[MITgcm-support] SHELFICE Package: stability parameter

[Martin Losch]

Hi Josephine,

do I get this right?
etaStar = 1/ sqrt(1+zetaN*Kvon*buoyancyflux./(abs(f)*uStar**2*Rc))?

should go to zero for buoyancyFlux -> Inf, and to one for buoyanceFlux -> 0 (for positive buoyanceFlux), right?
That should work. Let me know if this works for you and maybe you can even add it to the code, once you are confident that it works.

Martin

> On 5. Oct 2022, at 14:13, Josephine Anselin - BAS <joslin53 at bas.ac.uk> wrote:
> 
> Hi Martin,
>  
> Thank you very much for your reply. I will try to implement the formula using Lo=ustar^3 / (Kvon * buoyancyflux) and check if the jump that you pointed out causes an issue.
>  
> Thank you
> Josephine 
>  
> From: MITgcm-support <mitgcm-support-bounces at mitgcm.org> On Behalf Of Martin Losch
> Sent: 30 September 2022 08:50
> To: MITgcm Support <mitgcm-support at mitgcm.org>
> Subject: Re: [MITgcm-support] SHELFICE Package: stability parameter
>  
> Note that said equation 18 is not defined for Lo<0 for which etaStar should be set to 1, but the formula goes to 0 for Lo -> 0, so that there will be jump/discontinuity at Lo = 0 (from 0 to 1). This may be one of the reasons (appart from the unclear Lo), why this formula was never implemented.
>  
> Martin
> 
> 
> On 29. Sep 2022, at 07:54, Martin Losch <Martin.Losch at awi.de <mailto:Martin.Losch at awi.de>> wrote:
>  
> Hi Josephine,
>  
> I am not aware of any attemps, but there’s a code sketch that is commented out (see around lines 482-484 in shelfice_thermodynamics.F).
>  
> The H+J99 paper does not describe, how to evaluate the Obukhov length Lo, but otherwise is should be straightforward to implement this (f=fCori(i,j,bi,bj), Rc=0.2, zetaN=0.052 according to table1 in H+J99). 
>  
> Martin
> 
> 
> On 28. Sep 2022, at 19:11, Josephine Anselin - BAS <joslin53 at bas.ac.uk <mailto:joslin53 at bas.ac.uk>> wrote:
>  
> Hi all,
>  
> In shelfice_thermodynamics.F (within the SHELFICE Package), the stability parameter (etastar) is set to 1.
>  
> Has anyone tried to modify the code to compute the stability parameter as per Equation 18 in Holland & Jenkins (1999). If yes, is the modified version available online?
>  
> Many thanks,
> _________________________________________
> Joséphine Anselin
> Physical Oceanography PhD Student
> British Antarctic Survey, Polar Oceans Team
> University of Cambridge, Applied Mathematics
>  
> 
> 
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