A Real-Time Precipitable Water Vapor Monitoring System Using the National GNSS Network of China: Method and Preliminary Results
A Real-Time Precipitable Water Vapor Monitoring System Using the National GNSS Network of China: Method and Preliminary Results
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DOI：
10.1109/jstars.2019.2906950
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发表时间：
2019-04
影响因子：
5.5
通讯作者：
Hongxing Zhang;Yunbin Yuan;Wei Li;Baocheng Zhang
中科院分区：
文献类型：
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作者：
Hongxing Zhang;Yunbin Yuan;Wei Li;Baocheng Zhang
国际全球导航卫星系统(全球导航卫星系统)服务实时试点项目的发展显示了利用全球导航卫星系统实时反演可降水量的前景。为了更好地应用于中国地区的GNSS实时气象，提出了利用中国国家GNSS网络建立GNSS-PWV实时监测系统的方法。产生天顶对流层延迟(ZTD)的原型系统基于实时精密单点定位技术，处理实时数据流和状态空间代表卫星的轨道和时钟改正。该系统将并行计算技术嵌入到实时数据流的解码和处理中，实现了多站处理模式，提高了计算效率。在初始阶段，利用中国地壳运动观测网络中的215个全球定位系统站来生成实时GPS-ZTD。从配置的气象传感器获得了分离天顶湿延迟(ZWD)和ZTD的压力数据。该系统采用了一种先进的加权平均温度模式，即网格混合TM模式，以实时的方式确定Π(将GPS-ZWD转换为GPS-PWV)。所生成的实时GPS-PWV产品具有5min的时间分辨率。为了验证系统的性能，对实时GPS-PWV与由附近探空数据(RS-PWV)得到的PWV以及美国国家环境预测中心(NCEP)-能源再分析II(NCEP-II-PWV)的再分析数据进行了83天的比较。比较表明，实时−-PWV与RS-PWV之间的平均偏差为0.1%mm，均方根值为1.7%mm。实时GPS-PWV和NCEP-II-PWV之间的一致性在均方根方面约为2.0亿毫米，平均偏差为−0.8百万毫米。这些结果证实了所建立的系统可以用于中国全程的PWV实时监测。
The development of the International Global Navigation Satellite System (GNSS) Service (IGS) Real-Time Pilot Project shows promise for real-time GNSS-based precipitable water vapor (GNSS-PWV) retrieval. For better applications of real-time GNSS meteorology over China, a method is proposed to establish a real-time GNSS-PWV monitoring system using the national GNSS network of China. The prototype system generating the zenith tropospheric delay (ZTD) is based on the real-time precise point positioning technique, in which the real-time data streams and state-space-representative satellite orbit and clock corrections are processed. The parallel computing technology is embedded in the system for decoding and processing the real-time data streams, which enables the multistation processing mode and improves the computing efficiency. At the initial phase, a total of 215 global positioning system (GPS) stations from the crustal movement observation network of China are used to generate the real-time GPS-ZTDs. The pressure data for separating the zenith wet delay (ZWD) from the ZTD are obtained from the collocated meteorological sensors. An advanced weighted mean temperature model, namely, Gridded-Mixed Tm, is adopted in the system to determine the conversion factor “Π” (converting GPS-ZWD to GPS-PWV) in real-time mode with the measured temperatures input. The generated real-time GPS-PWV products have a time resolution of 5 min. To validate the system performance, comparisons between the real-time GPS-PWV and the PWVs derived from nearby radiosonde data (RS-PWV) and reanalysis data from the National Centers for Environmental Prediction (NCEP)-Department of Energy Reanalysis II (NCEP-II-PWV) are conducted over a period of 83 days. The comparisons show a mean bias of −0.1 mm with a root mean square (RMS) of 1.7 mm between the real-time GPS-PWV and RS-PWV. The agreement between the real-time GPS-PWV and NCEP-II-PWV is approximately 2.0 mm in terms of RMS and has a mean bias of −0.8 mm. These results confirm that the established system can be used for real-time PWV monitoring across China.