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<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Hi Martin,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Yes that’s right.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">The ‘buoyancyflux’ corresponds to the buoyancy flux at the ice-ocean interface so it can be calculated based on melt rate from the previous timestep. But I need to make sure I check the sign convention
that is used in SHELFICE package (depending on whether B>0 means melting or freezing L0 should be equal to ustar^3/(Kvon*B) or -ustar^3/(Kvon*B)).<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Assuming B<0 means freezing, then when B<0, etaStar would be set to 1.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">When B>0, if B</span><span style="font-family:Wingdings;mso-fareast-language:EN-US">à</span><span style="mso-fareast-language:EN-US">0+ (i.e. when melt-induced buoyancy production of TKE is negligible
compared with shear production of TKE, which is what is assumed in the current version of the code), then etaStar</span><span style="font-family:Wingdings;mso-fareast-language:EN-US">à</span><span style="mso-fareast-language:EN-US">1
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">I’ll give you an update once I have tested this.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Thank you<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Josephine<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span lang="EN-US">From:</span></b><span lang="EN-US"> MITgcm-support <mitgcm-support-bounces@mitgcm.org>
<b>On Behalf Of </b>Martin Losch<br>
<b>Sent:</b> 05 October 2022 15:57<br>
<b>To:</b> MITgcm Support <mitgcm-support@mitgcm.org><br>
<b>Subject:</b> Re: [MITgcm-support] SHELFICE Package: stability parameter<o:p></o:p></span></p>
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<p class="MsoNormal">Hi Josephine,<o:p></o:p></p>
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<p class="MsoNormal">do I get this right?<o:p></o:p></p>
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<p class="MsoNormal">etaStar = 1/ sqrt(1+zetaN*Kvon*buoyancyflux./(abs(f)*uStar**2*Rc))?<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">should go to zero for buoyancyFlux -> Inf, and to one for buoyanceFlux -> 0 (for positive buoyanceFlux), right?<o:p></o:p></p>
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<p class="MsoNormal">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.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Martin<o:p></o:p></p>
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<p class="MsoNormal">On 5. Oct 2022, at 14:13, Josephine Anselin - BAS <<a href="mailto:joslin53@bas.ac.uk">joslin53@bas.ac.uk</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Hi Martin,<o:p></o:p></p>
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<p class="MsoNormal"> <o:p></o:p></p>
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<p class="MsoNormal">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.<o:p></o:p></p>
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<p class="MsoNormal"> <o:p></o:p></p>
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<p class="MsoNormal">Thank you<o:p></o:p></p>
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<p class="MsoNormal">Josephine<span class="apple-converted-space"> </span><o:p></o:p></p>
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<p class="MsoNormal"> <o:p></o:p></p>
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<p class="MsoNormal"><b><span lang="EN-US">From:</span></b><span class="apple-converted-space"><span lang="EN-US"> </span></span><span lang="EN-US">MITgcm-support <<a href="mailto:mitgcm-support-bounces@mitgcm.org">mitgcm-support-bounces@mitgcm.org</a>><span class="apple-converted-space"> </span><b>On
Behalf Of<span class="apple-converted-space"> </span></b>Martin Losch<br>
<b>Sent:</b><span class="apple-converted-space"> </span>30 September 2022 08:50<br>
<b>To:</b><span class="apple-converted-space"> </span>MITgcm Support <<a href="mailto:mitgcm-support@mitgcm.org">mitgcm-support@mitgcm.org</a>><br>
<b>Subject:</b><span class="apple-converted-space"> </span>Re: [MITgcm-support] SHELFICE Package: stability parameter</span><o:p></o:p></p>
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<p class="MsoNormal"> <o:p></o:p></p>
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<p class="MsoNormal">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.<o:p></o:p></p>
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<p class="MsoNormal"> <o:p></o:p></p>
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<p class="MsoNormal">Martin<o:p></o:p></p>
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<p class="MsoNormal">On 29. Sep 2022, at 07:54, Martin Losch <<a href="mailto:Martin.Losch@awi.de">Martin.Losch@awi.de</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal"> <o:p></o:p></p>
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<p class="MsoNormal">Hi Josephine,<o:p></o:p></p>
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<p class="MsoNormal"> <o:p></o:p></p>
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<p class="MsoNormal">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).<o:p></o:p></p>
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<p class="MsoNormal"> <o:p></o:p></p>
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<p class="MsoNormal">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). <o:p></o:p></p>
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<p class="MsoNormal"> <o:p></o:p></p>
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<p class="MsoNormal">Martin<o:p></o:p></p>
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<p class="MsoNormal">On 28. Sep 2022, at 19:11, Josephine Anselin - BAS <<a href="mailto:joslin53@bas.ac.uk">joslin53@bas.ac.uk</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal"> <o:p></o:p></p>
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<p class="MsoNormal">Hi all,<o:p></o:p></p>
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<p class="MsoNormal"> <o:p></o:p></p>
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<p class="MsoNormal">In shelfice_thermodynamics.F (within the SHELFICE Package), the stability parameter (etastar) is set to 1.<o:p></o:p></p>
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<p class="MsoNormal"> <o:p></o:p></p>
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<p class="MsoNormal">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?<o:p></o:p></p>
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<p class="MsoNormal"> <o:p></o:p></p>
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<p class="MsoNormal">Many thanks,<o:p></o:p></p>
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<p class="MsoNormal" style="background:white;vertical-align:baseline"><span style="font-size:10.0pt;color:black;border:none windowtext 1.0pt;padding:0cm">_________________________________________</span><o:p></o:p></p>
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<p class="MsoNormal"><b><span lang="EN-US">Joséphine Anselin</span></b><o:p></o:p></p>
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<p class="MsoNormal"><i>Physical Oceanography PhD Student</i><o:p></o:p></p>
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<p class="MsoNormal"><span lang="EN-US">British Antarctic Survey, Polar Oceans Team</span><o:p></o:p></p>
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<p class="MsoNormal"><span lang="EN-US">University of Cambridge, Applied Mathematics</span><o:p></o:p></p>
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<p class="MsoNormal"> <o:p></o:p></p>
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