Land ice height-retrieval algorithm for NASA's ICESat-2 photon-counting laser altimeter

Abstract

The Ice, Cloud, and land Elevation Satellite-2 (ICESat-2) and its sole scientific instrument, the Advanced Topographic Laser Altimeter System (ATLAS), was launched on 15 September 2018 with a primary goal of measuring changes in the surface of the Earth's land ice (glaciers and ice sheets). ATLAS is a photon-counting laser altimeter, which records the transit time of individual photons in order to reconstruct surface height along track. The ground-track pattern repeats every 91 days such that changes in ice sheet surface height can be estimated through time. In this paper, we describe the set of algorithms that have been developed for ICESat-2 to retrieve ice sheet surface height from the geolocated photons for the Land Ice Along-Track Height Product (ATL06), and demonstrate their output and performance using a synthetic dataset over various land-ice surfaces and under different cloud conditions. We show that the ATL06 algorithm is expected to perform at the level required to meet the ICESat-2 science objectives for land ice.

Temporal and spatial variability in surface roughness and accumulation rate around 88° S from repeat airborne geophysical surveys

“…The surface roughness of polar ice sheets is primarily a result of ice dynamics and surface-atmosphere interactions on varying temporal and spatial scales. In general, ice flow over rugged bedrock topography causes roughness features that can extend from several hundreds of kilometers to a few kilometers depending on ice thickness, flow speed, and basal conditions (e.g., Smith et al, 2006, and references therein). These large-scale variations in ice surface topography caused by ice dynamics are not the topic of this analysis.…”

A Framework for Correcting Ionospheric Artifacts and Atmospheric Effects to Generate High Accuracy InSAR DEM

“…Hence, to eliminate the influence of single reference data on the validation results, high-precision altimetry data points from Ice, Cloud, and and Elevation Satellite-2 or ICESat-2 were adopted to further verify the accuracy of the derived DEM. These data are accurate enough to be used as ground control points (GCPs) for assessing the InSAR DEMs [24][25][26][27]. The blue dots in Figure 2 (3784 GCPs) and Figure 7 (7269 GCPs) are the ATL08 land data products collected by ICESat-2.…”

Mapping the Antarctic Grounding Zone from ICESat-2 Laser Altimetry

“…The ATL06 elevation measurements are derived from the individual photon elevation observations, averaged over a 40 m length segment. The segments overlap by 50% along each of the six ground tracks, thus the ATL06 elevation measurements are separated by 20 m along each ground track (Smith et al 2019). Five cycles exist during the study period but only cycles 3, 4 and 5 are exact repeat cycles.…”