic simulations have reached equilibrium.
> 
> Jim has suggested that a globally integrated air-sea flux less than 0.01 Pg/yr
> indicates equilbrium for the abiotic DIC field.  Any thoughts on this and
> criteria for C-14 and the biotic run?
> 
> My inclination would be to do something like compute the time rate of change at
> each grid point, take the absolute value and compute the global average.  When
> this average is below some epsilon, you've reached equilibrium.
> 
> Ray

- -- 
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| Mick Follows                                                         | 
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