Ice Charting

Ice charting is the operational mapping of sea-ice conditions for navigation, drawn by national ice services from satellite imagery, ship and aircraft reports, and analyst expertise. The WMO egg code is the symbology: an oval (the egg) holds total and partial concentrations in tenths on the top line, stage of development on the middle line, and floe size on the bottom line, with letters keying to the legend. The egg encodes the same parameters that POLARIS reads, so a chart maps directly to an ice-regime risk assessment. SAR (Sentinel-1), passive microwave (AMSR), and scatterometer data are the primary inputs, refreshed daily through the freezing and melt seasons.