Ice Floe Segmentation of MODIS imagery version 2

Daily sea ice floe segmentation for the Beaufort Sea derived from MODIS Terra true-color imagery, 1 March – 30 September (day of year 60–273), 2000–2022. Each day provides a labeled floe map on the NSIDC Polar Stereographic North grid (EPSG:3413, 256.0189 m pixels, 4712 × 4579), a per-floe properties table, and daily aggregate statistics including sea ice concentration and floe size distribution parameters.

This is version 2 and supersedes version 1. Version 1 contained a bug in the ice/open-water thresholding that produced large numbers of spurious single-pixel and few-pixel "floes" from noise within the ice pack, and a label overflow that wrapped floe IDs above 255. Both are corrected here. Users of version 1 should migrate: the floe count, floe size distribution, and power-law exponent are all materially affected.

What changed since v1

• Open-water threshold. The open-water cut is now placed on the low-intensity shoulder of the ice mode (ice shoulder fraction 0.10) rather than at half the height of the ice peak. The v1 placement fell inside the ice mode itself and fragmented the pack into speckle.
•          Large floe statistics. Removing the speckle raises the 99th-percentile floe area, because spurious small floes no longer depress the upper percentile.
•          Hole fraction. A bug that misaligned the per-floe hole_frac column with floe labels after renumbering is fixed.
•         Sea ice concentration. Mean SIC increases by 0.033 (median +0.075), rising in 22 of the 23 years.
•         Data types. Label rasters are now int32. In v1 they were uint8, so labels above 255 wrapped and distinct floes shared an ID.
•         New column. Per-floe tables retain all v1 columns and add area_km2 (pixel area 0.0655 km²).

Contents. segmentation_output_YYYY.zip (one per year: labeled GeoTIFFs and per-floe CSVs), df_stats_all.csv (daily aggregate statistics for the full archive), README.md, and CHANGELOG.md.

Citation. Please cite the concept DOI 10.5281/zenodo.11553699, which always resolves to the current version, together with Buckley et al. (2024), The Cryosphere, doi:10.5194/tc-18-5031-2024.

related identifier: 10.5194/tc-18-5031-2024