ICESAT-2 ALTIMETRY AS GEODETIC CONTROL

Abstract. Digital elevation models (DEMs) are of fundamental importance for a large variety of scientific and commercial applications. Many geoscience studies require the most precise and current information about the Earth’s topography. Independent quality assessments of these DEMs are crucial to their appropriate use in land process studies, as inputs to models, and for detection of topographic change. The Ice, Cloud and land Elevation Satellite (ICESat) provided globally-distributed elevation data of high accuracy that demonstrated to be well-suited for evaluating continental DEMs after appropriate editing (Carabajal and Harding, 2005; Carabajal and Harding, 2006; Carabajal et al., 2010 and 2011; Carabajal and Boy, 2016). ICESat-2, launched on September 15th, 2018, provides an opportunity to develop a dataset suitable for Geodetic Ground Control. With increased coverage, ICESat-2/ATLAS features 6 laser beams with 532 nm wavelength, using photon counting technologies. With a nearly polar orbit, altimetry from ICESat-2 is available for latitudes reaching up to 88 degrees, on a 91-day repeat orbit with monthly sub-cycles. ICESat-2’s footprint size is ∼17 m, at 10 kHz pulse repetition frequency, or 0.75 m along track. Its pointing control is 45 m, with a pointing knowledge of 6.5 m, and a single photon precision of 800 ps. Sophisticated data processing techniques on the ground, optimized by surface type, produce high quality estimates of topography. We illustrate the use of ICESat-2 altimetry to assess DEM’s accuracy using ATL08 release 002 elevations (Land and Vegetation) products (Neuenschwander and Pitts, 2019), showing comparable results to those using ICESat-derived Geodetic Ground Control.