We present the results of an assessment of ice surface elevation measurements from NASA's Ice, Cloud, and land Elevation Satellite-2 (ICESat-2) along the CHINARE (CHINese Antarctic Research Expedition) route near the Amery Ice Shelf in East Antarctica. The validation campaign was designed and implemented in cooperation with the 36th CHINARE Antarctic expedition from December 2019 to February 2020. The assessment of the ICESat-2 geolocated photon product (ATL03) and land ice elevation product (ATL06) was performed based on coordinated multi-sensor observations using two roof-mounted kinematic global navigation satellite system (GNSS) receivers, two line arrays of corner cube retroreflectors (CCRs), two sets of retroreflective target sheets (RTSs), and two unmanned aerial vehicles (UAVs) with cameras. This systematic validation of the ICESat-2 data covered a variety of Antarctic ice surface conditions along the 520 km traverse from the coastal Zhongshan Station to the inland Taishan Station. This comprehensive investigation is complementary to the 750 km traverse validation of flat inland Antarctica containing a 300 km latitude traverse of 88^∘ S by the mission team (Brunt et al., 2021). Overall, the validation results show that the elevation of the ATL06 ice surface points is accurate to 1.5 cm with a precision of 9.1 cm along the 520 km CHINARE route. The elevation of the ATL03 photons has an offset of 2.1 cm from a GNSS-surveyed CCR and is accurate to 2.5 cm with a precision of 2.7 cm as estimated by using RTSs. The validation results demonstrate that the estimated ICESat-2 elevations are accurate to 1.5–2.5 cm in this East Antarctic region, which shows the potential of the data products for eliminating mission biases by overcoming the uncertainties in the estimation of mass balance in East Antarctica. It should be emphasized that the results based on the CCR and RTS techniques can be improved by further aggregation of observation opportunities for a more robust assessment. The developed validation methodology and sensor system can be applied for continuous assessment of ICESat-2 data, especially for calibration against potential degradation of the elevation measurements during the later operation period.

The Ice, Cloud, and Land Elevation Satellite-2 (ICESat-2), equipped with the Advanced Topographic Laser Altimetry System (ATLAS), enhances ice surface elevation change estimations. ATLAS significantly improves elevation accuracy from over 10 cm, as seen in ICESat’s full-waveform technique, to 2–4 cm. ICESat-2 data’s elevation quality is currently validated at the single-pulse level using the corner cube retroreflector (CCR) method, a terrain-independent technique insensitive to ice surface conditions. This study introduces a cost-effective CCR system for validating ICESat-2 elevation data from Antarctica’s firn surface, complementing the ICESat-2 Science Team’s approach. Through three validation campaigns in Antarctica and Shanghai, China, we enhanced our CCR system in design of the prism hardware, alignment of the CCR array, and determination of valid photon data. We implemented a self-adaptive window determination strategy for valid CCR-returned signal photons to minimize the impact of inadequately returned photons from the Fraunhofer diffraction pattern’s lobes and two closely elevated CCRs. The accurate elevations of single pulses from each CCR were determined and analyzed using global navigation satellite systems (GNSSs) in situ observations during the ICESat-2 overpasses in 2020–2022. Our refined CCR validation system shows that ICESat-2’s pulse elevation has a bias of less than 3.0 cm and a precision of ±1.7 cm in the latest experiment on the Nansen ice shelf, East Antarctica.

Modelling of glacier and ice sheet micro-topography is meaningful for the understanding of interactions between local ice mass and climate. Here, we used an Unmanned Aerial Vehicle (UAV) platform composed of a DJI Phantom 4 and a D-RTK mobile station to model the surface micro-topography around Zhongshan Station of China, East Antarctica. Two UAV survey types (vertical and oblique aerial photogrammetry) were performed during the China's 35th Antarctic expedition (CHINARE) in 2018–2019. Six surveys were obtained by the SfM-MVS technology. Then, we extracted the features of glacier surface micro-topography (blue ice, crevasses, ice doline and melt-water). It’s noteworthy that traces of melt-water and a large ice doline appeared on the surface of Dalk Glacier in December 2018. Finally, we concluded that surface micro-topographic features, observable in the UAV-derived models but unavailable on satellite images, may reveal hints for interactions between surface and beneath processes in regional polar glacier.

Ice, Cloud, and land Elevation Satellite-2 (ICESat-2) carries a photon-counting laser altimeter with an unprecedented elevation accuracy of 2–4 cm. Since its data availability in 2018, there has been a challenge for the establishment of a new data processing model that can take advantage of this satellite for accurately estimating volumetric changes in Antarctica and associated contribution to global sea level rise (GSLR). We introduce an innovative multitemporal elevation change estimation model (MECEM) that separates precipitation effects from topographic influences to eliminate their correlations and estimates the elevation change rates effectively through a spatiotemporal iterative procedure. The MECEM results are validated by using GNSS in situ observations, snow stakes measurements, and airborne altimetric survey data. The results are also compared with those from ICESat and ESA multimission radar altimetric dataset. It is demonstrated that the model is capable of estimating small thickening of $1.8~\pm ~0.1$ cm yr1 in the Vostok subglacial lake region. Using ICESat-2 ATL06 data from 2019 to 2023, the model is proven to be effective in the estimation of elevation change rates in Antarctic basins of different characteristics. Our results show that an increase of $0.103~\pm ~0.001$ m yr1 in thickening is found from 2017–2021 to 2019–2023 in Dronning Maud Land. Furthermore, an accelerated thinning by $- 0.12~\pm ~0.035$ m yr1 is witnessed from 2003–2019 to 2019–2023 in the fast-flowing Pine Island Glacial. With more ICESat-2 data acquired, the developed MECEM model can be applied for estimating the contribution of the entire Antarctic ice sheet (AIS) to GSLR.

Modelling of ice sheet micro-topography based on Unmanned Aerial Vehicle (UAV) is meaningful for the understanding of interactions between local ice mass and climate. 3D reconstruction based on UAV has advantages that satellite remote sensing cannot replace. Here, the surface micro-topography measurement was performed during the China's 36th Antarctic expedition (CHINARE) in 2019–2020, using an UAV platform composed of a DJI Phantom 4 and a D-RTK GNSS mobile station around Zhongshan Station of China. Then, four partly overlapped models were obtained by the SfM-MVS technology. Affected by the complex environment factors, the performance of this technology sometimes is challenged over the marginal Antarctic Ice Sheet. Satellite altimetry is one of the most essential technologies for land ice surface elevation measurements, widely used in regional or global ice mass balance estimations.We use the land ice surface heights with high accuracy derived from the Ice, Cloud, and Land Elevation Satellite-2 (ICESat-2) to compare with the UAV-derived models. Combined with the high precision and space-time resolution of ICESat-2 satellite altimetry, the results of the model were evaluated under different terrain conditions. It has been certified that the derived models without extra GCPs were capable of detecting the surface micro-topographic features if considering the potential factors, which can be popularized and developed in polar research.

This paper presents the results of the assessment of ICESat-2 ice surface elevations along the CHINARE (CHINese Antarctic Research Expedition) route in East Antarctica. The validation campaign was designed and implemented in cooperation with the 36^th CHINARE Antarctic expedition from December 2019 to February 2020. The assessment of the ICESat-2 ATL03 and ATL06 data was performed based on coordinated multi-sensor observations using two roof-mounted kinematic GNSS receivers, two line arrays of corner cube retroreflectors (CCRs), two sets of retroreflective target sheets (RTSs), and two unmanned aerial vehicles (UAVs) with cameras. This systematic validation of the ICESat-2 data covered a variety of Antarctic ice surface conditions along the 520 km traverse from the coastal Zhongshan Station to the inland Taishan Station. This comprehensive investigation is complementary to the 750 km traverse validation of flat inland Antarctica containing a 300 km latitude traverse of 88° S by the mission team in a previous study. Overall, the validation results show that the elevation of the ATL06 ice surface points is accurate to 1.1 cm with a precision of 9.7 cm along the 520 km CHINARE route. The elevation of the ATL03 photons has an offset of 2.4 cm from a GNSS-surveyed CCR, and is accurate to 2.5 cm with a precision of 2.7 cm as estimated by using RTSs. The validation results demonstrate that the estimated ICESat-2 elevations are accurate to 1.1–2.5 cm in this East Antarctic region, which is important for overcoming the uncertainties in the estimation of mass balance in East Antarctica. The developed validation methodology and sensor system can be improved for continuous assessment of ICESat-2 data, especially during the later operation period.