The Performance of ICESat-2's Strong and Weak Beams in Estimating Ground Elevation and Forest Height
Xiaoxiao Zhu, Sheng Nie, Cheng Wang, Xiaohuan Xi
Abstract
The Ice, Cloud and Land Elevation Satellite-2 (ICESat-2) mission provides effective data for measuring global ground elevation and forest height. Unlike the ICESat, ICESat-2 emits three pairs of beams. Each pair includes a strong beam and a weak beam with an energy ratio of 4:1. To evaluate the performance of ICESat-2's strong and weak beams in estimating ground elevation and forest height, the ICESat-2 data in four different scenarios were analyzed; 1) ICESat-2's strong beams in the daytime, 2) ICESat-2's weak beams in the daytime, 3) ICESat-2's strong beams in the nighttime, and 4) ICESat-2's weak beams in the nighttime. The results indicate that the weak beams perform as well as strong beams in estimating ground elevations due to high coefficient of determination (R <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ) values and low root-mean-squared error (RMSE) values regardless of the daytime and nighttime data. While for forest height estimation, ICESat-2's weak beams perform worse than strong beams and the daytime data perform worse than the nighttime data. These results suggest that all ICESat-2 data are suitable for ground elevation extraction, while the ICESat-2's weak beams in the daytime are not suited to estimate forest height.