Constructing an Observational Model of the Neutral Atmospheric Refraction Delay from Measured Values of the Astronomical Refraction
Constructing an Observational Model of the Neutral Atmospheric Refraction Delay from Measured Values of the Astronomical Refraction
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DOI：
10.1086/522943
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发表时间：
2007-10
期刊：
影响因子：
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通讯作者：
W. Mao;Binhua Li;Lei Yang;Q. Tie;Han-wei Zhang
中科院分区：
文献类型：
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作者：
W. Mao;Binhua Li;Lei Yang;Q. Tie;Han-wei Zhang
本文讨论了全球定位系统对中性大气折射延迟精确改正的要求，指出现有的理论改正模型和旧的后处理方法不能达到预期的精度，因为大气折射指数还没有直接精确测定。为了提高改正精度，有必要采用大气折射延迟模型。该模型依赖于观测站和观测方位。利用本文提出的新方法，将不同方位角和不同天顶距的天文折射观测资料按方位角分组，计算出折射率活度和映射函数。作为新方法的一个实例，本文介绍了低纬子午环的结构和瞬时天文折射的测量方法，并给出了云南天文台东、南、西、北四个方向的观测天文折射模型。我们估计，在不使用任何大气分布模型的情况下，天顶延迟的改正精度将在1 mm以内，低仰角折射延迟的改正精度将提高到厘米量级，截止仰角将减小到5°或更小。
Discussing the requirements for an accurate correction of the neutral atmospheric refraction delay for the Global Positioning System, our paper points out that the existing theoretical correction models and the old postprocessing methods cannot attain the anticipated accuracy because the atmospheric refraction index has not been directly determined precisely. It is necessary to adopt atmospheric refraction delay models to improve the correction accuracy. The models are dependent on the observing station and the observation azimuth. By the new method we propose in this paper, the observational data of astronomical refractions at different azimuths and different zenith distances are grouped according to azimuth and used to calculate the refractivity and mapping functions. As an example of the new method, we introduce the configuration of the Lower Latitude Meridian Circle and the measurement method of instantaneous astronomical refractions, and present the observational astronomical refraction model toward the east, south, west, and north of the Yunnan Observatory. We estimate that, without the use of any atmospheric distribution models, the correction accuracy of the zenith delay will be within 1 mm, the correction accuracy of the refraction delay at the lower elevation will be improved to a centimeter magnitude, and the cutoff elevation angle will be reduced to 5° or less.