Spaceborne thermal infrared observations of Arctic sea ice leads at 30 m resolution

Abstract. Sea ice leads are elongated fractures within sea ice cover, playing an important role in the heat exchange from the ocean to the overlying atmosphere. Narrow leads less than a hundred meters in width contribute considerable heat fluxes, requiring fine-scale observation of Arctic leads. With the launch of Sustainable Development Science Satellite 1 (SDGSAT-1) by China on 5 November 2021, the on-board Thermal Infrared Spectrometer (TIS) provides thermal infrared imagery at an unprecedented resolution of 30 m in a swath of 300 km. We propose a method adapted to the TIS high-resolution infrared images for lead detection in the Arctic. For the first time, the spatial resolution of leads by infrared remote sensing increases from the scale of kilometers to tens of meters. For the Beaufort Sea cases in April 2022, the detection is consistent with the Sentinel-2 visible images, yielding an overall accuracy of 96.30 %. Compared with the Moderate-Resolution Imaging Spectroradiometer (MODIS), the TIS presents more leads with width less hundreds of meters than the results based on the MODIS data. For the three infrared bands of the TIS, the B2 (10.3–11.3 µm) and B3 (11.5–12.5 µm) bands, show similar performances in detecting leads. The B1 band (8.0–10.5 µm) can be complementary to the other two bands, as the temperature measurement sensitivity is different from the other two, benefiting better detection by combining the three bands. This study demonstrates that SDGSAT-1 TIS data at 30 m resolution is well applicable for observing previously unresolvable ice leads, and will provide insight into the contribution of narrow leads to rapid sea ice changes in the Arctic.