[x] Use the spatialdata repo as a model for bringing in SPEI data
[x] Investigate the different SPEI indices (feel free to assign me reading as well!) Ideally they have an annual product that we will link up with SRDB data
[x] If we end up using monthly, want to think/do research about what to use (average? Max? ...?) -> in this case, there will be a "compute annual value" step resulting in {site, year, value}
[ ] Once SPEI is merged (will be based on location AND time) with SRDB data, make some maps!
Bonus time:
[ ] The spatialdata repo also has a WorldClim example, which we will want at some point: climatology (average conditions) for each site