Atmospheric Temperature Models for Short-Range EDM

Abstract

For short-range electronic distance measurements (EDM) of the highest accuracy, an additional correction is needed to account for the difference between meteorological values at the end points and along the path of the measurement. Models are developed making use of formulations for the temperature gradient derived from atmospheric physics. The corrections depend on the surface profile below the line. For unstable atmospheric stratification the main meteorological parameter is the upward heat flux H. For a stable atmosphere, additional parameters are surface roughness and wind speed. Calculation of a typical example shows that under unstable atmospheric conditions the additional correction can be over 2 ppm, and for a stable atmosphere it may reach 4 ppm.