Performance Assessment of ICESat-2 Laser Altimeter Data for Water-Level Measurement over Lakes and Reservoirs in China

Abstract

Although the Advanced Topographic Laser Altimeter System (ATLAS) onboard the Ice, Cloud, and Land Elevation Satellite-2 (ICESat-2) was primarily designed for glacier and sea-ice measurement, it can also be applied to monitor lake surface height (LSH). However, its performance in monitoring lakes/reservoirs has rarely been assessed. Here, we report an accuracy evaluation of the ICESat-2 laser altimetry data over 30 reservoirs in China using gauge data. To show its characteristics in large-scale lake monitoring, we also applied an advanced radar altimeter SARAL (Satellite for ARgos and ALtika) and the first laser altimeter ICESat (Ice, Cloud and land Elevation Satellite) to investigate all lakes and reservoirs (>10 km2) in China. We found that the ICESat-2 has a greatly improved altimetric capability, and the relative altimetric error was 0.06 m, while the relative altimetric error was 0.25 m for SARAL. Compared with SARAL and ICESat data, ICESat-2 data had the lowest measurement uncertainty (the standard deviation of along-track heights; 0.02 m vs. 0.17 m and 0.07 m), the greatest temporal frequency (3.43 vs. 1.35 and 1.48 times per year), and the second greatest lake coverage (636 vs. 814 and 311 lakes). The precise LSH profiles derived from the ICESat-2 data showed that most lakes (90% of 636 lakes) had a quasi-horizontal LSH profile (measurement uncertainty <0.05 m), and special methods are needed for mountainous lakes or shallow lakes to extract precise LSHs.

Validation of ICESat-2 Surface Water Level Product ATL13 with Near Real Time Gauge Data

“…In general, the results obtained from this investigation are similar to that of works done by Zhang et al and Yuan et al [6,7]. However the analysis carried out in our study using 15 reservoirs/water bodies, it appears that height retrieved from the strong beam is slightly better than that of height retrieved from the weak beams.…”

“…Zhang et al used ICESat-2 ATL13 data for observing lake level and volume changes in Tibetan Plateau (where human activities are negligible) and concluded that the water surface height from ATL13 is in excellent agreement with in situ measurements for Qinghai Lake where the uncertainty is < 0.2 m [6]. Yuan et al have assessed the ICESat-2 ATL13 data product's accuracy in 30 reservoirs in China and their observation of mean relative errors was 0.06 m [7].…”

Continuous Estimates of Glacier Mass Balance in High Mountain Asia Based on ICESat‐1,2 and GRACE/GRACE Follow‐On Data

“…The root‐mean‐square error was 0.1 m, and 2 cm altimetric accuracy for one along‐track of ICESat‐2 for December 2018 (Zhang et al., 2019). ICESat‐2 also showed better agreement with in situ measurements for over 30 reservoirs in China (∼2 cm) than those of ICESat‐1 (∼7 cm) (Yuan et al., 2020). Over the ice sheet interior, the accuracy of ATL06 was better than 3 cm and the precision of surface measurements was better than 9 cm.…”

An Assessment of Regional ICESat‐2 Sea‐Level Trends

“…For example, Klotz et al., (2020) map individual waves along the ICESat‐2 track and infer wave spectra and wind speed. Others have explored wave detection in sea ice (Horvat et al., 2020), inland water monitoring (Ryan et al., 2020; Yuan et al., 2020), and bathymetry detection (Albright & Glennie, 2020; Armon et al., 2020). By demonstrating general agreement between independent data sources (Figure 1), our analysis indicates an important role for ICESat‐2 in observing ongoing sea‐level change.…”