Abstract Simulated signals from Global Navigation Satellite Systems (GNSS), reflected off the sea surface and received aboard low Earth orbiting satellites, have been used to derive sea surface height (SSH) and assimilated into an ocean model in an Observing System Simulation Experiment (OSSE). The experimental approach is named GNSS Reflectometry (GNSS-R), which was proposed for the International Space Station (ISS). This scientific experiment was conducted in the frame of the ESA mission called “GNSS REflectometry, Radio Occultation and Scatterometry aboard the International Space Station” (GEROS-ISS). In this study, three sources of uncertainties of the planned GNSS-R altimeter are considered by the GNSS-R simulator: the troposphere, the ionosphere, and a noise term. An ensemble optimal interpolation (EnOI) data assimilation system is set up for an eddy-resolving HYbrid Coordinate Ocean Model (HYCOM) of the South China Sea (SCS), and two data assimilation runs are performed from the 18th June to the 31st July 2014 with and without GNSS-R. In the run assimilating GNSS-R, the measurements come in addition to traditional Sea Level Anomalies (SLA) from present-day altimeters. In spite of the lower precision of individual GNSS-R retrievals, the results obtained in July show an overall improvement of the Root Mean Squared Difference (RMSD) by 14%, compared to traditional altimeter data only. Considering the crossing of Typhoon Rammasun through the SCS, the GNSS-R data improve the realism of the three largest eddies. The temperature sections along the typhoon track show large differences in the upper 200 m depths in excess of 1 °C near the shelf break. Finally, diagnostics of Degree of Freedom for Signal (DFS) provide a quantitative Impact Factor (IF) of the GNSS-R altimetry data over the conventional altimeter data. On average in July, the IF is low (

中文翻译：

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对 GEROS-ISS 任务的 GNSS-R 测高数据的 OSSE 评估，作为对现有观测网络的补充

摘要 来自全球导航卫星系统 (GNSS) 的模拟信号在海面反射并在低地球轨道卫星上接收，已被用于推导海面高度 (SSH) 并在观测系统模拟实验 (OSSE) 中同化为海洋模型。 ）。该实验方法被命名为 GNSS 反射计 (GNSS-R)，它是为国际空间站 (ISS) 提出的。这项科学实验是在 ESA 任务的框架内进行的，该任务称为“国际空间站上的 GNSS 反射测量、无线电掩星和散射测量”（GEROS-ISS）。在这项研究中，GNSS-R 模拟器考虑了计划中的 GNSS-R 高度计的三个不确定性来源：对流层、电离层和噪声项。针对南海（SCS）涡旋分辨混合坐标海洋模型（HYCOM）建立了集合最优插值（EnOI）数据同化系统，并于2014年6月18日至7月31日进行了两次数据同化运行带和不带 GNSS-R。在同化 GNSS-R 的运行中，除了来自当今高度计的传统海平面异常 (SLA) 之外，还进行了测量。尽管单个 GNSS-R 检索的精度较低，但与仅传统高度计数据相比，7 月份获得的结果显示均方根差 (RMSD) 总体提高了 14%。考虑到台风 Rammasun 穿过 SCS，GNSS-R 数据提高了三个最大涡流的真实感。台风路径沿线的温度剖面在上层 200 m 深度上有很大差异，在货架断裂附近超过 1 °C。最后，信号自由度 (DFS) 的诊断提供了 GNSS-R 测高数据相对于传统高度计数据的定量影响因子 (IF)。平均而言，7 月份的 IF 较低（