### Southern Ocean pinnipeds provide bathymetric insights on the East Antarctic continental shelf

### Data downloaded from http://doi.org/10.26179/s37r-xs33 on 2025-10-05
    Hindell, M.A. and McMahon, C. (2023) Southern Ocean pinnipeds provide bathymetric insights on the East Antarctic continental shelf, Ver. 1, Australian Antarctic Data Centre. http://doi.org/10.26179/s37r-xs33

### Processing steps:

    1.  Recalculate IBCSO v2 bathymetry values for seal dives because errors were identified in IBCSO2 (and calculated dfb) values supplied with dives.csv.
        * Download IBCSO v2 Bed Elevation from https://doi.org/10.1594/PANGAEA.937574
        * Resample to 2,500 m (and optionally 10,000 m) in EPSG:3031 using (bilinear resampling)
        * Extract bathymetry values at each seal dive location
            - ibcso2_raw    = non-resampled IBCSO value
            - ibcso2_2500   = IBCSO value resampled to 2,500 m
            - ibcso2_10000  = IBCSO value resampled to 10,000m
        * Calculate the difference between maximum dive depth and IBCSO bathymetry
            - dfb_raw       = ibcso2_raw - max_depth
            - dfb_2500      = ibcso2_2500 - max_depth
            - dfb_10000     = ibcso2_10000 - max_depth

    2.  Run 02_grid_dives.py
        * Selects the deepest dive within each user-specified grid cell
        * Outputs Cloud-Optimised GeoTIFFs in EPSG:3031
        * Optionally retain only dives deeper than the corresponding IBCSO bathymetry (positive dfb value)
        * Outputs:
          - data\sealdives_maxdepth_25.tif   = maximum depth of any seal dive within a 2,500 m cell
          - data\sealdives_maxdepth_100.tif  = maximum depth of any seal dive within a 10,000 m cell

    3.  Clip the resampled IBCSO surface to the seal-dive area of interest and retain depths between 0 and -2,500 m.
        * Outputs:
          - ibcso\IBCSO_clip_25.tif  = IBCSO surface gridded to 2,500 m and clipped to AoI
          - ibcso\IBCSO_clip_100.tif = IBCSO surface gridded to 10,500 m and clipped to AoI    

    4.  Align the gridded seal-dive raster to the corresponding IBCSO grid.

    5.  Create the augmented bathymetric surface by replacing IBCSO values where the observed seal dive is deeper than the mapped seabed.
        * ArcGIS Pro: Raster Calculator [OutRaster = Con( "grid_xres_sealdive" < "IBCSO_xres", "gridded_xres_sealdive", "IBCSO_xres" )
        * Outputs:
          - output\sealdives_depthdelta_25.tif  = difference between IBCSO and max dive depth (gridded to 2.5km)
          - output\sealdives_depthdelta_100.tif = difference between IBCSO max dive depth (gridded to 10km)
          - output\merged_bathy\sealdives_IBCSO_merge_25.tif  = new seal dive augmented IBCSO surface (gridded to 2.5km)
          - output\merged_bathy\sealdives_IBCSO_merge_100.tif = new seal dive augmented IBCSO surface (gridded to 10km)