摘要
根据经典天体定位测量受天文大气折射的影响和现代空间大地测量对中性大气折射延迟改正的要求,分析了这些修正没有达到预期精度要求的原因:主要在于不能直接测定天文大气折射;文章针对这些影响量对大气分布模型的依赖性,改正值应随着不同的观测站和不同方位而异的要求,提出了提高这两种改正精度的有效途径:在各观测站不同方位的各天顶距,测定天文大气折射值,分别建立不同方位的大气折射实测模型,并利用实测数据,求解出折射率差和映射函数的参数,建立和采用随着观测站、随着方位而异的折射延迟改正模型。这一新方法的实施,将能在避免采用大气分布模型的情况下,把较低高度角的折射延迟改正精度从现在的米级提高到厘米级,并且把截止高度角压缩到5°以内。文章还论述了在各观测站多方向测定天文大气折射值的可能性。
According to influences of the astronomical angular refraction on classical astrometry and requirements of modern space geodesy to neutral atmospheric refractive delay corrections, the reasons why those corrections are not meet the demands of expected accuracy are analyzed, in which the main is that values of the angular refraction can not be determined directly by those methods. Aimed at the dependence of those influences on atmospheric distribution models and the requirement that the corrections should be varied with change in observing stations and observational directions, effective ways for improving accuracy of these two kinds of corrections are presented, that is, determining values of the astronomical refraction at different zenith distances in different directions at each station, building refraction models measured in different directions respectively, finding refractivity and parameters of mapping function using measured data, and constructing and adopting refractive delay corrective models varied with change in the stations and the directions. If the new technique is put in practice, in condition of not adopting atmospheric distribution model, the accuracy of the low-ahitu（le refractive delay correction will be improved from present meter level to centimeter level, and the cutoff elevation angle will be reduced to a range of 5°. The possibility of determining values of astronomical refraction in several directions at each station is discussed.
出处
《天文研究与技术》
CSCD
北大核心
2005年第4期232-239,共8页
Astronomical Research & Technology
关键词
大气折射
折射延迟
实测模型
astronomical refraction
refractive delay
measured model
