Sandbox

Instructions for adding tracers to GEOS-Chem

By Melissa Payer

These instructions describe how to add advected tracers to GEOS-Chem. Advected tracers are carried in the STT array (which is declared in GeosCore/tracer_mod.F), and are transported by the winds.

NOTE: Some advected tracers are also chemical species, which comprise GEOS-Chem's NOx-Ox-HC-aerosol chemistry mechanism.

1. Add tracers to input.geos under Tracer Menu

   1. Increase “Number of tracers” accordingly

   2. Add tracer number, name, molecular weight, and emitted species to end of tracer list

2. Add tracer(s) to restart file – see separate instructions

3. Modify the following source code routines:

   1. Headers/CMN_SIZE_mod.F

      1. Increase NNPAR by number of tracers being added

      2. If the species have anthropogenic emissions, increase NEMPARA accordingly

      3. If the species have biogenic emissions, increase NEMPARB accordingly

      4. If the species have biomass burning emissions, increase NBIOMAX accordingly

   2. GeosCore/tracerid_mod.F

      1. Increase NNNTRID by the number of tracers being added NOTE: NNNTRID must be equal to NNPAR in CMN_SIZE_mod.F

      2. Define tracer IDs as needed:

         1. IDxxxx – ID for SMVGEAR species

         2. IDTxxxx – GEOS-Chem tracer ID

         3. IDExxxx – GEOS-Chem emission ID

         4. IDBFxxxx – GEOS-Chem biofuel ID

         5. IDBxxxx – GEOS-Chem biomass ID

      3. In subroutine TRACERID,

         1. Under “Assign tracer, biomass, biofuel, and anthro emission ID’s,” add case for added tracers to initialize IDTxxxx, IDBFxxxx, IDBxxxx

         2. Under “Initialize the IDExxx flags,” add IF statement for added tracer IDs and initialize IDExxxx

         3. Under “Fill IDEMS with appropriate tracer ID #’s,” add IF statement for added tracers

         4. Under “Print additional information,” add WRITE statements for added tracers

      4. In subroutine SETTRACE (NOTE: Only do the following if species is included in SMVGEAR chemical mechanism

         1. Add IF statement, to initialize IDxxxx

         2. In subroutine INIT_TRACERID,

         3. Zero all IDs added (IDxxxx, IDTxxxx, IDExxxx, etc.)

   3. Other modules that may need to be updated include:

      1. wetscav_mod.F

      2. drydep_mod.F

      3. emissions_mod.F

      4. biomass_mod.F

      5. biofuel_mod.F

         etc.

Instructions for adding species to GEOS-Chem

Modify run directory files

1) Add tracers to input.geos under Tracer Menu c) Increase “Number of tracers” accordingly d) Add tracer number, name, molecular weight, and emitted species to end of tracer list

2) Add tracer(s) to restart file – see separate instructions

3) Modify globchem.dat to include additional species, kinetic reactions (including emissions and drydep), or photolysis reactions NOTE: If you modify globchem.dat and plan to run GEOS-Chem using the KPP chemical solver, you will need to generate new gckpp*.F90 files. For more information see the following wiki pages: http://wiki.seas.harvard.edu/geos-chem/index.php/KPP_solvers_FAQ#What_are_the_cons_of_using_KPP.3F http://wiki.seas.harvard.edu/geos-chem/index.php/Interfacing_GEOS-Chem_with_KPP#Generating_KPP_input_files_from_GEOS-Chem_globchem.dat

4) If necessary, modify: a) ratj.d – contains species names and branching ratios for FAST–JX photolysis species For more information: http://acmg.seas.harvard.edu/geos/doc/man/chapter_5.html#5.4.1 b) jv_spec.dat – contains cross-sections and quantum yields for FAST–JX photolysis species For more information: http://acmg.seas.harvard.edu/geos/doc/man/chapter_5.html#5.4.3