Retrieval of Antarctic sea ice freeboard and thickness from HY-2B satellite altimeter data

• Published in: Acta oceanologica Sinica 2024-03, Vol.43 (3), p.87-101
• Main Authors: Chen, Yizhuo, Pang, Xiaoping, Ji, Qing, Yan, Zhongnan, Liang, Zeyu, Zhang, Chenlei
• Format: Article
• Language: English
• Subjects: Aeronautics; Algorithms; Altimeters; Altimetry; Antarctic sea ice; Classification; Climate change; Climatology; Decision trees; Earth and Environmental Science; Earth Sciences; Ecology; Engineering Fluid Dynamics; Environmental Chemistry; Equilibrium equations; Freeboard; Global climate; Ice cover; Ice thickness; Marine & Freshwater Sciences; Oceanography; Polar waters; Radar; Radar altimeters; Radar altimetry; Radar data; Radar imaging; Radar satellites; Radio altimeters; Remote observing; Remote sensing; SAR (radar); Satellite altimetry; Satellites; Sea ice; Sea ice thickness; Sea surface; Spectroradiometers; Static equilibrium; Surface temperature; Synthetic aperture radar; Thickness; Time series
• ISSN: 0253-505X; 1869-1099
• DOI: 10.1007/s13131-023-2250-2

Antarctic sea ice is an important part of the Earth’s atmospheric system, and satellite remote sensing is an important technology for observing Antarctic sea ice. Whether Chinese Haiyang-2B (HY-2B) satellite altimeter data could be used to estimate sea ice freeboard and provide alternative Antarctic sea ice thickness information with a high precision and long time series, as other radar altimetry satellites can, needs further investigation. This paper proposed an algorithm to discriminate leads and then retrieve sea ice freeboard and thickness from HY-2B radar altimeter data. We first collected the Moderate-resolution Imaging Spectroradiometer ice surface temperature (IST) product from the National Aeronautics and Space Administration to extract leads from the Antarctic waters and verified their accuracy through Sentinel-1 Synthetic Aperture Radar images. Second, a surface classification decision tree was generated for HY-2B satellite altimeter measurements of the Antarctic waters to extract leads and calculate local sea surface heights. We then estimated the Antarctic sea ice freeboard and thickness based on local sea surface heights and the static equilibrium equation. Finally, the retrieved HY-2B Antarctic sea ice thickness was compared with the CryoSat-2 sea ice thickness and the Antarctic Sea Ice Processes and Climate (ASPeCt) ship-based observed sea ice thickness. The results indicate that our classification decision tree constructed for HY-2B satellite altimeter measurements was reasonable, and the root mean square error of the obtained sea ice thickness compared to the ship measurements was 0.62 m. The proposed sea ice thickness algorithm for the HY-2B radar satellite fills a gap in this application domain for the HY-series satellites and can be a complement to existing Antarctic sea ice thickness products; this algorithm could provide long-time-series and large-scale sea ice thickness data that contribute to research on global climate change.