### Antarctic polynya database

### Data downloaded from https://doi.org/10.6084/m9.figshare.24768654.v1 on 2025-11-20
    Duffy, Grant (2024). Duffy et al. - Antarctic polynya database. figshare. Dataset. https://doi.org/10.6084/m9.figshare.24768654.v1
    
### Description
    Boundaries of polynyas extracted from binary ≤50% threshold daily sea ice concentration data, 1979-2022.
    
### Processing steps

    1.	Download 50% threshold Shapefile data from https://doi.org/10.6084/m9.figshare.24768654.v1

    2.  Dissolve data on polyID and day, month or year.

    3.  Run 02_make_freq_raster.py from cwd
        * Generates a 25 km resolution polynya frequency raster, with each cell representing the number of days a polynya was present at that location (1979–2022)
        * Outputs Int32 COG in EPSG:3031, NoData = -9999