Climatology and Interannual Variations in Arctic Winter Sea Ice Leads in the ICESat-2 Era

Abstract. Sea ice leads play a key role in polar air-sea heat, moisture, and gas exchanges, ocean heat and salinity variations, and ecosystem processes. However, their small-scale nature challenges efforts to assess spatiotemporal variability on a pan-Arctic basis. Here, we use six years of high spatial resolution surface type (ATL07) and freeboard (ATL10) products from Ice, Cloud, and Land Elevation Satellite-2 (ICESat-2) to characterize Arctic winter sea ice leads. Both products reveal consistent climatological spatial patterns, with lead fractions generally higher near the ice edge and coastal regions, and lower over the central abyssal plains. Lead sizes follow a power-law distribution, with the exponent increasing with size. We identify four distinct features in the temporal evolution of lead fraction over the ICESat-2 era, including a maximum in winter 2020–2021; increases in lead fraction are primarily driven by changes in the number of larger (>100 m) leads. Our findings show that ICESat-2 measurements provide robust regional-scale characterization of spatiotemporal variability in winter ice leads, which will in turn better inform their underlying response to, and influence on, Arctic climate.