Ocean Remote Sensing Using Spaceborne GNSS-Reflectometry: A Review

Spaceborne global navigation satellite system reflectometry (GNSS-R) is an emerging remote sensing technology that utilizes Earth surface reflections of GNSS signals to monitor geophysical parameters. With its unique advantages of high spatiotemporal resolution, low observational cost, wide coverage, and all-weather operation, GNSS-R has found extensive applications in ocean remote sensing. Recent successful launches of spaceborne GNSS-R platforms, such as TechDemoSat-1 in 2014, Cyclone GNSS in 2016, BuFeng-1 A/B in 2019, and FengYun-3E in 2021, have opened up new opportunities in this field. This article provides a comprehensive overview of the latest advancements in the application of spaceborne GNSS-R in ocean remote sensing. It covers satellite missions related to spaceborne GNSS-R and explores various methods and techniques for ocean remote sensing applications, including sea surface wind mapping, hurricanes, typhoons, and tropical cyclones monitoring, tsunamis and storm surges detection, sea surface altimetry and wave height measurement, sea ice sensing, and rainfall estimation, among others. Furthermore, the article discusses the challenges, prospects, and future outlook of spaceborne GNSS-R.