.. _aerosol_output:

Aerosol diagnostics and output
==============================


Configuring a run with more aerosol diagnostics in NorESM2
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
To run NorESM2 with more aerosol diagnostics add to user_nl_cam:
:: 

  &phys_ctl_nl 
    history_aerosol = .true. 
    


Adding ``history_aerosol = .true.`` to ``user_nl_cam gives`` additional 577 variables (+ ca. 13 % CPU-time).
Please see an overview of additional output varibales: :ref:`aerosol_output_history_aerosol_variables`

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). To enable this, copy the file ``preprocessorDefinitions.h`` from to the ``SourceMods/src.cam/`` folder in your case directory::

  cp <noresm_base>/components/cam/src/physics/cam_oslo/preprocessorDefinitions.h <case_folder>/SourceMods/src.cam/.

To change the preprocessor definition to true, i.e. replace::
 
  #undef AEROFFL
  
with::

  #define AEROFFL

in the ``preprocessorDefinitions.h`` file.

The **AEROFFL**-token tells the model to do additional radiation-diagnostics for aerosol indirect effect. Including::

  #define AEROFFL
  
to ``preprocessorDefinitions.h`` gives 8 additionally variables (+ ca. 5% CPU-time). Please see an overview of the additional output variables: :ref:`aerosol_output_aeroffl_variables`


Enable diagnostics for AEROCOM
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
NorESM2 can be set up to take out additional aerosol output for use in AeroCom (https://aerocom.met.no/index.html) or other studies where there is a need for extensive aerosol diagnostics. To enable this, copy the file ``preprocessorDefinitions.h`` from to the ``SourceMods/src.cam/`` folder in your case directory::

  cp <noresm_base>/components/cam/src/physics/cam_oslo/preprocessorDefinitions.h <case_folder>/SourceMods/src.cam/.

To change the preprocessor definition to true, i.e. replace::
 
  #undef AEROCOM
  
with::
 
  #define AEROCOM

in the ``preprocessorDefinitions.h`` file.

If #define AEROCOM is activated, we additionally get 149 variables (+ ca. 13% CPU-time). Please see an overview of the additional output variables: 
:ref:`aerosol_output_aerocom_variables`



**The model may be run with any combination of these options: with AEROFFL only, with AEROCOM only, or with AEROFFL and AEROCOM activated at the same time.**


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