A near real-time troposphere tomography system (WATS-NRT) based on Global Positioning System (GPS) slant wet delays (SWD) was developed to reconstruct three-dimensional wet refractivity fields over a wide area. The NCEP Global Forecast System (GFS) short-range forecast products (GFS-FC) were taken as the tomography background to tackle the ill-condition issue, and the Adaptive Simultaneous Iterative Reconstruction Technique (ASIRT) was used for parameter estimation to avoid an inversion of a large sparse matrix. Experiments were set up for a 7-day period covering a severe storm event to evaluate the performance of the tomography system over an area with about 5000 tomographic nodes. Statistics of the computation time illustrate that WATS-NRT is efficient enough for providing 30 min interval tomography products in the studied area. Wet refractivity time series from the tomography product experience dramatic rises before the advent of heavy rain, which is not presented in the GFS-FC products. Comparisons also show general better agreements with the nearby radiosonde profiles in tomography products than GFS-FC, especially at the lower troposphere. In addition, average error RMS of SWD derived from tomography products is about 38 mm at an elevation of 15° and 9 mm in the zenith direction, compared to more than 70 and 16 mm for SWD from both GFS-FC and the reanalysis product ERA5, and compared to about 44 and 9 mm for ZWDINT method. These results suggest that WATS-NRT can be promising in some applications, such as monitoring extreme weather events, providing tropospheric delay estimates in geodetic data analysis and developing new mapping functions.

中文翻译：

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使用自适应同步迭代重建技术的快速对流层断层扫描

开发了一种基于全球定位系统 (GPS) 倾斜湿延迟 (SWD) 的近实时对流层断层扫描系统 (WATS-NRT)，以重建大范围内的三维湿折射场。以NCEP全球预报系统（GFS）短程预报产品（GFS-FC）作为断层扫描背景解决病态问题，并采用自适应同步迭代重建技术（ASIRT）进行参数估计以避免大稀疏矩阵的求逆。实验进行了为期 7 天的涵盖严重风暴事件的实验，以评估断层扫描系统在具有约 5000 个断层扫描节点的区域内的性能。计算时间的统计表明，WATS-NRT 足以在研究区域提供 30 分钟间隔的断层扫描产品。来自断层扫描产品体验的湿折射率时间序列在大雨来临之前急剧上升，这在 GFS-FC 产品中没有出现。比较还表明，与 GFS-FC 相比，断层扫描产品中与附近无线电探空仪剖面的总体一致性更好，尤其是在对流层低层。此外，来自断层扫描产品的 SWD 平均误差 RMS 在 15°仰角和天顶方向 9 mm 处约为 38 mm，相比之下，来自 GFS-FC 和再分析产品 ERA5 的 SWD 均超过 70 和 16 mm ，并与 ZWDINT 方法的约 44 和 9 毫米相比。这些结果表明 WATS-NRT 在某些应用中很有前景，例如监测极端天气事件、在大地测量数据分析中提供对流层延迟估计以及开发新的绘图功能。