Datensatz

Zusammenfassung

Leads are narrow, dynamic openings within the sea ice pack. They are of vital importance for heat and moisture exchange between the atmosphere and the ocean, and their distribution and geometry can affect the movement and stability of the surrounding ice. Furthermore, leads are essential for providing safe shipping routes, with sea ice being hazardous to transiting ships. The identification of leads is also crucial for calculating sea ice freeboard from satellite altimetry because the correct discrimination of leads and floes allows the sea surface height to be determined, which is an essential component of sea ice freeboard and thickness calculation. Inaccurate discrimination of leads can therefore lead to systematic errors in estimates of sea ice thickness.Here, we investigate changes in the density and distribution of leads in the Canadian Arctic Archipelago, with a focus on the Northwest Passage due to its strategic and economic interest as a shipping route. Leads and floes are discriminated in CryoSat-2 waveforms using measurements of their pulse peakiness and stack standard deviation, and in Landsat 8 thermal infrared imagery, using a classification of their heat anomalies. We then evaluate the agreement between these two independent estimates, and present the spatial and temporal trends in lead density in the Northwest Passage, thereby assessing how the ice pack is changing in a region of high economic interest. Our results reveal increases in lead density of ~10% in regions of the Northwest Passage since 2010, and we validate these results with over fifty near-coincident optical images.