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<div class="">Dear fellow MITgcm-ers,</div>
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<div class="">I have a couple of questions about the implementation of the KPP scheme in the MITgcm code. I am interested in using the option of estimating reference values instead of using the surface values, because my model setup has a high vertical resolution.
There are a couple of things that have me puzzled in that part of the code:</div>
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<div class="">1) In general, the boundary layer depth is defined as the shallowest depth where the bulk Richardson number is equal to its critical value. Since we need the boundary layer depth to calculate the surface layer depth where MOST holds, I understand
that this provides a chicken-and-egg-type difficulty in practice. It looks like the boundary layer depth (hMix) in this case is set equal to the shallowest depth where dB/dz exceeds a hard-coded value of 5.2e-5 s^-2. </div>
<div class=""><span class="Apple-tab-span" style="white-space:pre"></span>1a) While this parameter value can be changed in the data.kpp file, I can’t find a reference to how this particular value was chosen. Was this based on literature, expert judgement, something
else?</div>
<div class=""><span class="Apple-tab-span" style="white-space:pre"></span>1b) Once the boundary layer depth using this threshold value is determined, this is what is used; in other words, it is not recalculated after the boundary layer depth has been estimated
based on the Richardson number criterion. Shouldn't it be? Or is the difference not large enough to warrant the additional computational expense?</div>
<div class=""><span class="Apple-tab-span" style="white-space:pre"></span>1c) Since the search for hMix starts at the bottom, wouldn’t this way of estimating the boundary layer depth potentially pose a problem in the presence of a bottom boundary layer? </div>
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<div class="">2) The comments in kpp_forcing_surf.F reiterate a few times that the current implementation does not handle cases where the surface layer depth exceeds the thickness of the first layer (i.e., high resolution). However, the statement that rules
out that option (z0(i,j) = MIN(zRef(i,j),drF(1)) is commented out, and so the IF statement in the calculation of uRef and vRef handles both high resolution and coarse resolution cases. Are the comments out of date, or am I missing something/interpreting this
incorrectly?</div>
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<div class="">Thanks for any input on this!</div>
<div class="">Renske</div>
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<span style="box-sizing: border-box; font-style: italic; line-height: inherit;" class=""><span style="box-sizing: border-box; font-weight: 700; line-height: inherit; color: rgb(0, 0, 0);" class="">Dr. Renske Gelderloos</span> (she/her)<br style="box-sizing: border-box;" class="">
Associate Research Scientist | Earth and Planetary Sciences<br style="box-sizing: border-box;" class="">
Krieger School of Arts & Sciences<br style="box-sizing: border-box;" class="">
Johns Hopkins University<br style="box-sizing: border-box;" class="">
Olin Hall 328, Baltimore, MD 21218<br style="box-sizing: border-box;" class="">
O: 410-516-5631</span></td>
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<span style="box-sizing: border-box; font-style: italic; line-height: inherit;" class="">This e-mail contains information that may be confidential. If you have received this in error, please notify me immediately and delete this e-mail.</span></td>
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