Impact of Slopes on ICESat-2 Elevation Accuracy Along the CHINARE Route in East Antarctica

As the follow-on study to the assessment of ICESat-2 ice surface elevations, we assessed how they are influenced by the surface slopes, which are derived from the ICESat-2 elevations of the received photons and available in the land-ice surface heights product (ATL06), by using coordinated GNSS observations along a 520 km long traverse of the 36th CHINese Antarctic Research Expedition (CHINARE) route in East Antarctica. We further analyzed the impact of the slopes on the ICESat-2 elevation accuracy, which is important for the studies of the local ice flow dynamics, mass balance, and Antarctic contribution to sea level rise. We found that the along-track surface slopes in the ICESat-2 ATL06 data have a high overall agreement of 0.18° ± 0.16° (1σ) and a correlation of 0.66 (R2) with the GNSS slopes. Furthermore, two waveform related corrections, first-photon, and transmit-pulse shape bias corrections, were able to adjust on average a combined elevation bias of ∼1.0 cm. Finally, we found a high linear dependency of elevation errors on slopes, i.e., ∼6.2 cm per 1° slope (R2 = 0.57, slope <0.7°). Although significantly smaller than those in ICESat elevation data, these slope-induced elevation errors in ICESat-2 ATL06 data should be carefully considered for studies using high precision elevations, such as the mass balance estimation in sloped areas in Antarctica