aas4wrf.py

aas4wrf.py 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. Currently, It works with CBMZ/MOSAIC chemical mechanism and for surface emissions.

Installation

You need to install the packages that aas4wrf.py needs. We recommend to use miniconda or anaconda

You can download this repo or clone it by:

git clone https://github.com/quishqa/AAS4WRF.py.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 aas4wrf.py:

conda create --name aas4wrf
conda activate aas4wrf

Option A

Now you can install espmy, xesmf and pyyaml. By doing this, xarray, numpy, and pandaswill be also installed:

conda install esmpy
conda install xesmf
conda install pyyaml

It's important to first install esmpy to avoid this issue.

Option B

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.

The input data

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.txt file.

Configuration file: aas4wrf.yml

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 and ny: the number of longitude and latitude points in which local emission were spatially disaggregated.
• cell_area: cell area in km² of input emission_file.
• start_date and end_date: emissions.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 implement nearest_s2d methods for emissions regridding (a conservative method is on the way!).
• output_name : location and name of produced wrfchemi file (wrfchemi_d02_aas4wrf)

Usage

To run the script, type:

python aas4wrf.py aas4wrf.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_aas4wrf

Output example

Here there is a comparison between the local emission of CO (with ΔX= 3 Km) and the output after using aas4wrf.py for a WRF domain of ΔX = 3 km.

Expected Runtime

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.

WRF-Chem namelist configuration

To use the wrfchemi file in a standard WRF-Chem simulation, change its name from wrfchemi_d02_aas4wrf 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 in the wrfchemi file.