Interpolation of GFS all varaibles data in init_atmosphere;

[AstroCrush]

The GFS data I'm going to use as initial condition (IC), has 127 vertical levels, (from 0.01 milibar to 1000 milibar), however this range is not linearly distributed, it is more concentrated in the beginning and in the end, when running the init_atmosphere, how can I set the configs to account for this non linearity when interpolating the data to fit the
&dimensions sub section (config_nvertlevels, config_nsoillevels, config_nfglevels, config_nfgsoillevels; in this case my question is regarding the atmosphere specific parameters)?

Another question is, for more accurate forecasts, should I set config_ztop as 80000.0? Because 0.01 milibar corresponds to 80Km.
In the tutorial file, config_ztop is set to 30000 (30 Km), and config_zd is set to 22000 (22Km), should I keep the same ratio (or value)?

 

[Ming Chen]

Hi,
Please see my answers below:

The GFS data I'm going to use as initial condition (IC), has 127 vertical levels, (from 0.01 milibar to 1000 milibar), however this range is not linearly distributed, it is more concentrated in the beginning and in the end, when running the init_atmosphere, how can I set the configs to account for this non linearity when interpolating the data to fit the
&dimensions sub section (config_nvertlevels, config_nsoillevels, config_nfglevels, config_nfgsoillevels; in this case my question is regarding the atmosphere specific parameters)?

There is no option to account for the nonlinearity of the input data for MPAS. MPAS interpolates GFS data from the nearest levels to the MPAS model levels. Please see the code "core_init_atmosphere/mpas_init_atm_cases.F " for more details.

Another question is, for more accurate forecasts, should I set config_ztop as 80000.0? Because 0.01 milibar corresponds to 80Km.
In the tutorial file, config_ztop is set to 30000 (30 Km), and config_zd is set to 22000 (22Km), should I keep the same ratio (or value)?

config_ztop specified the model top level. It should be determined based on your specific need. If you are concerned of processes in the troposphere, then config_ztop = 30000 should be sufficient.
config_zd is the height above mean sea level to begin w-damping. Again, you can change its value based on your case. There is no strict rule how to set its value, and personally I often set it to be around 10km below the model top.