Abstract Spaceborne radars offer a unique three‐dimensional view of the atmospheric components of the Earth's hydrological cycle. Existing and planned spaceborne radar missions provide cloud and precipitation information over the oceans and land difficult to access in remote areas. A careful look into their measurement capabilities indicates considerable gaps that hinder our ability to detect and probe key cloud and precipitation processes. The international community is currently debating how the next generation of spaceborne radars shall enhance current capabilities and address remaining gaps. Part of the discussion is focused on how to best take advantage of recent advancements in radar and space platform technologies while addressing outstanding limitations. First, the observing capabilities and measurement highlights of existing and planned spaceborne radar missions including TRMM, CloudSat, GPM, RainCube, and EarthCARE are reviewed. Then, the limitations of current spaceborne observing systems, with respect to observations of low‐level clouds, midlatitude and high‐latitude precipitation, and convective motions, are thoroughly analyzed. Finally, the review proposes potential solutions and future research avenues to be explored. Promising paths forward include collecting observations across a gamut of frequency bands tailored to specific scientific objectives, collecting observations using mixtures of pulse lengths to overcome trade‐offs in sensitivity and resolution, and flying constellations of miniaturized radars to capture rapidly evolving weather phenomena. This work aims to increase the awareness about existing limitations and gaps in spaceborne radar measurements and to increase the level of engagement of the international community in the discussions for the next generation of spaceborne radar systems.

中文翻译：

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星载云和降水雷达：现状、挑战和前进方向

摘要 星载雷达提供了地球水文循环大气成分的独特三维视图。现有和计划中的星载雷达任务可提供偏远地区难以进入的海洋和陆地上空的云和降水信息。仔细研究它们的测量能力表明存在相当大的差距，这些差距阻碍了我们检测和探测关键云和降水过程的能力。国际社会目前正在讨论下一代星载雷达如何增强当前能力并解决剩余差距。部分讨论集中在如何最好地利用雷达和空间平台技术的最新进展，同时解决突出的局限性。第一的，审查了现有和计划中的星载雷达任务的观测能力和测量亮点，包括 TRMM、CloudSat、GPM、RainCube 和 EarthCARE。然后，深入分析了当前星载观测系统在低层云、中纬度和高纬度降水以及对流运动观测方面的局限性。最后，该评论提出了潜在的解决方案和未来有待探索的研究途径。有希望的前进路径包括收集针对特定科学目标量身定制的整个频段的观测，使用混合脉冲长度收集观测以克服灵敏度和分辨率之间的权衡，以及飞行小型化雷达星座以捕捉快速变化的天气现象。