README.txt

James Ryan

8 August 2025

This contains the scripts used to make the figures and analyze extreme air masses in "A Worldwide Climatology of Extreme Air Masses," submitted in August 2025.

For comparison, and as a database, we also include the results as .mat files for extreme hot and cold airmasses, using our default parameters.
These have dimensions of 288 longitudes x 180 latitudes x 14976 days, with a 1 if it is an extreme air mass at that point/time, and 0 if not.

The two data files given are named based on the parameters used to generate them, so the one starting with "t5" is for extreme cold, based on the 5th percentile, and the "t95" file is for extreme heat, based on the 95th percentile. Note that these are thresholds relative to the time of year, so "extreme heat" can happen in winter, along with "extreme cold" in summer.

For these scripts to run successfully, please download MERRA2 2m air temperature data, 1980-2020, as well as nClimGrid daily temperature and precipitation data. 

There are many cd commands as well for changing directories, so please change those before using so figures and files go where you intend

A few add-ons are needed as well: see brewermap by Cynthia Brewer/Stephen23, cc2periodic by Geoff Stanley, and tight_subplot by Pekka Kumpulainen. These can all be downloaded/copied from Matlab's File Exchange

Finally, this is intended for Matlab 2024b, with the Image Processing Toolbox, as some of the commands needed for tracking objects do not work in older versions.

Feel free to play around with the data and see what results you get with different combinations of parameters. 

Contact me with any questions regarding this at jamesmryan96@gmail.com

Thanks,
James Ryan
Indiana University 
