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Dear MITgcm users,
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<div class="">I’m trying to close the point-wise heat/salt/tracer budget to machine precision in a regional model with RBCS, OBCS, KPP and EXF packages enabled. The model uses a linear free surface setup.</div>
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<div class="">To give an example, I have examined a local point that is away from the surface and the RBCS sponge region (1300m deep). My heat budget calculation is as following (where all the fluxes are diagnosed as daily average):</div>
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<div class="">The point is chosen at (i, j, k), and I start by calculating the local cell volume as: </div>
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<div class=""><span style="font-family: Menlo; font-size: 17px; font-variant-ligatures: no-common-ligatures;" class="">CellVol = RAC(i,j)
</span><span style="font-family: Menlo; font-size: 17px; font-variant-ligatures: no-common-ligatures; color: rgb(209, 113, 37);" class="">.*</span><span style="font-family: Menlo; font-size: 17px; font-variant-ligatures: no-common-ligatures;" class=""> DRF(k)
</span><span style="font-family: Menlo; font-size: 17px; font-variant-ligatures: no-common-ligatures; color: rgb(209, 113, 37);" class="">.*</span><span style="font-family: Menlo; font-size: 17px; font-variant-ligatures: no-common-ligatures;" class=""> hFacC(i,j,k)</span><span style="font-family: Menlo; font-size: 17px; font-variant-ligatures: no-common-ligatures; color: rgb(219, 39, 218);" class="">;</span></div>
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<div class="">The diffusion tendency is as following where the KPP non-local flux is also added at the end:</div>
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<span style="font-variant-ligatures: no-common-ligatures" class="">Dif_tend_TH = </span>
<span style="font-variant-ligatures: no-common-ligatures; color: #d17125" class="">-</span><span style="font-variant-ligatures: no-common-ligatures" class="">( (DFrE_TH(i,j,k)
</span><span style="font-variant-ligatures: no-common-ligatures; color: #d17125" class="">-</span><span style="font-variant-ligatures: no-common-ligatures" class=""> DFrE_TH(i,j,k</span><span style="font-variant-ligatures: no-common-ligatures; color: #d17125" class="">+</span><span style="font-variant-ligatures: no-common-ligatures; color: #ca3323" class="">1</span><span style="font-variant-ligatures: no-common-ligatures" class="">))</span><span style="font-variant-ligatures: no-common-ligatures; color: #d17125" class="">/</span><span style="font-variant-ligatures: no-common-ligatures" class="">CellVol
</span><span style="font-variant-ligatures: no-common-ligatures; color: #d17125" class="">+</span><span style="font-variant-ligatures: no-common-ligatures" class=""> (DFrI_TH(i,j,k)
</span><span style="font-variant-ligatures: no-common-ligatures; color: #d17125" class="">-</span><span style="font-variant-ligatures: no-common-ligatures" class=""> DFrI_TH(i,j,k</span><span style="font-variant-ligatures: no-common-ligatures; color: #d17125" class="">+</span><span style="font-variant-ligatures: no-common-ligatures; color: #ca3323" class="">1</span><span style="font-variant-ligatures: no-common-ligatures" class="">))</span><span style="font-variant-ligatures: no-common-ligatures; color: #d17125" class="">/</span><span style="font-variant-ligatures: no-common-ligatures" class="">CellVol
</span><span style="font-variant-ligatures: no-common-ligatures; color: #d17125" class="">+</span><span style="font-variant-ligatures: no-common-ligatures" class=""> (DFx_TH(i</span><span style="font-variant-ligatures: no-common-ligatures; color: #d17125" class="">+</span><span style="font-variant-ligatures: no-common-ligatures; color: #ca3323" class="">1</span><span style="font-variant-ligatures: no-common-ligatures" class="">,j,k)
</span><span style="font-variant-ligatures: no-common-ligatures; color: #d17125" class="">-</span><span style="font-variant-ligatures: no-common-ligatures" class=""> DFx_TH(i,j,k))</span><span style="font-variant-ligatures: no-common-ligatures; color: #d17125" class="">/</span><span style="font-variant-ligatures: no-common-ligatures" class="">CellVol
</span><span style="font-variant-ligatures: no-common-ligatures; color: #d17125" class="">+</span><span style="font-variant-ligatures: no-common-ligatures" class=""> (DFy_TH(i,j</span><span style="font-variant-ligatures: no-common-ligatures; color: #d17125" class="">+</span><span style="font-variant-ligatures: no-common-ligatures; color: #ca3323" class="">1</span><span style="font-variant-ligatures: no-common-ligatures" class="">,k)
</span><span style="font-variant-ligatures: no-common-ligatures; color: #d17125" class="">-</span><span style="font-variant-ligatures: no-common-ligatures" class=""> DFy_TH(i,j,k))</span><span style="font-variant-ligatures: no-common-ligatures; color: #d17125" class="">/</span><span style="font-variant-ligatures: no-common-ligatures" class="">CellVol
</span><span style="font-variant-ligatures: no-common-ligatures; color: #d17125" class="">+</span><span style="font-variant-ligatures: no-common-ligatures" class=""> (KPPr_TH(i,j,k)
</span><span style="font-variant-ligatures: no-common-ligatures; color: #d17125" class="">-</span><span style="font-variant-ligatures: no-common-ligatures" class=""> KPPr_TH(i,j,k</span><span style="font-variant-ligatures: no-common-ligatures; color: #d17125" class="">+</span><span style="font-variant-ligatures: no-common-ligatures; color: #ca3323" class="">1</span><span style="font-variant-ligatures: no-common-ligatures" class="">))</span><span style="font-variant-ligatures: no-common-ligatures; color: #d17125" class="">/</span><span style="font-variant-ligatures: no-common-ligatures" class="">CellVol
)</span><span style="font-variant-ligatures: no-common-ligatures; color: #db27da" class="">;</span></div>
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<div class="">Here is the advection tendency:</div>
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<span style="font-variant-ligatures: no-common-ligatures" class="">Adv_tend_TH = </span>
<span style="font-variant-ligatures: no-common-ligatures; color: #d17125" class="">-</span><span style="font-variant-ligatures: no-common-ligatures" class="">( (ADVr_TH(i,j,k)
</span><span style="font-variant-ligatures: no-common-ligatures; color: #d17125" class="">-</span><span style="font-variant-ligatures: no-common-ligatures" class=""> ADVr_TH(i,j,k</span><span style="font-variant-ligatures: no-common-ligatures; color: #d17125" class="">+</span><span style="font-variant-ligatures: no-common-ligatures; color: #ca3323" class="">1</span><span style="font-variant-ligatures: no-common-ligatures" class="">))</span><span style="font-variant-ligatures: no-common-ligatures; color: #d17125" class="">/</span><span style="font-variant-ligatures: no-common-ligatures" class="">CellVol
</span><span style="font-variant-ligatures: no-common-ligatures; color: #d17125" class="">+</span><span style="font-variant-ligatures: no-common-ligatures" class=""> (ADVx_TH(i</span><span style="font-variant-ligatures: no-common-ligatures; color: #d17125" class="">+</span><span style="font-variant-ligatures: no-common-ligatures; color: #ca3323" class="">1</span><span style="font-variant-ligatures: no-common-ligatures" class="">,j,k)
</span><span style="font-variant-ligatures: no-common-ligatures; color: #d17125" class="">-</span><span style="font-variant-ligatures: no-common-ligatures" class=""> ADVx_TH(i,j,k))</span><span style="font-variant-ligatures: no-common-ligatures; color: #d17125" class="">/</span><span style="font-variant-ligatures: no-common-ligatures" class="">CellVol
</span><span style="font-variant-ligatures: no-common-ligatures; color: #d17125" class="">+</span><span style="font-variant-ligatures: no-common-ligatures" class=""> (ADVy_TH(i,j</span><span style="font-variant-ligatures: no-common-ligatures; color: #d17125" class="">+</span><span style="font-variant-ligatures: no-common-ligatures; color: #ca3323" class="">1</span><span style="font-variant-ligatures: no-common-ligatures" class="">,k)
</span><span style="font-variant-ligatures: no-common-ligatures; color: #d17125" class="">-</span><span style="font-variant-ligatures: no-common-ligatures" class=""> ADVy_TH(i,j,k))</span><span style="font-variant-ligatures: no-common-ligatures; color: #d17125" class="">/</span><span style="font-variant-ligatures: no-common-ligatures" class="">CellVol
)</span><span style="font-variant-ligatures: no-common-ligatures; color: #db27da" class="">;</span></div>
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<span style="font-variant-ligatures: no-common-ligatures;" class="">The time tendency term is </span></div>
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<span style="font-variant-ligatures: no-common-ligatures;" class="">TOTTEND/86400 = 1.2712e-7 degC/s</span></div>
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<div style="margin: 0px; font-stretch: normal; line-height: normal;" class=""><span style="font-variant-ligatures: no-common-ligatures;" class="">And the sum of the advection and diffusion tendency is 1.2721e-7 degC/s, which is very close to the time tendency
term but not quite the same. The same issue also happens with my salt and passive tracer budgets. The diagnosed forcing terms (gT_Forc and gS_Forc) are zero around this point. I cannot think of any other contribution in the model.. I was wondering if anyone
has experienced this issue before? Thank you very much for your help!</span></div>
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<div style="margin: 0px; font-stretch: normal; line-height: normal;" class=""><span style="font-variant-ligatures: no-common-ligatures;" class="">Best,</span></div>
<div style="margin: 0px; font-stretch: normal; line-height: normal;" class="">Xiaozhou</div>
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