Dear MOM6 community,
I am running MOM6+SIS2 for the Indian Ocean regional model with a 1/4-degree resolution and 75 vertical hybrid (Hycom) layers. The model is forced with climatological wind, heat and freshwater fluxes. The WOA13 Temperature and Salinity climatology is provided as open boundary conditions for the eastern and southern boundary of the Indian Ocean domain. And the other fields, such as U, V, and eta, are provided as zero at the boundary. The boundary condition is specified in the MOM_input as shown below:
OBC_NUMBER_OF_SEGMENTS = 2
OBC_FREESLIP_VORTICITY = False
OBC_COMPUTED_VORTICITY = True
OBC_FREESLIP_STRAIN = False
OBC_COMPUTED_STRAIN = True
OBC_ZERO_BIHARMONIC = True
OBC_RAMP_TIMESCALE = 2.0
OBC_SEGMENT_001 = "J=0,I=0:N,FLATHER,ORLANSKI,NUDGED,ORLANSKI_TAN,NUDGED_TAN" !
OBC_SEGMENT_001_VELOCITY_NUDGING_TIMESCALES = 0.3, 360.0
OBC_SEGMENT_002 = "I=N,J=0:N,FLATHER,ORLANSKI,NUDGED,ORLANSKI_TAN,NUDGED_TAN" !
OBC_SEGMENT_002_VELOCITY_NUDGING_TIMESCALES = 0.3, 360.0
I'm writing to confirm my understanding of how this open boundary condition works. In the above setup, even though I'm providing zero velocities, I observed non zero velocities at the boundaries in model simulations. I guess these non-zero velocities are the geostrophic velocity computed from the WOA Temperature and Salinity climatology provided at the boundary and the same are used for nudging. Is this how it works? Please correct me if I'm missing something.
I am running MOM6+SIS2 for the Indian Ocean regional model with a 1/4-degree resolution and 75 vertical hybrid (Hycom) layers. The model is forced with climatological wind, heat and freshwater fluxes. The WOA13 Temperature and Salinity climatology is provided as open boundary conditions for the eastern and southern boundary of the Indian Ocean domain. And the other fields, such as U, V, and eta, are provided as zero at the boundary. The boundary condition is specified in the MOM_input as shown below:
OBC_NUMBER_OF_SEGMENTS = 2
OBC_FREESLIP_VORTICITY = False
OBC_COMPUTED_VORTICITY = True
OBC_FREESLIP_STRAIN = False
OBC_COMPUTED_STRAIN = True
OBC_ZERO_BIHARMONIC = True
OBC_RAMP_TIMESCALE = 2.0
OBC_SEGMENT_001 = "J=0,I=0:N,FLATHER,ORLANSKI,NUDGED,ORLANSKI_TAN,NUDGED_TAN" !
OBC_SEGMENT_001_VELOCITY_NUDGING_TIMESCALES = 0.3, 360.0
OBC_SEGMENT_002 = "I=N,J=0:N,FLATHER,ORLANSKI,NUDGED,ORLANSKI_TAN,NUDGED_TAN" !
OBC_SEGMENT_002_VELOCITY_NUDGING_TIMESCALES = 0.3, 360.0
I'm writing to confirm my understanding of how this open boundary condition works. In the above setup, even though I'm providing zero velocities, I observed non zero velocities at the boundaries in model simulations. I guess these non-zero velocities are the geostrophic velocity computed from the WOA Temperature and Salinity climatology provided at the boundary and the same are used for nudging. Is this how it works? Please correct me if I'm missing something.