The National Aeronautics and Space Administration (NASA)’s Operation IceBridge (OIB) was a 13-year (2009–2021) airborne mission to survey land and sea ice across the Arctic, Antarctic, and Alaska. Here, we review OIB’s goals, instruments, campaigns, key scientific results, and implications for future investigations of the cryosphere. OIB’s primary goal was to use airborne laser altimetry to bridge the gap in fine-resolution elevation measurements of ice from space between the conclusion of NASA’s Ice, Cloud, and land Elevation Satellite (ICESat; 2003–2009) and its follow-on, ICESat-2 (launched 2018). Additional scientific requirements were intended to contextualize observed elevation changes using a multisensor suite of radar sounders, gravimeters, magnetometers, and cameras. Using 15 different aircraft, OIB conducted 968 science flights, of which 42% were repeat surveys of land ice, 42% were surveys of previously unmapped terrain across the Greenland and Antarctic ice sheets, Arctic ice caps, and Alaskan glaciers, and 16% were surveys of sea ice. The combination of an expansive instrument suite and breadth of surveys enabled numerous fundamental advances in our understanding of the Earth’s cryosphere. For land ice, OIB dramatically improved knowledge of interannual outlet-glacier variability, ice-sheet, and outlet-glacier thicknesses, snowfall rates on ice sheets, fjord and sub-ice-shelf bathymetry, and ice-sheet hydrology. Unanticipated discoveries included a reliable method for constraining the thickness within difficult-to-sound incised troughs beneath ice sheets, the extent of the firn aquifer within the Greenland Ice Sheet, the vulnerability of many Greenland and Antarctic outlet glaciers to ocean-driven melting at their grounding zones, and the dominance of surface-melt-driven mass loss of Alaskan glaciers. For sea ice, OIB significantly advanced our understanding of spatiotemporal variability in sea ice freeboard and its snow cover, especially through combined analysis of fine-resolution altimetry, visible imagery, and snow radar measurements of the overlying snow thickness. Such analyses led to the unanticipated discovery of an interdecadal decrease in snow thickness on Arctic sea ice and numerous opportunities to validate sea ice freeboards from satellite radar altimetry. While many of its data sets have yet to be fully explored, OIB’s scientific legacy has already demonstrated the value of sustained investment in reliable airborne platforms, airborne instrument development, interagency and international collaboration, and open and rapid data access to advance our understanding of Earth’s remote polar regions and their role in the Earth system.

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美国宇航局冰桥行动的科学遗产

美国国家航空航天局 (NASA) 的冰桥行动 (OIB) 是一项为期 13 年（2009-2021 年）的空中任务，旨在调查北极、南极和阿拉斯加的陆地和海冰。在这里，我们回顾了 OIB 的目标、仪器、活动、关键科学成果以及对未来冰冻圈调查的影响。OIB 的主要目标是使用机载激光测高仪弥合 NASA 冰、云和陆地高程卫星（ICESat；2003-2009）的结论与其后续的 ICESat 之间在太空冰的精细分辨率高程测量方面的差距-2（2018 年推出）。其他科学要求旨在使用由雷达测深仪、重力仪、磁力计和相机组成的多传感器套件将观测到的海拔变化情境化。OIB 使用 15 架不同的飞机进行了 968 次科学飞行，其中 42% 是对陆地冰的重复调查，42% 是对格陵兰和南极冰盖、北极冰盖和阿拉斯加冰川以前未绘制的地形的调查，16% 是对海冰的调查。广泛的仪器套件和广泛的调查相结合，使我们对地球冰冻圈的理解取得了许多根本性的进展。对于陆地冰，OIB 极大地提高了对年际出口冰川变化、冰盖和出口冰川厚度、冰盖降雪率、峡湾和亚冰架水深测量以及冰盖水文学的了解。意料之外的发现包括一种可靠的方法，用于限制冰盖下难以确定的切槽内的厚度、格陵兰冰盖内冷杉含水层的范围、许多格陵兰和南极出口冰川在其接地区易受海洋驱动融化的影响，以及阿拉斯加冰川表面融化驱动的质量损失占主导地位。对于海冰，OIB 显着提高了我们对海冰干舷及其积雪的时空变化的理解，特别是通过对上覆积雪厚度的精细分辨率高度计、可见光图像和积雪雷达测量的组合分析。此类分析导致意外发现北极海冰上积雪厚度的年代际减少，并有许多机会通过卫星雷达高度测量验证海冰干舷。虽然其许多数据集尚未得到充分探索，但 OIB 的科学遗产已经证明了对可靠机载平台进行持续投资的价值，