3. Aerosol diagnostics and output

3.1. Outputing NorESM2 aerosol diagnostics

To run NorESM2 with more aerosol diagnostics add to user_nl_cam:

&phys_ctl_nl
  history_aerosol = .true.

Adding this entry to user_nl_cam gives will result in an additional 577 variables (+ ca. 13 % CPU-time). Please see an overview of additional output varibales: history_aerosol extra output

3.2. Decomposition of aerosol direct, semidirect and indirect radiative forcing

For effective radiative forcing estimates, multiple calls to the radiation code are necessary (see Ghan et al. 2012 for a detailed explanation). Previously, in NorESM2.0, additional radiation-diagnostics for the decomposition of aerosol direct, semidirect and indirect radiative forcing were activated by defining the CPP-token AEROFFL. In NorESM2.1, this CPP-token no longer exists and this additional output always accompanies the standard CAM diagnostics and also does not need the history_aerosol = .true. to be activated. Please see an overview of the additional output variables: Additional Radiation Diagnostics

3.3. Output additional NorESM2 - AEROCOM diagnostics

NorESM2 can be set up to output additional aerosol diagnostics for use in AeroCom (https://aerocom.met.no/index.html) or other studies where there is a need for extensive aerosol diagnostics. In both NorESM2.0 and NorESM21, the CPP token AEROCOM must be defined in order to activate this output. However, in NorESM2.1, this variable is now activated via a new CAM build-time xml variable, CAM_AEROCOM. By default CAM_AEROCOM is FALSE. To activate the CPP token AEROCOM at build time, simply issue the command

./xmlchange CAM_AEROCOM=TRUE

before calling ./case.build. If AEROCOM is activated, an addition 149 variables are output (+ ca. 13% CPU-time). Please see an overview of the additional output variables: AEROCOM extra output

3.4. References

Ghan, S.J., X. Liu, R.C. Easter, R. Zaveri, P.J. Rasch, J. Yoon, and B. Eaton, 2012: Toward a Minimal Representation of Aerosols in Climate Models: Comparative Decomposition of Aerosol Direct, Semidirect, and Indirect Radiative Forcing. J. Climate, 25, 6461–6476, https://doi.org/10.1175/JCLI-D-11-00650.1