大气折射母函数方法、大气折射解析解和映射函数

回顾了作为实用天文学和大地测量学中基本研究课题之一的大气折射映射函数研究的进展。介绍了近几年上海天文台发展的大气折射母函数方法 ,以及由此导出的大气折射解析解。对如今广泛地应用在空间测量技术中的几种映射函数做出评述 ;分析了NMF模型的优点和不足之处。介绍了由大气折射母函数方法引出的大气延迟新连分式映射函数和天文大气折射的映射函数方法。利用VLBI实验中高度截止角与基线长度重复率的关系、探空气球 (radiosonde)观测资料、PRARE资料比较了各种映射函数的结果。特别指出了映射函数方法对天文大气折射和光学波段测距精度的改进。讨论了大气折射计算中的主要误差源。

THE GENERATOR FUNCTION METHOD, ANALYTIC SOLUTION AND MAPPING FUNCTION IN ATMOSPHERIC REFRACTION

The development of the mapping function of atmospheric refraction, which is a basic research project in practical Astronomy and Geodesy, is listed in this paper. The generator function method of atmospheric refraction recently developed in Shanghai Astronomical Observatory (SHAO), and the introduced analytic solution of atmospheric refraction are reviewed. Some mapping function expressions widely used in space techniques today are analyzed. The advantages and disadvantages in Niell's mapping function (NMF) are examined. A new continued fraction form of the mapping function deduced from the generator function method is applied into both the atmospheric delay and the astronomical refraction. By the elevation cut-off tests in VLBI, radiosonde data sets and observation process in PRARE, the features of different mapping functions are discussed. The accuracy improvement on the astronomical refraction by applying mapping function is noticeable. The error sources in atmospheric refraction are studied.