NASA’s ICESat-2 satellite mission was successfully launched from Vandenberg Air Force Base, CA, on September 15th, 2018. The spacecraft carries the Advanced Topographic Laser Altimeter System (“ATLAS”) which obtains precise elevation measurements of ice surfaces, vegetation, land, water, and clouds. ICESat-2 observations help to improve our understanding of climate variability and change, so as to enhance society’s ability to plan and respond.
Dr. Sinéad Farrell, Associate Professor in Geographical Sciences, is a member of the ICESat-2 Science Team and has been working with the project since its inception a decade ago. In its first year, ICESat-2 underwent commissioning, during which time the team carried out crucial evaluations of the ATLAS laser over a wide variety of land surfaces to assess its measurement capabilities. The team recently celebrated ICESat-2’s first, complete year in Earth orbit with a science team meeting at the University of Washington, Seattle, WA. There, the science team learned that ICESat-2 is producing good quality data and the instrument is operating nominally. A variety of elevation data products are now freely available to the science community at the National Snow and Ice Data Center.
The small footprint (~ 14 m), high pulse repetition rate (10 kHz) and six-beam configuration of ATLAS on ICESat-2 provides the highest-fidelity measurements of Earth’s sea ice ever to be obtained from a spaceborne platform. Farrell and her team showed the initial performance of ICESat-2 over Arctic sea ice during its first year of operation. Continual measurements throughout the winter of 2018/2019 tracked the evolution and growth of the ice cover. Early discoveries include high-resolution measurements of sea ice surface roughness, indicating pressure ridging and convergence of ice floes colliding under the influence of wind forcing. Farrell and her team have also detected melt ponds on multi-year sea ice in June 2019, at the onset of the annual summer melt period.
Although the ICESat-2 mission is still in its infancy, planning for the next generation of polar altimeters is already underway. Farrell also serves as a member of Europe’s Copernicus Polar Ice and Snow Topography Altimeter (“CRISTAL”) mission advisory group. The advisory group met recently to establish the measurement requirements for a dual-band radar altimeter that will be flown on CRISTAL. The altimeter will provide critical sea ice thickness and land ice elevation measurements, continuing the observational time-series established with ICESat, CryoSat-2, and now ICESat-2. CRISTAL is a Copernicus high-priority candidate mission currently under consideration for further development and launch. If successfully selected, it will likely be launched in the mid-2020s, to provide continuity in our remote sensing capabilities of Earth’s polar regions.
Image credit: NASA Goddard Space Flight Center