Daily wind cycling error in MOM6 ocean-only idealized model
Opened this issue · 3 comments
Hi! I want to set wind stress with 3 months of variability as input data in the MOM6 ocean-only idealized model, but I found it is constant without varying... could anyone help me with this issue? Thanks!
The tau_mag output (show as constant):
My input data showed below:
Also, my configuration setting:
! Surface forcing
BUOY_CONFIG = "zero" ! read buoyancy forcing from the file
WIND_CONFIG = "file" ! read wind forcing from the file
WIND_FILE = "wind.nc" ! the file in which the wind stresses are found
WINDSTRESS_X_VAR = "STRESS_X" ! the name of the x-wind stress variable in WIND_FILE
WINDSTRESS_Y_VAR = "STRESS_Y" ! the name of the y-wind stress variable in WIND_FILE
WIND_STAGGER = "A" ! how the wind stress components are staggered in WIND_FILE
RESTOREBUOY = False ! the buoyancy fluxes drive the model back toward some specified surface state
! with a rate given by FLUXCONST
DT_FORCING = 86400 ! s-1, time step for changing forcing (1 day)
Recent finding: The input data could only be read with 365 days, less or more days will make the MOM6 ocean-only model read wind stress as a constant defaultly. To derive wind stress variability with 3 months effect, I chose to save model output every 360 days, then it worked well.
For reasons I will not defend, the netcdf data needs certain attributes (not standard). I'm not sure where the documentation is (somewhere on the FMS pages) but an example of a file that does work is in ocean_only/global. Here's the top ncdump -h of that file. Try adding the calender, calendar_type and cartesian_axis to the coordinate variables (esp. time).
netcdf ocean_forcing_daily {
dimensions:
xh = 360 ;
yh = 210 ;
time = UNLIMITED ; // (365 currently)
nv = 2 ;
xq = 360 ;
yq = 210 ;
variables:
double xh(xh) ;
xh:long_name = "h point nominal longitude" ;
xh:units = "degrees_E" ;
xh:cartesian_axis = "X" ;
double yh(yh) ;
yh:long_name = "h point nominal latitude" ;
yh:units = "degrees_N" ;
yh:cartesian_axis = "Y" ;
double time(time) ;
time:long_name = "time" ;
time:units = "days since 0001-01-01 00:00:00" ;
time:cartesian_axis = "T" ;
time:calendar_type = "NOLEAP" ;
time:calendar = "NOLEAP" ;
time:bounds = "time_bounds" ;
double nv(nv) ;
nv:long_name = "vertex number" ;
nv:units = "none" ;
nv:cartesian_axis = "N" ;
double xq(xq) ;
xq:long_name = "q point nominal longitude" ;
xq:units = "degrees_E" ;
xq:cartesian_axis = "X" ;
double yq(yq) ;
yq:long_name = "q point nominal latitude" ;
yq:units = "degrees_N" ;
yq:cartesian_axis = "Y" ;
float SW(time, yh, xh) ;
SW:long_name = "Shortwave radiation flux into ocean" ;
SW:units = "Watt meter-2" ;
SW:missing_value = 1.e+20f ;
SW:_FillValue = 1.e+20f ;
SW:cell_methods = "time: mean" ;
SW:time_avg_info = "average_T1,average_T2,average_DT" ;
SW:standard_name = "surface_net_downward_shortwave_flux" ;
float LW(time, yh, xh) ;
LW:long_name = "Longwave radiation flux into ocean" ;
LW:units = "Watt meter-2" ;
LW:missing_value = 1.e+20f ;
LW:_FillValue = 1.e+20f ;
LW:cell_methods = "time: mean" ;
LW:time_avg_info = "average_T1,average_T2,average_DT" ;
LW:standard_name = "surface_net_downward_longwave_flux" ;
float latent(time, yh, xh) ;
latent:long_name = "Latent heat flux into ocean due to fusion and evaporation" ;
latent:units = "Watt meter-2" ;
latent:missing_value = 1.e+20f ;
latent:_FillValue = 1.e+20f ;
latent:cell_methods = "time: mean" ;
latent:time_avg_info = "average_T1,average_T2,average_DT" ;
float sensible(time, yh, xh) ;
sensible:long_name = "Sensible heat flux into ocean" ;
sensible:units = "Watt meter-2" ;
sensible:missing_value = 1.e+20f ;
sensible:_FillValue = 1.e+20f ;
sensible:cell_methods = "time: mean" ;
sensible:time_avg_info = "average_T1,average_T2,average_DT" ;
sensible:standard_name = "surface_downward_sensible_heat_flux" ;
float evap(time, yh, xh) ;
evap:long_name = "Evaporation at ocean surface (usually negative)" ;
evap:units = "kilogram meter-2 second-1" ;
evap:missing_value = 1.e+20f ;
evap:_FillValue = 1.e+20f ;
evap:cell_methods = "time: mean" ;
evap:time_avg_info = "average_T1,average_T2,average_DT" ;
float taux(time, yh, xq) ;
taux:long_name = "Zonal Wind Stress" ;
taux:units = "Pascal" ;
taux:missing_value = 1.e+20f ;
taux:_FillValue = 1.e+20f ;
taux:cell_methods = "time: mean" ;
taux:time_avg_info = "average_T1,average_T2,average_DT" ;
taux:standard_name = "surface_downward_x_stress" ;
float tauy(time, yq, xh) ;
tauy:long_name = "Meridional Wind Stress" ;
tauy:units = "Pascal" ;
tauy:missing_value = 1.e+20f ;
tauy:_FillValue = 1.e+20f ;
tauy:cell_methods = "time: mean" ;
tauy:time_avg_info = "average_T1,average_T2,average_DT" ;
tauy:standard_name = "surface_downward_y_stress" ;
float ustar(time, yh, xh) ;
ustar:long_name = "Surface friction velocity" ;
ustar:units = "meter second-1" ;
ustar:missing_value = 1.e+20f ;
ustar:_FillValue = 1.e+20f ;
ustar:cell_methods = "time: mean" ;
ustar:time_avg_info = "average_T1,average_T2,average_DT" ;
float SST(time, yh, xh) ;
SST:long_name = "Sea Surface Temperature" ;
SST:units = "Celsius" ;
SST:missing_value = -1.e+34f ;
SST:_FillValue = -1.e+34f ;
SST:cell_methods = "time: mean" ;
SST:time_avg_info = "average_T1,average_T2,average_DT" ;
float SSS(time, yh, xh) ;
SSS:long_name = "Sea Surface Salinity" ;
SSS:units = "PSU" ;
SSS:missing_value = -1.e+34f ;
SSS:_FillValue = -1.e+34f ;
SSS:cell_methods = "time: mean" ;
SSS:time_avg_info = "average_T1,average_T2,average_DT" ;
double average_T1(time) ;
average_T1:long_name = "Start time for average period" ;
average_T1:units = "days since 0001-01-01 00:00:00" ;
average_T1:missing_value = 1.e+20 ;
average_T1:_FillValue = 1.e+20 ;
double average_T2(time) ;
average_T2:long_name = "End time for average period" ;
average_T2:units = "days since 0001-01-01 00:00:00" ;
average_T2:missing_value = 1.e+20 ;
average_T2:_FillValue = 1.e+20 ;
double average_DT(time) ;
average_DT:long_name = "Length of average period" ;
average_DT:units = "days" ;
average_DT:missing_value = 1.e+20 ;
average_DT:_FillValue = 1.e+20 ;
double time_bounds(time, nv) ;
time_bounds:long_name = "time axis boundaries" ;
time_bounds:units = "days" ;
time_bounds:missing_value = 1.e+20 ;
time_bounds:_FillValue = 1.e+20 ;
...
Sorry, just reread and saw that you had already sorted out the attributes, and found a fix. The 365 days is a good gotcha - another oddity we didn't know about!
Hi! I found something interesting in the MOM6 source code: (directory: MOM6/config_src/drivers/solo_driver/MOM_surface_forcing.F90)
This is within subroutine wind_forcing_from_file(sfc_state, forces, day, G, US, CS):
...
call get_time(day, seconds, days)
time_lev_daily = days - 365*floor(real(days) / 365.0)
if (time_lev_daily < 31) then ; time_lev_monthly = 0
elseif (time_lev_daily < 59) then ; time_lev_monthly = 1
elseif (time_lev_daily < 90) then ; time_lev_monthly = 2
elseif (time_lev_daily < 120) then ; time_lev_monthly = 3
elseif (time_lev_daily < 151) then ; time_lev_monthly = 4
elseif (time_lev_daily < 181) then ; time_lev_monthly = 5
elseif (time_lev_daily < 212) then ; time_lev_monthly = 6
elseif (time_lev_daily < 243) then ; time_lev_monthly = 7
elseif (time_lev_daily < 273) then ; time_lev_monthly = 8
elseif (time_lev_daily < 304) then ; time_lev_monthly = 9
elseif (time_lev_daily < 334) then ; time_lev_monthly = 10
else ; time_lev_monthly = 11
endif
time_lev_daily = time_lev_daily+1
time_lev_monthly = time_lev_monthly+1
select case (CS%wind_nlev)
case (12) ; time_lev = time_lev_monthly
case (365) ; time_lev = time_lev_daily
case default ; time_lev = 1
end select
...
I marked the vital component boldly, you could see there is no case of other time levels except daily cycling and monthly cycling.
So I am thinking how could I add other cases in the source code and make the ball of my project rolling...