ICESat-2 and its capabilities for cryospheric research

Understanding the causes and magnitudes of changes in the cryosphere remains a priority for Earth science research. Over the past decade, NASA's and ESA's Earth-observing satellites have documented a decrease in both the areal extent and thickness of Arctic sea ice, and an ongoing loss of grounded ice from Greenland and Antarctic ice sheets. Understanding the pace and mechanisms of these changes requires long-term observations of ice-sheet mass, sea-ice thickness, and sea-ice extent.

NASA's Ice, Cloud, and land Elevation Satellite (ICESat) mission, which operated from 2003 to 2009, pioneered the use of laser altimeters in space to study the elevation and freeboard of the Earth's ice sheets, glaciers, and sea ice. Since ICESat stopped collecting data in October 2009, the IceBridge and CryoSat-2 missions continue these important observations. Unlike ICESat, which had a single laser beam with a 70-m footprint and took measurements at 150 m along-track intervals, ICESat-2 has three pairs of beams, each pair separated by about 3 km across-track with a pair spacing of 90 m. The spot size is 17 m with an along-track sampling interval of 0.7 m. This measurement concept is a result of the lessons learned from ICESat. The multi-beam approach is critical for estimating cross-track slope around the margins of Greenland and Antarctica enabling the calculation of elevation change on a seasonal basis. For sea ice, the dense spatial sampling (eliminating along-track gaps) and the small footprint size are especially useful for sea surface height measurements from, often narrow, leads which are needed for sea ice freeboard and ice thickness measurements. Additionally, the three pairs of beams provide significantly better spatial coverage. The talk with illustrate the concept of ICESat-2, its potential for polar research, and hopefully some initial performance metrics and data.