Abstract Operated since the end of 2009, the European Space Agency (ESA) Soil Moisture and Ocean Salinity (SMOS) satellite mission is the first orbiting radiometer that collects regular and global observations from space of two Essential Climate Variables of the Global Climate Observing System: Sea Surface Salinity (SSS) and Soil Moisture. The National Aeronautics and Space Administration (NASA) Aquarius mission, with the primary objective to provide global SSS measurements from space operated from mid-2011 to mid-2015. NASA's Soil Moisture Active-Passive (SMAP) mission, primarily dedicated to soil moisture measurements, but also monitoring SSS, has been operating since early 2015. The primary sensors onboard these three missions are passive microwave radiometers operating at 1.4 GHz (L-band). SSS is retrieved from radiometer measurements of the sea surface brightness temperature (TB). In this paper, we first provide a historical review of SSS remote sensing with passive L-band radiometry beginning with the discussions of measurement principles, technology, sensing characteristics and complementarities of the three aforementioned missions. The assessment of satellite SSS products is then presented in terms of individual mission characteristics, common algorithms, and measurement uncertainties, including the validation versus in situ data, and, the consideration of sampling differences between satellite SSS and in situ salinity measurements. We next review the major scientific achievements of the combined first 10 years of satellite SSS data, including the insights enabled by these measurements regarding the linkages of SSS with the global water cycle, climate variability, and ocean biochemistry. We also highlight the new ability provided by satellites to monitor mesoscale and synoptic-scale SSS features and to advance our understanding of SSS' role in air-sea interactions, constraining ocean models, and improving seasonal predictions. An overview of satellite SSS observation highlights during this first decade and upcoming challenges are then presented.

中文翻译：

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来自星载 L 波段辐射计的海面盐度估计：第一个十年观测概述（2010-2019）

摘要 欧洲航天局 (ESA) 土壤水分和海洋盐度 (SMOS) 卫星任务自 2009 年底开始运行，是第一个从空间收集全球气候观测系统两个基本气候变量的定期和全球观测的轨道辐射计：海面盐度 (SSS) 和土壤水分。美国国家航空航天局 (NASA) Aquarius 任务，主要目标是从 2011 年年中至 2015 年年中运营的太空提供全球 SSS 测量值。NASA 的土壤湿度主动-被动 (SMAP) 任务主要致力于土壤湿度测量，但也监测 SSS，自 2015 年初开始运行。这三个任务上的主要传感器是工作在 1.4 GHz（L 波段）的无源微波辐射计. SSS 是从海面亮度温度 (TB) 的辐射计测量值中获取的。在本文中，我们首先对采用无源 L 波段辐射测量的 SSS 遥感进行了历史回顾，首先讨论了上述三个任务的测量原理、技术、传感特性和互补性。然后根据单个任务特征、通用算法和测量不确定性，包括验证与原位数据，以及卫星 SSS 和原位盐度测量之间的采样差异的考虑，对卫星 SSS 产品进行评估。接下来我们回顾一下前 10 年卫星 SSS 数据合并的主要科学成果，包括通过这些测量获得的关于 SSS 与全球水循环、气候变异和海洋生物化学之间联系的见解。我们还强调了卫星提供的监测中尺度和天气尺度 SSS 特征的新能力，并增进我们对 SSS 在海气相互作用、约束海洋模型和改进季节预测中的作用的理解。然后概述了这第一个十年中卫星 SSS 观测的亮点和即将到来的挑战。