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Re: Small error in TA_ITER_1



OCMIPers,

The "small" error in the derivative term dfn/dx (in ta_iter_1.f) has been
corrected following the remarks by Christoph Voelker.  That routine is now
at version 1.2. Please use that latest version from now on.  As always you
can access that through the appropriate links on the Abiotic and Biotic
Web pages. 

As Christoph suggests, this error may be negligible.  If someone has
verified this, please respond!  Otherwise, modelers who have used
these routines should correspond to test if this small sign change is
completely negligible, or not.

On a related note, recall that I also sent a reminder in July stating that
these routines (co2calc.f, ta_iter_1.f, and drtsafe.f) are NOT optimized
for model runs.  Our experience at IPSL is that when used without any
modification, they are extremely costly. 

- -- Jim


On Tue, 10 Aug 1999, christoph voelker wrote:

> 
> There seems to be a small sign error in the calculation of
> the derivative of alkalinity with respect to H+ in TA_ITER_1;
> the term that comes from the alkalinity of the H+-ion has
> the wrong sign:
> 
> In fn everything is o.k.:
> 	fn = k1*x*dic/b +
> [snip]
>      &	     sit/(1.0 + x/ksi) -  <------ 
>      &	     x/c - [snip]
> 
> but in df = dfn/dx the term is wrong:
> 	df = ((k1*dic*b) - k1*x*dic*db)/b2 -
> [snip]
>      &	     sit/ksi/(1.0+x/ksi)**2. +  <------ 
>      &	     1.0/c + [snip]          
> 
> But since [h+] is of the order of 10^-5 mol/m^3, this probably
> makes no big difference.
> 
> Cheers, Christoph
> 
> **************************************************
> Christoph Voelker
> Dept. of Theoretical Oceanography
> Institut fuer Meereskunde an der Universitaet Kiel
> **************************************************
> 
> 

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