This is essentially a CFL violation in the CICE model. You would need to reduce the timestep. In the CESM, the CICE timestep is tied to the coupling interval with the atmosphere. Have a look at ATM_NCPL and ICE_NCPL. Try doubling ATM_NCPL and this should help. For high resolution (0.1-degree) you can use xndt_dyn or ndtd depending on the version of the code. This allows you to take multiple dynamic timesteps per thermodynamic timestep.Dave
