###	GRACE observations of changes in Antarctic land ice mass relative to the 2002 average

###	Data accessed from https://grace.jpl.nasa.gov/data/get-data/jpl_global_mascons on 2026-03-06
    GRACE/GRACE-FO Monthly Mass Grids - Global mascons (JPL RL06.3_v04). https://grace.jpl.nasa.gov/data/get-data/jpl_global_mascons
    
##  Data description
    A multiband Geotiff with each band representing the annual change in Antarctic ice mass relative to the 2002 average (GRACE start), smoothed for visualisation and clipped to Antarctic land mask
     
###	Processing steps:

    1.  Download .nc file from https://grace.jpl.nasa.gov/data/get-data/jpl_global_mascons and store in cwd/input
    
    2.  Run 02_extract_tif.py from cwd
        * Reads monthly lwe_thickness from the NetCDF, apply the internal land_mask, convert to metres water equivalent, and crop south of 60°S
        * Calculates anomalies relative to the mean 2002 baseline and aggregate to cumulative yearly mean anomaly bands
        * Reprojects to a fixed 5 km EPSG:3031 grid using bilinear resampling
        * Applies the Antarctic land-ice display mask and ~100 km Gaussian smoothing
        * Writes a multiband COG to cwd/output, with one band per year representing cumulative mass anomaly relative to the 2002 baseline