Increase of error in range correction with elapsed time, evaluated by ray tracing through radiosonde‐generated atmospheric models

Previous studies of range and angular errors caused by variation of atmospheric refractivity with altitude generally have used functional expressions, averaged data, or data from a small number of radiosonde ascents. In this investigation a large data base was employed consisting of radiosonde measurements made at intervals of about 2 hr for a period of 1 week. In the analysis it was assumed that the refractivity varied only as a function of altitude and that there was no ducting. Curves showing the deterioration of range correction with time for selected terminal points were developed by tracing rays at a succession of elevation angles. Thus, for a ground range of 416.7 km and an aircraft at 15.24 km, the standard deviation of the ground‐to‐plane radio distance 4 hr after a radiosonde ascent is .9 m, increasing to 1.3 m after 8 hr, and 1.6 m after 12 hr.