CoAuthors

Kyle Duncan (University of Maryland, USA); Ellen Buckley (University of Maryland, United States); Marissa Dattler (University of Maryland, United States); John Kuhn (NOAA Laboratory for Satellite Altimetry, United States); Laurence Connor (NOAA Laboratory for Satellite Altimetry, United States); Eric Leuliette (NOAA Laboratory for Satellite Altimetry, USA)

After a successful launch on the 15th September 2018, the Advanced Topographic Laser Altimeter System (ATLAS) on ICESat-2 has been acquiring photon counting elevation data over Earth’s polar regions to 88 degrees latitude. We show initial ATLAS performance over the Arctic Ocean and subpolar seas, during ICESat-2’s first year of operations. ATLAS height measurements can be used to derive sea ice freeboard, the height of the sea ice above local sea level, and, in ice-free areas, the sea level anomaly (SLA). Early results suggest excellent agreement in sea ice freeboard across all six ATLAS laser beams. The observations reveal very fine details of sea ice topography including rough, multi-year sea ice floes, pressure ridges within the ice cover, and smooth, level ice surfaces including refrozen leads. ATLAS sea ice observations are validated through comparisons with high-resolution airborne altimetry, obtained during dedicated flight surveys over the central Arctic and Beaufort Sea in Spring 2019. We also assess SLA and dynamic ocean topography (DOT) estimates derived from ATLAS data. We cross-calibrate ICESat-2 SLA and DOT measurements with complementary radar altimeter data from CryoSat-2 and Sentinel-3 in the Arctic Ocean, along with Jason-2/3 and SARAL/AltiKa data in the ice-free areas south of the marginal ice zone. We summarize the utility of ICESat-2 for measuring sea surface height and sea ice freeboard in the polar oceans, and explore its capabilities for measuring seasonal and inter-annual variability during its mission lifetime.