EXERCISE 2

Exercise 2: Adding the Global emissions data (sea salt, biomass burning) to the Southeastern Asia domain.

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1. Be sure your environmental variables are set. You don't have to compile WRFV3, but it is always a good idea to have them set. Also, remember to work in
   your directory /home/${USER} .

   
   

2. Copy the chemical emissions from the DATA directory to your home directory.
   cp /DATA/WRF-CHEM/exercise_2/wrfchemi_d01_global wrfchemi_d01_global
   cp /DATA/WRF-CHEM/exercise_2/wrfchemi_gocart_bg_d01 wrfchemi_gocart_bg_d01
   cp /DATA/WRF-CHEM/exercise_2/wrffirechemi_d01 wrffirechemi_d01
   
   

   The emissions input data files needed for this exercise are:

   wrfchemi_d01_global -> Anthropogenic emissions (RETRO/EDGAR)

   wrffirechemi_d01 -> Surface biomass burning fields

   wrfchemi_gocart_bg_d01 -> GOCART background fields

   
   

3. Next "cd" to WRFV3/test/em_real and set the correct options for emiss_inpt_opt, emiss_opt and chem_opt and all of the io_form_auxinput options, etc. in the namelist.input file. In this exercise we will use the simple GOCART aerosol option (chem_opt=300) and global RETRO/EDGAR emissions (emiss_opt=5) with dust, sea salt, DMS, and biomass burning. No need to include biogenic emissions as GOCART aerosols uses just the so2 and aerosol related emissions. Remember, in column 8 of the registry.chem file the auxiliary input port numbers are set and they have been assigned as:

   auxinput_5 -> Anthropogenic emissions

   auxinput_6 -> Biogenic emissions (BEIS, MEGAN)

   auxinput_7 -> Surface biomass burning fields

   auxinput_8 -> GOCART background fields

   auxinput_12 -> Chemistry initial fields

   auxinput_13 -> Volcanic ash emissions

   auxinput_14 -> Aircraft emissions

   auxinput_15 -> Green House Gas emissions

   
   

4. Use a netCDF data file viewer to examine your global emissions data. Does it look like it matches your domain (SE Asia), or a bunch of diagonal lines? It should look like the Malaysia region. Is there fire emissions over the different islands?
   

   
   

5. Now link the global anthropogenic emissions so that it can be used in the simulation. This name is what one would normally use in a run.

   ln -sf wrfchemi_d01_global wrfchemi_00z_d01

   The name wrfchemi_00z_d01 is normally used in a WRF run when emiss_inpt_opt=1 so it should become familiar. But note: IF you are using hourly emissions data - not daily global surface data from RETRO/EDGAR - there will be two wrfchemi files. The first, wrfchemi_00z_d01 containing data from 00 to 11 UTC and wrfchemi_12z_d01 continaing data from 12 to 23 UTC. The 24 hours of emissions data will be cycled each day.
   
   
6. Examine your namelist.input file making sure you have set the correct values for RETRO/EDGAR anthropogenic emissions, the proper vertical dimensions for global emissions (surface data only), auxiliary file update interval, etc. Be sure to turn on biomass burning, sea salt, DMS, etc. as the GOCART aerosol scheme is being used! Also be sure to have the run time of 7 days as you will be making a WRF simulation and not building global emissions from data files that vary daily or monthly.

   
   

7. With the namelist.input file set you can run real.exe to get the GOCART background fields and biomass burning emissions data input the wrfinput file. If you do not do this there will be zero fields entered for biomass burning, etc. when you run wrf.exe

   mpirun -np 4 real.exe

   Examine the wrfinput data file. Do you see the GOCART background fields in the wrfinput_d01 file? Biomass burning emissions (e.g., ebu_in_co) in the surface fields as well?

   
   

8. With the input and boundary conditions files built you can now run wrf.exe. As the biomass burning and GOCART background fields are already in the wrfinput file you need to turn these fields off before running wrf.exe. If you forget you will get a failure reading the input data file message.

   mpirun -np 4 wrf.exe

   It will probably take approximately 5 minutes to finish the simulation on your computer.

   *** An important item to remember is that the GOCART background fields are reset for each chemistry time step. A small chemistry time step will result in an inacurate background state as it takes about 1 hour for the background fields to recover. Be sure to use a reasonable chemical time step like chem_dt = 60 when running the simple GOCART option (chem_opt=300). IF (and that is a big IF) you did not use a large time step for the simple GOCART simulation, rerun with chem_dt = 60 (minutes). But what about chem_opt=301 and 302 (GOCART + RADM2 or RACM gas chemistry)? Those options have the oxidizing chemistry updating with chemdt so the GOCART background fields are not being used for the gas-phase chemistry calculation. For those options use a reasonable chemistry timestep (chemdt = n * time_step; n=0,1,2,3,...). ***

   
   

9. Once again, when finished you should examine results of your simulation. Verify that sea salt aerosols exist in the run. Are the SO2 and fire emissions correct?

   Can you see the fire emissions in the PM, or CO fields above the surface? Does the sea salt match the fine coarse particulate matter fields (PM10)?

   
   
   OPTIONAL: Turn on the aerosol optical properties (e.g., aer_op_opt, opt_pars_out) to obtain the extinction coefficient in the wrfout file and rerun the simulation. Examine the EXTCOEF fields. Are these fields non-zero? Do the higher values correlate with locations of higher aerosol concentration? The vertical sum of each EXTCOEF field is the computed Aerosol Optical Depth (AOD) at a particular wavelength.
   
   

   This concludes WRF-Chem Southeastern Asia domain tutorial exercise 2.

   
   
   
   
   
   To compare solutions, download desired files from here.
   
   

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