Chemical Initial/Boundary Conditions (IC/BC)
WRF-GC is a regional model. Boundary conditions from a global model are generally required. Initial conditions can be provided by a WRF-GC run or other global models.
You can use MOZART4-GEOS5, CAM-chem, or GEOS-Chem as input for initial/boundary conditions.
The general process is as follows:
Identify which data source you want to use as ic/bc.
Set-up WRF-GC, and run
real.exe
to generatewrfinput_d01
(initial conditions), andwrfbdy_d01
(boundary conditions)Prepare ic/bc inputs into a netCDF format accepted by
mozbc
. (mozbc for WRF-GC is located here)Use mozbc to add these inputs to
wrfinput_d01
and/orwrfbdy_d01
files.Run the WRF-GC model.
Preparing IC/BC file from sources
Using global GEOS-Chem output as IC/BC
Details are available in the PDF getting started guide. A MATLAB script will process global GEOS-Chem outputs to netCDF files accepted by mozbc
, which are then generated into WRF(-GC) initial/boundary files.
Run the GEOS-Chem standard full-chemistry/tropchem simulation at a resolution of 2×2.5/4×5 degree (2×2.5 degree recommended). The running time must cover the WRF-GC simulation period: e.g. if the simulation period of WRF-GC is from 2015-06-10 00:00:00 to 2015-06-20-00:00:00 (UTC), the time ranges for GEOS-Chem can be from 2015-06-07 00:00:00 to 2015-06-21 00:00:00 (UTC). Output the netCDF diagnostic files every 6 hours (00, 06, 12, 18), including
GEOSChem.SpeciesConc.xxxxxxxxxxxxxx.nc4
(contains instantaneousSpeciesConc_?ADV?
)GEOSChem.StateMet.xxxxxxxxxxxxxx.nc4
(containsMet_PS1DRY
).
Use the MATLAB script
convert_gcoutput_mozart_structure_selected_domain.m
to merge the GEOS-Chem output files and reconstruct the data structure formozbc
to read.
Run the MATLAB script in the GEOS-Chem output file directory. Modify the script before running as follows:
filename_input
: set the input filename as any one of the GEOS-Chem species concentration output files, e.g.GEOSChem.SpeciesConc.20150601_0000z.nc4
.filename_output
: set the output filename freely.simulation_4_5
/simulation_2_25
:
If the resolution of global GEOS-Chem simulation is 2×2.5 degree, please set it as follows:
simulation_4_5 = false;
simulation_2_25 = true;
If the resolution of global GEOS-Chem simulation is 4×5 degree, please set it as follows:
simulation_4_5 = true;
simulation_2_25 = false;
Set the time ranges for output file
startyr = 2015;
endyr = 2015;
startmon = 6;
endmon = 6;
startdate = 7;
enddate = 21;
Set the domain for output file (needs to be larger than your WRF-GC domain)
If the resolution of global GEOS-Chem simulation is 2x2.5:
longitude: 0 (index 1):2.5:357.5 (index 144) latitude: -90 (index 1):2:90 (index 91)
Here is an example:
lon_left = 1; % longitude of western lateral condition
lon_right = 73; % longitude of eastern lateral condition
lat_bottom = 46; % latitude of southern lateral condition
lat_upper = 91; % latitude of northern lateral condition
The netCDF file will be generated after running the script.
Using MOZART4-GEOS5/WACCM as IC/BC
Refer to the WRF-Chem documentation.
Using mozbc
Building mozbc (only need to do once)
Download a customized version of mozbc for WRF-GC’s hybrid sigma-eta grid. This is available at Xu Feng’s GitHub, fengx7/mozbc_for_WRFv3.9
git clone https://github.com/fengx7/mozbc_for_WRFv3.9.git mozbc
Go to the mozbc directory downloaded and configure the environment. Set up the path to your netCDF library
export NETCDF_DIR=/path/to/netcdf/here
The content inside $NETCDF_DIR
should have include
, … folders that correspond to netCDF.
Compile mozbc. Run
./make_mozbc
.
Configuring mozbc
Edit the input configuration file ending in .inp
, corresponding to the version of GEOS-Chem you are using.
GEOS-Chem 12.8.x: GEOSCHEM_v12_8_1.inp
GEOS-Chem 12.2.1: GEOSCHEM_v12_2_1.inp
Configure the paths to the WRF input in dir_wrf
(wrfinput_d01
, wrfbdy_d01
… - run real.exe to generate these first) and the source netCDF file for IC/BC (created in step above). Make sure the paths end in trailing slashes (/
)
dir_wrf = '/my/path/to/WRF/run/'
dir_moz = '/my/path/to/source/data/for/ic-bc/'
fn_moz = 'wrfgc_icbc_data_test1.nc'
Run mozbc
:
./mozbc < input.inp
Note
If you want to change the species mapping or add new species, please modify the spc_map
in the input file, e.g.: 'isoprene -> ISOP'
where “isoprene” is the name of WRF-GC chemical species and “ISOP” is the name of GEOS-Chem species.
If the chemical IC/BC have been successfully written into the wrfinput_d<domain>
and wrfbdy_d<domain>
files, “bc_wrfchem completed successfully” will appear.