小卫星监测沿海和内陆水域水生生态系统：HiSea-II 的经验和体会

海丝二号（HiSea-II）于2021年6月11日发射入轨，是首颗同时满足高空间分辨率（20 m）、高信噪比（SNR~300）和宽幅（~200 公里）的小卫星，旨在监测沿海-内陆水体光学及生态参数。得益于海丝二号的高空间分辨率和高信噪比，近岸水体多变的特性和丰富的细节被其轻易捕捉到。

图1（a）展示了其拍摄到的黄海浒苔，通过海丝二号20米的空间分辨率，我们可以更准确地计算其分布面积；（b）展示了在径流输入和再悬浮泥沙的作用下，墨西哥湾内复杂和多变的水质状况；（c）展示了大堡礁及其邻近海域丰富多变的水质和底质情况。除了传统的水色研究，海丝二号也展现出与其空间分辨率相适应的涡旋捕捉探测能力，如图（d）所示。

图1 中国、墨西哥和澳大利亚上空拍摄的四幅 HiSea-II RGB（R：680 nm，G：570 nm，B：490 nm）图像。(a) 2021 年 6 月 22 日，中国黄海浒苔的成片分布。(b) 2023 年 2 月 15 日，墨西哥卡门市附近近海水域的不同水质。(c) 2023 年 3 月 31 日，澳大利亚大堡礁的部分珊瑚礁。(d) 2023 年 1 月 30 日，北部湾，船体航行导致的对称卡门涡街。

海洋水色小卫星目前还处于早期阶段，我们呼吁加大投入和努力来推进这一新平台的发展，以期在未来建立海洋水色小卫星星座，以有效监测沿海-内陆水生生态系统。

原文链接：https://ieeexplore.ieee.org/document/10680072/authors#authors

Lee Z , Wang D , Zheng Z ,et al. SmallSat for Monitoring Aquatic Ecosystem of Coastal and Inland Waters: The Experience of HiSea-II.IEEE Transactions on Geoscience and Remote Sensing, 62, 1-10. DOI:10.1109/TGRS.2024.3459912.

SmallSat for Monitoring Aquatic Ecosystem of Coastal and Inland Waters: The Experience of HiSea-II

HiSea-II, designed for monitoring coastal–inland biogeochemical properties and launched into orbit on June 11, 2021, is the first small satellite (SmallSat) simultaneously satisfying high spatial resolution (20 m), high signal-to-noise ratio (SNR) (∼300) and wide swath (∼200 km). Since HiSea-II has a spatial resolution at 20 m and an SNR of ∼300 in the visible bands, many detailed features of nearshore waters are well captured and illustrated.

Fig. 1(a) shows the patchy distribution of Ulva prolifera in the Yellow Sea thanks to the high spatial resolution, which helps to calculate more accurately the area covered by Ulva prolifera. Image of Fig. 1(b) over offshore waters of Mexico, shows complex and variable water colors that indicate wide variations of water quality in this area caused by outflow and resuspension of sediments. Fig. 1(c) demonstrates the rich and varying water and bottom properties associated with the Great Barrier Reef’s coral reefs and adjacent nearshore waters. In addition to the conventional observation of ocean color, in Fig. 1(d) the presence of the Carmen vortex at the stern due to flow instability suggests that the HiSea-II ocean-color sensor can also be applied to the detection and study of the vortex and fine-scale eddies.

Fig. 1. Four HiSea-II RGB (R: 680 nm, G: 570 nm, and B: 490 nm) images over China, USA, and Australia. (a) Patchy distribution of Ulva prolifera in the Yellow Sea, China, June 22, 2021. (b) Varying water quality of offshore waters near Carmen City, Mexico, February 15, 2023. (c) Part of the Great Barrier Reef’s coral reefs, Australia, March 31, 2023. (d) Carmen vortex with symmetrical shedding of a ship’s trails in the Beibu Gulf, January 30, 2023.

SmallSat for ocean color is at its early stage, we advocate more investment and efforts to advance this useful platform, so a constellation of ocean-color SmallSats could be established in the future for effective monitoring of coastal–inland aquatic ecosystems.