- What would be the right way to switch off a process like dry deposition altogether, or just switch off ozone dry deposition to leaves stomata only in CMAQ (newest version)?
- What is the easiest way of setting input CMAQ BC of select species to zero?
You should be able to turn off dry deposition for a specific gas phase species by editing the GC namelist file, specifically by changing the factor in the βFACβ column to the right of the βDRYDEP SURRβ column from 1 to 0. For example, to switch off ozone dry deposition, change the beginning of the GC namelist file from
&GC_nml
GC_SPECIES_DATA =
!SPECIES ,MOLWT ,IC ,IC_FAC,BC ,BC_FAC ,DRYDEP SURR ,FAC ,WET-SCAV SURR ,FAC ,GC2AE SURR ,GC2AQ SURR,TRNS ,DDEP ,WDEP ,CONC
βNO2β , 46.0 ,ββ ,-1 ,ββ ,-1 ,βVD_NO2β , 1 ,βNO2β , 1 ,βNO2β ,ββ ,βYesβ ,βYesβ ,βYesβ ,βYesβ,
βNOβ , 30.0 ,ββ ,-1 ,ββ ,-1 ,βVD_NOβ , 1 ,βNOβ , 1 ,ββ ,ββ ,βYesβ ,βYesβ ,βYesβ ,βYesβ,
βOβ , 16.0 ,ββ ,-1 ,ββ ,-1 ,ββ ,-1 ,ββ ,-1 ,ββ ,ββ ,ββ ,ββ ,ββ ,βYesβ,
βO3β , 48.0 ,ββ ,-1 ,ββ ,-1 ,βVD_O3β , 1 ,βO3β , 1 ,ββ ,βO3β ,βYesβ ,βYesβ ,βYesβ ,βYesβ,
to
&GC_nml
GC_SPECIES_DATA =
!SPECIES ,MOLWT ,IC ,IC_FAC,BC ,BC_FAC ,DRYDEP SURR ,FAC ,WET-SCAV SURR ,FAC ,GC2AE SURR ,GC2AQ SURR,TRNS ,DDEP ,WDEP ,CONC
βNO2β , 46.0 ,ββ ,-1 ,ββ ,-1 ,βVD_NO2β , 1 ,βNO2β , 1 ,βNO2β ,ββ ,βYesβ ,βYesβ ,βYesβ ,βYesβ,
βNOβ , 30.0 ,ββ ,-1 ,ββ ,-1 ,βVD_NOβ , 1 ,βNOβ , 1 ,ββ ,ββ ,βYesβ ,βYesβ ,βYesβ ,βYesβ,
βOβ , 16.0 ,ββ ,-1 ,ββ ,-1 ,ββ ,-1 ,ββ ,-1 ,ββ ,ββ ,ββ ,ββ ,ββ ,βYesβ,
βO3β , 48.0 ,ββ ,-1 ,ββ ,-1 ,βVD_O3β , 0 ,βO3β , 1 ,ββ ,βO3β ,βYesβ ,βYesβ ,βYesβ ,βYesβ,
This is the approach I took for a brute force sensitivity simulation in CMAQv5.0.2 but I have not tested it in newer versions.
To modify and/or switch off specific dry deposition pathways (e.g. stomatal), you would have to work directly with the M3DRY and/or STAGE code. Since modifying that code without in-depth knowledge of its workings can be error-prone, you probably would want to reach out to the developers before embarking on such an analysis.
You can set boundary conditions of selected species to zero by a) using a tool like βcombineβ to modify your existing BCON files to explicitly set these concentrations to zero, b) using a tool like βcombineβ or βm3xtractβ to remove the species you want to be set to zero from your existing BCON files (CMAQ will set boundary conditions to zero - or a very small number - if a given species cannot be found in the BCON file), or c) setting the βBC_FACβ column in the GC namelist file to zero for the desired species.