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<span style="font-family:Times New Roman;font-size:13px;">Dear MITgcm Support Team,</span>
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<span style="font-family:Times New Roman;font-size:13px;">I hope this message finds you well.</span><span style="font-family:Times New Roman;"> <span style="font-size:14px;"></span><br>
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<span style="font-family:Times New Roman;"><span style="font-family:Times New Roman;font-size:13px;">I am currently working on a simulation project using the MITgcm to study the dynamics of a lake, including the freezing process during winter. I have encountered some confusion regarding the behavior of the model with respect to the parameters </span><strong><span style="font-family:Times New Roman;font-size:13px;">deltaTtracer</span></strong><span style="font-family:Times New Roman;font-size:13px;">, </span><strong><span style="font-family:Times New Roman;font-size:13px;">deltaTmom</span></strong><span style="font-family:Times New Roman;font-size:13px;">, and </span><strong><span style="font-family:Times New Roman;font-size:13px;">deltaT</span></strong><strong><span style="font-family:Times New Roman;font-size:13px;">Clock</span></strong><span style="font-family:Times New Roman;font-size:13px;">, and I am seeking your guidance.</span></span>
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<span style="font-family:Times New Roman;font-size:13px;">In my understanding, the model should operate as follows when given the settings:</span>
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<span style="font-family:Times New Roman;font-size:13px;">deltaTClock = 3600s</span>
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<span style="font-family:Times New Roman;font-size:13px;">deltaTtracer = 1800s</span>
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<span style="font-family:Times New Roman;font-size:13px;">deltaTmom = 100s</span>
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<span style="font-family:Times New Roman;font-size:13px;">I believed that over one deltaTClock period, the tracer equations would be updated twice, and the momentum equations would be updated 36 times.</span>
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<span style="font-family:Times New Roman;font-size:13px;"><br>
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<span style="font-family:Times New Roman;font-size:13px;">However, I have conducted two different simulations with the following configurations and results:</span>
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<span style="font-family:Times New Roman;font-size:13px;">First simulation configuration:</span>
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<span style="font-family:Times New Roman;font-size:13px;">nIter0 = 0</span>
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<span style="font-family:Times New Roman;font-size:13px;">nTimeSteps = 13199</span>
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<span style="font-family:Times New Roman;font-size:13px;">deltaTClock = 3600s</span>
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<span style="font-family:Times New Roman;font-size:13px;">deltaTmom = 0.00001s</span>
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<span style="font-family:Times New Roman;font-size:13px;">deltaTtracer = 3600s</span>
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<strong><span style="font-family:Times New Roman;font-size:13px;"><span style="font-size:13px;">The resu</span><span style="font-size:13px;">lting ice_iceH output seemed more reasonable, with ice formation as expected.</span></span></strong>
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<span style="font-family:Times New Roman;font-size:13px;">Second simulation configuration:</span>
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<span style="font-family:Times New Roman;font-size:13px;">nIter0 = 0</span>
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<span style="font-family:Times New Roman;font-size:13px;">nTimeSteps = 13199</span>
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<span style="font-family:Times New Roman;font-size:13px;">deltaTClock = 3600s</span>
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<span style="font-family:Times New Roman;font-size:13px;">deltaTmom = 0.001s</span>
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<span style="font-family:Times New Roman;font-size:13px;">deltaTtracer = 1s</span>
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<strong><span style="font-family:Times New Roman;"><span style="font-size:13px;"><span style="font-size:13px;">Surprisingly, this simulation di</span><span style="font-size:13px;">d not produce any ice formation</span></span><span style="font-size:13px;">.</span></span></strong>
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<span style="font-family:Times New Roman;"><span style="font-size:13px;">The driving data spans from 2015-06-15 to 2016-12-15 with a time resolution of 3600 seconds. </span><span style="font-size:13px;">Intuitively, I think that the si</span><span style="font-size:13px;">mulation resul</span><span style="font-size:13px;">ts s</span><span style="font-size:13px;"><span style="font-size:13px;">hould be the same for both configurations </span><span style="font-size:13px;">, with only a difference in runtime</span><span style="font-size:13px;">. </span></span><span style="font-size:13px;">I am puzzled by the behavior of these parameters, particularly deltaTtracer and deltaTmom, and how they actually take effect within the model.</span></span>
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<span style="font-family:Times New Roman;"><br>
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<span style="font-family:Times New Roman;"><span style="font-size:13px;">Could you please clarify how these parameters are supposed to function within the model, and whether my understanding aligns with the model's implementation? </span><br>
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<span style="font-family:Times New Roman;font-size:13px;">I would greatly appreciate
any suggestions or guidance you could provide. I am really looking forward to your valuable insights and suggestions.</span>
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<span style="font-family:Times New Roman;"><br>
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<span style="font-family:Times New Roman;font-size:13px;">Best regards,</span> <span style="font-family:Times New Roman;"><br>
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<span style="font-family:Times New Roman;"><br>
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<span style="font-family:Times New Roman;font-size:13px;">Hong Tang</span>
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<span style="font-family:Times New Roman;font-size:13px;">University of Chinese Academy of Chinese</span><br>
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