REFRACTION EFFECTS ON VERTICAL ANGLE MEASUREMENTS

AbstractAtmospheric refraction is a major source of error in many survey observations, particularly vertical angle measurement. Much research work is being carried out into refraction effects on the more precise types of survey observation, such as electromagnetic distance measurement (e.g. Angus-Leppan and Brunner, 1980, and Dodson and Iliffe, 1982) and precise spirit levelling (e.g. Whalen, 1981, Holdahl, 1980, and Remmer, 1980) but less effort appears to have been directed in the area of vertical angle measurement (e.g. Brunner, 1978). This paper deals only with the effect of refraction on vertical angle observations. However, it is apparent that the meteorological variations which cause refraction problems are independent of the particular observation concerned and thus much of the theoretical reasoning given in this paper is of relevance to other types of measurement.