PyChEmiss
is a Python script to create the wrfchemi
file from local emissions needed to run WRF-Chem model. It's based on his older broder AAS4WRF.ncl.
You need to install the packages that PyChEmiss
needs. We recommend to use
miniconda or
anaconda
You can download this repo or clone it by:
git clone https://github.com/quishqa/PyChEmiss.git
Then add conda-forge
channel by:
conda config --add channels conda-forge
To avoid conflicts during the installation, we also recommend create a new environment to run PyChEmiss
:
conda create --name PyChEmiss
conda activate PyChEmiss
Now you can install espmy
, xesmf
and pyyaml
. By doing this, xarray
,
numpy
, and pandas
will be also installed:
conda install esmpy
conda install xesmf
conda install pyyaml
It's important to first install esmpy
to avoid this issue.
Or, you can install the packages located in requirements.txt
by typing:
conda install --yes --file requirements.txt
If everything goes well, you are ready to go.
To run this script you need the wrfinput_d0x
and your temporal and spatial disaggregated emissions in mol/km2/hr. You can see the needed format by exploring emissions_3km.txt
file.
To untar the example files:
tar -zxvf emissions_3km.tar.gz
tar -zxvf wrfinput_d02.tar.gz
This file controls some parameters to run the script. ""
are required only in sep
.
wrfinput_file
: the location of wrfinput_d0x.emission_file
: the location of the local emission file.nx
andny
: the number of longitude and latitude points in which local emission were spatially disaggregated.cell_area
: cell area in km2 of inputemission_file
.start_date
andend_date
:emissions_3km.txt
temporal availability in%Y-%m-%d %H:%M
format.header
: If your local emission file has a header.col_names
: Names of emission file column names. Remember that the three first columns have to be named "i", "lon", and "lat".sep
: Column delimiter in emission file. Use quotes (""
)method
: we implementnearest_s2d
methods for emissions regridding (a conservative method is on the way!).output_name
: location and name of producedwrfchemi
file (wrfchemi_d02_pychemiss
)
To run the script, type:
python pychemiss.py pychemiss.yml
To check that everything is working properly up to this point, we recommend to visualize the content of the output file, for example, by using ncview
ncview wrfchemi_d02_pychemiss
To use the wrfchemi
file in a standard WRF-Chem simulation, change its name from wrfchemi_d02_pychemiss
to wrfchemi_d<domain>_<date>
(wrfchemi_d01_2018-06-21_00:00:00
in this example) and set some control parameters in the namelist.input
file as follows
&time_control
io_form_auxinput5 = 2,
auxinput5_inname = 'wrfchemi_d<domain>',
auxinput5_interval_m = 60,
frames_per_auxinput5 = 240,
/
&chem
io_style_emissions = 2,
/
240 is the number of times (hours) in the wrfchemi
file.
For 24 hours of emissions data, the preprocessor will automatically build two 12-hour emission files: wrfchemi_00z_d02
(00 to 11 UTC) and wrfchemi_12z_d02
(12 to 23 UTC). In this case, set frame_per_auxinput5
to 12 and io_style_emissions
to 1.
Here there is a comparison between the local emission of CO (with ΔX= 3 Km) and the
output after using pychemiss.py
for a WRF domain of ΔX = 3 km.
For a WRF domain with 150 x 100 points and for ten days with hourly emissions (nx =30 and ny=27, like the above figure), in a "normal" laptop, it took 30 seconds to run.