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<div>To whom it may concern,</div>
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<div>My name is Kaitlin Naughten and I have just started a postdoc at the British Antarctic Survey. <span style="font-size: 12pt;">I am setting up a Weddell Sea configuration of MITgcm, using an older configuration from a colleague as a starting point. The
old configuration used version c62r which I have now updated to c67, so I expect many options and "best practices" have changed between these versions.</span></div>
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<div><span style="font-size: 12pt;">Right now I'm trying to make sure I'm doing something sensible with mixing. GMRedi and KPP are switched on, and the relevant namelist parameters are as follows:</span></div>
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<div><span style="font-size: 12pt;">viscAr=1.E-4</span></div>
<div><span style="font-size: 12pt;">viscC2leith=3.0</span></div>
<div><span style="font-size: 12pt;">viscC2leithD=3.0</span></div>
<div><span style="font-size: 12pt;">diffKrT=1.E-4</span></div>
<div><span style="font-size: 12pt;">diffKrS=1.E-4</span></div>
<div><span style="font-size: 12pt;">cosPower=2.</span></div>
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<div><span style="font-size: 12pt;">From old messages here, it looks like my choices of mixing schemes are reasonable. But I am confused about whether cosPower is needed. </span><span style="font-size: 12pt;">ISOTROPIC_COS_SCALING is defined in GAD_OPTIONS.h,
but not in CPP_OPTIONS.h, so I understand cosPower only affects the tracers. But since GMRedi is on, is cosPower actually necessary and does it do anything? Furthermore, should I have cosPower scaling the momentum terms, or does the Leith parameterisation
already scale by grid size? I've looked at some old messages and at the code but I can't quite figure it out.</span></div>
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<div><span style="font-size: 12pt;">If it matters, the grid is polar spherical, quarter-degree scaled by cos of latitude, and I can see some eddy activity resolved. Later we plan to increase resolution.</span></div>
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<div><span style="font-size: 12pt;">Many thanks,</span></div>
<div><span style="font-size: 12pt;">Kaitlin Naughten</span></div>
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