Description: Tropospheric refraction account algorithms are analyzed for calculating the altitude of air objects according to radar measurements in existing airspace monitoring radars. The magnitude of the refraction correction depends on the radius of beam curvature, which depends on the gradient of the light refractive index in the atmosphere. The main problem is that the law of light refractive index gradient change is random, since it depends on the state of the atmosphere at different altitudes. In existing airspace radars, target heights are calculated without taking into account the current state of the troposphere. Separate attempts to take into account the current state of the atmosphere at the point where the radar station was located were not successful in calculating the refraction correction. The reasons for this will be investigated in the article based on the analysis of experimental data on the vertical sounding of the atmosphere in the Kharkiv region for the last 30 years. The article compares the values of corrections for refraction using different atmospheric models and corrections were calculated using experimentally obtained vertical profiles of the refractive gradient of light in the atmosphere. It is proved that in the absence of data on the current state of the atmosphere throughout the wave propagation path, which actually corresponds to the practice, it is better to use the aver-age high-altitude profile of the light refractive index gradient obtained by averaging the experimental data of the vertical sound-ing of the atmosphere in the radar location for the last 10 ... 15 years .
Keywords: height accuracy, three-dimensional radar, radar altimeter, atmospheric radio waves refraction, coefficient of re-fraction.