[MITgcm-support] Grid-scale noise in a nested simulation with EXF

[Ruan Xiaozhou]

Dear MITgcm users,

I’m running a hydrostatic regional simulation with all obcs, rbcs and exf (JRA55) packages enabled. As I was looking through the output of the temperature field, there was grid-scale noise appearing near the surface (top 3 levels) right after the simulation began. The noise seems to be related to very strong convective events at the surface (it’s gone when I turn off the EXF package). The top layer becomes unstable with super strong cooling which could not be improved with the convective adjustment (e.g. ivdc_kappa). When I diagnosed the EXF variables, similar noise pattern can be found in the sensible heat flux as well. I was wondering if anyone has seen this before? I have checked that all the input files have the correct precision. Any suggestions would be appreciated. Many thanks for your time!

Best,
Xiaozhou