[MITgcm-support] Prescribing Constant 4°C Temperature in Idealized Lake Margins Throughout Simulation

[Fateme Sharifi]

Dear MITgcm Support Team,

I am currently working on an idealized model setup using MITgcm to
simulate *seasonal
ice-covered lakes*, with a focus on *moat formation*—ice-free lateral
regions that remain at approximately 4 °C throughout the running period.

In my setup, I represent an idealized freshwater lake with a *Gaussian-shaped
bathymetry*. The lake is initialized with a *vertically stratified
temperature profile*, ranging from 0 °C at the surface to 2 °C at the
bottom in the interior. To simulate moats, I initialize a lateral zone
along the lake boundary with a uniform temperature of *4 °C*, representing
maximum freshwater density.

My goal is to maintain this *lateral 4 °C moat temperature* fixed
throughout the simulation period, while allowing the interior to evolve
freely according to the model dynamics.

I would appreciate any guidance on the following:

   -

   Is there a way to *prescribe a constant temperature* (e.g., via a
   boundary condition or restoring term) in specific lateral grid cells (e.g.,
   within a ~500 m wide margin)?
   -

   Would you recommend using *sponge layers*, *restoring zones*, or another
   method for this purpose in the MITgcm framework?

Thank you in advance for your support.

Best regards,
Fatemeh Sadat Sharifi
Ph.D. Candidate at
The Leibniz Institute of Freshwater
 Ecology and Inland Fisheries (IGB)
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