Overview

This page is part of the Chemistry Model (CHEM) documentation.
It contains a listing of the chemistry mechanisms included in PALM.
For an overview of all CHEM-related pages, see the CHEM main page.

Chemistry mechanism

Currently PALM-4U includes the following sample of chemistry mechanisms:

• cbm4: Carbon Bond Mechanism (Gery et al. (1989), 32 compounds, 81 reactions)
  
• smog: Photochemical smog mechanism (13 compounds, 12 reactions)
  
• simple: Simplified version of SMOG (9 compounds, 7 reactions)
  
• simplep: 'simple' plus one tracer named PM10 (10 compounds, 7 real reactions plus one dummy 'reaction')
  
• phstat: Photo-stationary state (3 compounds, 2 reactions)
  
• phstatp: Photo-stationary state plus one passive tracer named PM10 (4 compounds, 2 real reactions plus one dummy 'reaction')
  

Additional 'mechanisms' are available that describe the transport of one or two passive tracers, i.e. no chemical reactions are necessary:

• passive1: Passive tracers (1 compound, 0 reactions)
  
• passive: Passive tracers (2 compounds, 0 reactions)
  

This list will be extended further in the future.

The standard mechanism which is in the SOURCE directory is 'phstatp'.

In order to select and apply a certain mechanism from this sample, please copy the respective ready-to-use chem_gasephase_mod.f90 from UTIL/chemistry/gasphase_preproc/mechanisms/def_MECH (where MECH stands for any of the available mechanisms) into the USER_CODE directory of the respective simulation Setup, i.e. .../JOBS/<run_identifier>/USER_CODE/chem_gasphase_mod.f90.

Alternatively, the chemistry preprocessor can be executed also for the available machanism in order to create chem_gasphase_mod.f90 (although for the available mechanisms this is not necessary because the chem_gasphase_mod.f90 files are already existing) instead of copying chem_gasphase_mod.f90: Enter the directory UTIL/chemistry/gasphase_preproc and apply the run script, i.e. run_kpp4palm.ksh -m MECH, where MECH stands for any of the mechanisms listed above. The resulting chem_gasphase_mod.f90 will be copied by the script directly into the SOURCE directory.

In order to find out which reactions and compounds are included in the different mechanisms, please have a look into the files MECH.eqn and MECH.spc in UTIL/chemistry/gasphase_preproc/mechanisms/def_MECH.

How to implement a new chemical mechanism or add further passive tracers see the ​Readme-File. If more than two passive tracers or different names of the passive tracers are desired, a new 'mechanism' must be created as described in the Readme file. The Readme file is also available in the PALM-4U subdirectory UTIL/chemistry/gasphase_preproc.