摘要
大气折射映射函数研究中的母函数方法大大地提高了对流层大气折射改正的计算精度，进而提供了在近地平时低高度观测的足够高精度大气折射改正计算方法。作为高精度大气折射模型的进一步考虑，有限距离目标，例如小于几百千米高度，可能对大气延迟和天文大气折射都能引入额外的改正。本文应用了天文大气折射一些新定义，以及详细地讨论了一种有限距离目标的大气折射改正的计算模型，其中包含在映射函数中的角自变量从传统的真天顶距到本征天顶距的改变。对大气延迟和天文大气折射的模拟计算表明：本文结果对小平几百千米的目标在低于10°的观测具有一定的影响。
A new generator function method of computing mapping function and the introduced refractive delay models, UNSW931 and UNSW932, were discussed in (Yan and Ping l995,Yan et al. l996). The new theory offers a possibility to calibrate the computation accuracy of the tropospheric refraction correction in great deal. This improvement makes the elevation observations near' horizon be calculated with an efficient accurate refraction correction as well. As a further consideration of high accurate refraction model, a finite slant distance of object, for instance less than hundreds kilometers height, can introduce extra corrections in both refractive delay and astronomical refracti0n. In this paper, new definitions in astronomical refraction have been employed and a computation model of refraction for a finite distance object is considered in detail, that involves a change of angular argument in the mapping function from the conventionally used true zenith distance to the proper zenith distance- Simulate. numerical results are presented for refractive delay and astronomical re faction, that show a potential interest when observation elevation down to 1ower than 1O' for objects with height of hundreds kilometers.
出处
《中国科学院上海天文台年刊》
1997年第18期157-162,共6页
Annals Shanghai Astronomical Observatory Chinese Academy of Sciences
