Hi,
I am runing a extreme high simulation with 20 m (a one-way nesting from 7.5 km 1.5 km 500 m 100 m down to 20 m) reoslution and NBQ turning on. However, I have tried a number of tests, but it always blows up with noise growing in the deep layers. Please see the figure below. Does someone have any idea what the problem is? The details of the configuration is also shown below. Some other information may be helpful:
(1) The model runs safely with 3s time step if I just turn NBQ off.
(2) Time steps I have used: 0.1s and 0.3s. All failed with the same problem.
Here is a figure of u in the deep layers (very close the bottom, 150 layers in 5000 m water depth)
REGIONAL
KuroSI
MPI
NBQ
DIAG_CFL
OBC_EAST
OBC_WEST
OBC_NORTH
OBC_SOUTH
W_HADV_TVD
W_VADV_TVD
GLS_MIX2017_3D
CURVGRID
SPHERICAL
MASKING
NEW_S_COORD
SOLVE3D
UV_COR
UV_ADV
SALINITY
NONLIN_EOS
SPLIT_EOS
UV_HADV_TVD
UV_VIS2
UV_VIS_SMAGO
UV_MIX_S
UV_VADV_TVD
TS_HADV_WENO5
TS_DIF2
TS_MIX_ISO
TS_VADV_WENO5
SPONGE
GLS_MIXING
GLS_KEPSILON
CANUTO_A
ANA_DIURNAL_SW
QCORRECTION
SFLX_CORR
FRC_BRY
Z_FRC_BRY
M2_FRC_BRY
M3_FRC_BRY
T_FRC_BRY
OBC_NBQ
OBC_M3ORLANSKI
OBC_TORLANSKI
ANA_BSFLUX
ANA_BTFLUX
OBC_M2CHARACT
M2FILTER_NONE
TRACERS
TEMPERATURE
M3FAST
NBQ_IMP
HZR
NBQ_PERF
NBQ_GRID_SLOW
NBQ_HZCORRECT
OBC_NBQORLANSKI
OBC_WORLANSKI
VAR_RHO_2D
VIS_COEF_3D
TS_MIX_IMP
TS_MIX_ISO_FILT
NTRA_T3DMIX
SPONGE_GRID
SPONGE_DIF2
SPONGE_VIS2
NF_CLOBBER