Exploring High-resolution Observations of Arctic Sea Ice with ICESat-2

Satellite observations indicate declines in the extent, thickness and age of Arctic sea ice over four decades. The ongoing collapse of the Arctic sea ice cover not only has serious implications for Earth's climate, but also wide-ranging ecological and socio-economic impacts. Understanding how the sea ice cover varies in both space and time is required to characterize the physical processes governing change, and to improve predictions of the future Arctic climate system. The Advanced Topographic Laser Altimeter System on ICESat-2 offers a new remote sensing capability to measure complex sea ice surface topography at high resolution. We provide an overview of the first two years of sea ice retrievals, tracking the evolution of the ice cover between Fall 2018 and Fall 2020. ICESat-2 measurements span the entire growth and melt periods, allowing us to observe both ice thickening in winter, and ice pack deterioration in summer. Because of its unique, high resolution, coupled with the spatial and temporal extent of data acquisition, ICESat-2 provides novel observations of time-varying dynamic and thermodynamic sea ice processes. Here we highlight the retrieval of six sea ice parameters from ICESat-2 data including surface roughness, ridge height, ridge frequency, melt pond depth, floe size distribution, and lead frequency. Our results demonstrate that these sea ice properties can be observed routinely, and in fine detail, across broad regions and ice conditions, using satellite altimetry techniques.