Assessment of ICESat-2 ice surface elevations over the Chinese Antarctic Research Expedition (CHINARE) route, East Antarctica, based on coordinated multi-sensor observations

Abstract

Abstract. 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.

Assessment of CryoSat-2 Baseline-D Height Product by GNSS and ICESat-2 in Lambert-Amery System, East Antarctica

“…Five GNSS base stations spaced at ~100 km intervals are post-processed by using the precise point positioning (PPP) technique, which is implemented in the multi-frequency and multi-system instantaneous PPP (MUSIP) [24], and achieve an internal height accuracy on the subcentimeter scale [13]. The GNSS solutions along the traverse are given by the technique of the post-processed kinematic (PPK), which is implemented in the RTKLIB (V2.4.3) [25,26] (http://www.rtklib.com/), and achieve an internal height accuracy of 1.6 ± 0.6 cm [13]. Also, the external height accuracy of the traverse GNSS (N=625,358) is evaluated to be 0.3 ± 5.8 cm based on traverse crossovers (N=26) [13].…”

“…The GNSS solutions along the traverse are given by the technique of the post-processed kinematic (PPK), which is implemented in the RTKLIB (V2.4.3) [25,26] (http://www.rtklib.com/), and achieve an internal height accuracy of 1.6 ± 0.6 cm [13]. Also, the external height accuracy of the traverse GNSS (N=625,358) is evaluated to be 0.3 ± 5.8 cm based on traverse crossovers (N=26) [13]. The GNSS geographic coordinates, including latitude and longitude, are referenced to the WGS84 ellipsoid [7,8,13].…”

“…Also, the external height accuracy of the traverse GNSS (N=625,358) is evaluated to be 0.3 ± 5.8 cm based on traverse crossovers (N=26) [13]. The GNSS geographic coordinates, including latitude and longitude, are referenced to the WGS84 ellipsoid [7,8,13]. The GNSS heights from the PPP and PPK are based on the ITRF2014 reference frame [13].…”

“…In this paper, we carried out a comprehensive assessment of the up-to-date CS2 BD LRM/SIN height products in the Lambert-Amery system (LAS), East Antarctica. Firstly, our team collected ~1000 km of GNSS survey data in round trips along the 36 th CHINARE traverse between the Taishan Station (TSS) and Zhongshan Station (ZSS) in East Antarctica [13], and we evaluated the absolute accuracy of the CS2 BD SIN height product based on post-processed traverse GNSS coordinates on the snow surface. Secondly, based on the highaccuracy ICESat-2 (referred to as IS2 below) ATL06 height product [8,13], we evaluated the CS2 BD LRM/SIN height products in LAS, East Antarctica.…”

“…Firstly, our team collected ~1000 km of GNSS survey data in round trips along the 36 th CHINARE traverse between the Taishan Station (TSS) and Zhongshan Station (ZSS) in East Antarctica [13], and we evaluated the absolute accuracy of the CS2 BD SIN height product based on post-processed traverse GNSS coordinates on the snow surface. Secondly, based on the highaccuracy ICESat-2 (referred to as IS2 below) ATL06 height product [8,13], we evaluated the CS2 BD LRM/SIN height products in LAS, East Antarctica. Finally, to address the noninstrumental sources of the height differences, we conducted a significance analysis of the univariate linear regression between the height differences and terrain factors (slope/roughness) along the traverse and in LAS, respectively.…”