[MITgcm-support] Problem: Extreme Tidal Currents in the Simulation at Narrow Channels.

[Martin Losch]

Hi there,

I think you didn’t get any replies so far because your problem description provides little detail except that you get higher currents than expected. We do not know anything about the boundary conditions (the most likely source of too high currents), the model domain, grid spacing, parameters (except for the few that you now provided in the second email). I don’t know how to help without a comprehensive description of your simulation. I.e. one would need at least your namelist files (all contained the stdout of the model) and your options-files (normally in the code directory) to give any advice.

Martin

> On 14. May 2024, at 15:32, Killampalli Rajesh <rajesh70530 at gmail.com> wrote:
> 
> Dear MITgcm community
> 
> I have added additional points to the earlier post "Extreme tidal currents in the simulation at narrow channels".Model mesh resolution is 100 metres. I'm attempting to resolve this issue by adjusting the bottomdragliner coefficient, which was previously set to 0.002. When it increases to 0.006, the model blows up and writes NaNs. For 0.005, the model may run, but the velocities are not reduced as expected, and less variance is recognised. Currently, the maximum channel flow was 1.25m/s; after modifying to 0.005, it was 1.21m/s redused. and I experimented with ViscAh from 10 to 100, but no substantial difference was seen. Can someone advise how to solve this?          
> 
> Best Regards
> Killampalli Rajesh
> 
> On Wed, May 8, 2024 at 6:56 PM Killampalli Rajesh <rajesh70530 at gmail.com <mailto:rajesh70530 at gmail.com>> wrote:
>> Dear MITgcm community 
>> 
>> Thank you for your assistance; I'm modelling tidal circulation in the lagoon, which is connected to the coastal seas.The research region includes lagoon and coastal waterways. The boundary conditions include baroclinic tidal currents at open boundaries in data.obcs, OBEam, and OBEph only on the eastern border, and OBCS_Tides specified in the model. The model results is verified using tidal heights with the tide gauge data, however the tidal currents are exaggerated. In example, the model findings suggest extremely strong tidal currents at the mouth/channel, which contradicts reality.
>> 
>> Best Regards
>> Killampalli Rajesh
>> 
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