Easy Volcanic Aerosol (EVA v1.0): users guide

(also available as EVAv1_users_guide.pdf)

Structure

The EVA package is composed of:

1. The mo_EVA.f90 FORTRAN module: this holds all the subroutines used to calculate volcanic forcing
2. Three input files in netCDF format:
  a. EVA parameter set, specifying the values to be used for the parameterizations in the mo_EVA routines
  b. An eruption history file, specifying the date, location, stratospheric sulfur injection (in Tg S) and, optionally, the hemispheric asymmetry factor to be applied to each eruption.
  c. A lookup table, containing the scaling factors to convert EXT550 and reff to wavelength dependent EXT, SSA and ASY based on Mie Theory.
3. The FORTRAN program eva_build_sulfate_file.f90, which builds a sulfate file specifying the timeseries of sulfate in the equatorial, NH and SH regions based on the eruption history input file and EVAs three-box model transport scheme.
4. The FORTRAN program eva_build_forcing_files.f90, which builds aerosol property (or forcing) files from the sulfate timeseries.
5. A netCDF file containing specifications of the grids to be used in the output of EVA, i.e., latitude, and wavelength.

Compiling

The FORTRAN routines all make use of the NETCDF fortran library, and so need to be linked to the library upon compilation.
Use gfortran (as below), or your favorite fortran compiler. The variable NETCDF=... (/usr in the example below) must point to your local netcdf installation:

>> NETCDF=/usr
>> gfortran -c mo_EVA.f90 -I${NETCDF}/include
>> gfortran -o eva_build_sulfate_file eva_build_sulfate_file.f90 mo_EVA.o -I${NETCDF}/include -L${NETCDF}/lib -lnetcdff
>> gfortran -o eva_build_forcing_files eva_build_forcing_files.f90 mo_EVA.o -I/usr/include -L/usr/lib -lnetcdff

Pay careful attention to the L and l flags required on your system.

For more information, see:

http://www.csar.cfs.ac.uk/user_information/software/environment/guide.book.pdf
https://www.unidata.ucar.edu/software/netcdf/netcdf-4/newdocs/netcdf-f90.html
http://web.utah.edu/thorne/computing/Examples_netCDF.pdf

Running

Step 1: build sulfate file
The script eva_build_sulfate_file.f90 reads the eruption history file, and based on the parameter settings in EVAv1_parameter_set_v1.0.nc, builds a timeseries of sulfate mass, saved in file eva_sulfate_timeseries.nc.

Once compiled, simply run the script:

 >> ./eva_build_sulfate_file

Step 2: build forcing files
The script eva_build_forcing_files.f90 builds yearly volcanic aerosol forcing files, with aerosol optical properties as a function of time, latitude, height and wavelength. Once the sulfate file is produced via step 1, and eva_build_forcing_files.f90 is compiled, simply run the script:

>> ./eva_build_forcing_files

As a default, this script produces forcing files for the years (YYYY) 1991 through 1995, as eva_forcing_echam_T63_sw_YYYY.nc.
Modifications

New input files

Any of the input files can be readily swapped for alternative files, by changing the filenames given in the mo_EVA.f90 module and recompiling the module. This can be done to change the source of eruption histories, change the parameter setting of EVA, or change the Mie lookup tables. Care must be taken that the variable names and dimensions of the new input files are identical to those of the default input files.

Change time range

To modify the timespan of forcing files produced, simply adjust the start and end years in the eva_build_forcing_files.f90 script, recompile and run. Note that the start and end years given here must be within the years of the sulfate file produced prior. The time range of the sulfate file can be similarly adjusted in the eva_build_sulfate_file.f90 script.

Different model set ups

Modifying the output of EVA to different model specifications is possible by supplying an alternate grid file in the running of the eva_build_forcing_files routine. Care must be taken that the variables in the new grid file have the same names and dimensions as the default grid files (based on the ECHAM model specifications).

