FCnudged and FHIST AODSVIS differences

[nuvolet]

Greetings,

Assuming that using compset FCnudged and FHIST, for the atmosphere, they differ by:

FCnudged: CAM cam6 physics:CAM-Chem troposphere/stratosphere chemistry with simplified VBS-SOA

FHIST: CAM cam6 physics

I was wondering if that explains why both compsets have different AODVIS in the history files.

Thanks in advance

 

[nuvolet]

Here there is an example plot for the AODVISdn differences for AODVISdn for FCnudged and FHIST compsets using MERRA2 re-analisys.

 

[brianpm]

Maybe I'm not quite understanding your question, but I wouldn't expect AODVIS to be the same between these configurations.

- As you noted, the chemistry is different between CAM-Chem and CAM6, which will lead to different aerosol fields, I think.
- I'm not sure whether the initial condition is the same between these compsets, but if not, that would also result in different weather
- Depending on how far into the simulation you are looking, the weather will be quite different between the one nudged to MERRA and the free-running FHIST.

Just to be clear about it: "FHIST" is a land-atmosphere configuration that uses observed SST and sea-ice as lower boundary conditions, and uses observed GHG concentrations and aerosol emissions. The weather is not expected to follow the observed weather. The nudged configuration is continuously relaxed to the specified data set (here MERRA), so the atmospheric state (the weather) is much more strongly constrained.

Hope that helps. Please feel free to follow up if not.

 

[nuvolet]

Maybe I'm not quite understanding your question, but I wouldn't expect AODVIS to be the same between these configurations.

- As you noted, the chemistry is different between CAM-Chem and CAM6, which will lead to different aerosol fields, I think.
- I'm not sure whether the initial condition is the same between these compsets, but if not, that would also result in different weather
- Depending on how far into the simulation you are looking, the weather will be quite different between the one nudged to MERRA and the free-running FHIST.

Just to be clear about it: "FHIST" is a land-atmosphere configuration that uses observed SST and sea-ice as lower boundary conditions, and uses observed GHG concentrations and aerosol emissions. The weather is not expected to follow the observed weather. The nudged configuration is continuously relaxed to the specified data set (here MERRA), so the atmospheric state (the weather) is much more strongly constrained.

Hope that helps. Please feel free to follow up if not.

Hi Brian,

Both cases have same initial conditions:

  ./create_newcase --case FCnudged_control --compset FCnudged --res f09_f09_mg17  --run-unsupported       
  ./case.setup
  ./xmlchange RUN_STARTDATE=2008-01-01,STOP_OPTION=ndays,STOP_N=2,DOUT_S=FALSE

and

  ./create_newcase --case FHIST_control --compset FHIST --res f09_f09_mg17  --run-unsupported       
  ./case.setup
  ./xmlchange RUN_STARTDATE=2008-01-01,STOP_OPTION=ndays,STOP_N=2,DOUT_S=FALSE

While the nudging_nl is described for both cases in user_nl_cam file as:

&nudging_nl
nudge_model            = .true.
model_times_per_day    = 48
nudge_times_per_day    = 8
nudge_timescale_opt    = 1       
nudge_path             = '/glade/p/cesmdata/cseg/inputdata/atm/cam/met/nudging/MERRA2_fv09_32L/'
nudge_file_template    = '%y/MERRA2_fv09.cam2.i.%y-%m-%d-%s.nc'
nudge_force_opt        = 0
nudge_pscoef           = 0.00
nudge_psprof           = 0
nudge_qcoef            = 0.25
nudge_qprof            = 1
nudge_tcoef            = 0.25
nudge_tprof            = 1
nudge_ucoef            = 0.25
nudge_uprof            = 1
nudge_vcoef            = 0.25
nudge_vprof            = 1
/

Both runs, FCnudged and FHIST, are nudged by the MERRA re-analisys.

Thanks

 

[brianpm]

If you have confirmed that your FHIST run is being nudged correctly, then I think you are right that the difference is the chemistry.

 

[brianpm]

Well... I guess you should also confirm that everything else is the same too... like all the emissions files, the atmospheric composition, the ozone file, the land setup.