Reliability of Refraction in Polar Astronavigation

The use of radiosonde data offers the possibility of overcoming restrictions imposed by the polar environment and of establishing the reliability of existing refraction tables for use in the Arctic and Antarctic. Analysis of limited radiosonde data from the Arctic indicates that with the exception of extremely large zenith angles there exists a high degree of correlation between the actual refraction and refraction values obtained from radiosonde data. Navigators and surveyors operating in the polar regions are often forced to rely on solar observations for their position determinations. The inherently large zenith angles and the resulting large refraction corrections associated with such observations have led many people to question the reliability of positions determined by such means. Reduction of radiosonde data from Thule Air Base, Greenland for a 7-week summer period shows a high degree of reliability for the refraction corrections.