A technical description of atmospheric sounding by GPS occultation
A technical description of atmospheric sounding by GPS occultation
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DOI：
10.1016/s1364-6826(01)00114-6
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发表时间：
2002-03-01
影响因子：
1.9
通讯作者：
Leroy, SS
中科院分区：
文献类型：
--
作者：
Hajj, GA;Kursinski, ER;Leroy, SS
近年来，通过无线电掩星技术利用全球定位系统获取中性大气中的电离层活动、温度、压力和水汽以及电离层中的电子密度的分布。全球定位系统MET实验将一个全球定位系统接收器置于近地轨道，提供了大量数据，用于检验这一概念和检索的准确性。一些调查已经表明，用GPS MET获得的检索精度即使不是更高，也已经相当。比更传统的大气感测技术（例如，无线电探空仪）。尽管通过无线电掩星观测大气剖面的概念相当简单。必须注意分离可能影响被掩蔽信号的众多因素。这些包括卫星的运动，时钟漂移。相对论效应、电离层和中性大气的分离以及倾斜大气的贡献，其中GPS信号的灵敏度较弱。此外，必须注意使用适当的边界条件。使用适当的平滑间隔和插值方案，以避免反演人为的大气结构，最重要的是检测和校正大气中急剧的放射性梯度所引入的相位测量误差。这项工作在一定程度上详细描述了处理这些数据所涉及的几个步骤。尤其是。它描述了一个由喷气推进实验室开发的用于处理GPS MET数据的系统。检索的活动，温度和水汽廓线的几个例子显示和比较，从欧洲中期天气预报中心（ECMWF）的分析。6月21日至7月4日期间收集的GPS MET和ECMWF温度数据的统计比较。1995.表明在ECMWF分析最精确北方纬度，差异为1-2 K。(C)2002爱思唯尔科技有限公司版权所有。
In recent years, the global positioning system (GPS) has been exploited via radio occultation techniques to obtain profiles of refractivity, temperature, pressure and water vapor in the neutral atmosphere and electron density in the ionosphere. The GPS MET experiment, which placed a GPS receiver in a low-Earth orbit, provided a wealth of data which was used to test this concept and the accuracy of the retrievals. Several investigations have already demonstrated that the retrieval accuracies obtained with GPS MET is already comparable, if not better. than the more traditional atmospheric sensing techniques (e.g.. radiosondes). Even though the concept of atmospheric profiling via radio occultation is quite a simple one. care Must be taken to separate the numerous factors that can affect the occulted signal. These include the motion of the satellites, clock drifts. relativistic effects, the separation of the ionosphere and the neutral atmosphere, and the contribution of the tipper atmosphere where sensitivity of the GPS signal is weak. In addition, care must be taken to use proper boundary conditions. use proper smoothing intervals and interpolation schemes to avoid retrieving artificial atmospheric structures, and most importantly detect and correct phase measurement errors introduced by sharp refractivity gradients in the atmosphere. This work describes in some detail the several steps involved in processing Such data. In particular. it describes a system that was developed at the Jet Propulsion Laboratory and used to process the GPS MET data. Several examples of retrieved refractivity, temperature and water vapor profiles are shown and compared to analyses from the European Center for Medium-range Weather Forecast (ECMWF). Statistical comparisons of GPS MET and ECMWF temperatures for data collected during June 21-July 4. 1995. indicate that differences are of order 1-2 K at northern latitudes where the ECMWF analyses are most accurate. (C) 2002 Elsevier Science Ltd. All rights reserved.