A Framework for Evaluating and Improving the Geolocation Capability of ICESat-2 Photon Data Using AAV Surveys in Antarctic Marginal Regions

The laser altimetry data acquired from the Ice, Cloud, and Land Elevation Satellite-2 (ICESat-2) are instrumental in monitoring the Antarctic ice sheet (AIS) and glaciers. Its land ice elevation product (ATL06) has demonstrated an impressive elevation accuracy of 2–4 cm over flat inland ice areas. However, under the complex and extreme conditions of ice sheet marginal regions, a more comprehensive understanding of ICESat-2’s geolocation capability is crucial. Such insights are essential for enhancing the satellite’s ability to accurately quantify dynamic changes in Antarctic glaciers and marginal zones, thereby supporting precise regional mass balance estimations. During the 36th Chinese National Antarctic Research Expedition (CHINARE) in 2019–2020, high-precision autonomous aerial vehicle (AAV) surveys supported by the Global Navigation Satellite Systems (GNSS) were conducted near ICESat-2 overpass times to systematically evaluate and improve ICESat-2’s geolocation capability in Antarctic marginal regions. Our analysis revealed that the ATL06 data’s native 20-m resolution often lacks the granularity to resolve fine topographic features in these areas. ICESat-2 photon data (ATL03), however, hold the potential for more accurate elevation estimations, particularly in the photon-counting mode on complex ice surfaces. To address this, we propose a framework for evaluating and improving ICESat-2 photon data geolocation capability based on high-precision AAV digital surface model (DSM) registration. This framework uses a “photon cloud” profile fitting method on ATL03 photon data, enhancing the elevation profile by selectively filtering noise and applying adaptive polynomial fitting. Geolocation performance of the resulting high-resolution (0.7 m) ICESat-2 elevation profiles was evaluated by analyzing discrepancies between ICESat-2 profiles and AAV DSM data, considering geolocation error, terrain slope, and curvature, along the ice sheet margin near Zhongshan Station, East Antarctica. Geolocation offsets for ICESat-2 range from 2.20 to 5.40 m. Our results demonstrate that the proposed framework improves the ICESat-2 photon data’s ability to monitor dynamic ice features and surface elevation changes in Antarctic marginal regions.