Weather data was extracted from MERRA-2 by the subsetting approach. The MERRA-2 are stored in netCDF format with each file is for a timestamp of analysis with the grid covers the entire globe. To extract limited numbers of sites, subsetting via OpeNDAP is affordable with limited storage space, bandwidth and computing powers.
The PM2.5 data is stored in the .CSV files accessible via the AirNow.gov website. The files are ready for analysis with minimal efforts to clean up.
All extracting, cleaning and analyzing data are carried out with Python and its libraries such as Pandas, Matplotlib. All of data and tools used in this report are free and open access.