The propagation path of satellite signals in the atmosphere is a curve thus it is very difficult to calculate its flexure correction accurately, a strict calculating expressions has so far not been derived. In this study, the flexure correction of the refraction curve is divided into two parts and their strict calculating expressions are derived. By use of the standard atmospheric model, the accurate flexure correction of the refraction curve is calculated for different zenith distance Z . On this basis, a calculation model is structured. This model is very simple in structure, convenient in use and high in accuracy. When Z is smaller than 85°,the accuracy of the correction exceeds 0.06 mm. The flexure correction is basically proportional to tan 2 Z and increases rapidly with the increase of Z . When Z >50°,the correction is smaller than 0.5 mm and can be neglected. When Z >50°, the correction must be made. When Z is 85° , 88° and 89° , the corrections are 198 mm, 8.911 m and 28.497 km, respectively. The calculation results shows that the correction estimate by Hopfield is correct when Z ≤80 °, but too small when Z =89°. The expression in this paper is applicable to any satellite.
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