Measurement Methods and Applications of Atmospheric Refractivity Based on Raman Lidar

Abstract. Atmospheric refractive index stratification significantly affects the propagation of electromagnetic waves. High-vertical-resolution atmospheric refractivity (N) data acquired within the near-surface layer can be used to effectively evaluate the operational effectiveness of electronic equipment. On the basis of the principle of Raman scattering, an N measuring instrument utilizing Raman lidar was designed. It achieves high-vertical-resolution detection of temperature and humidity profiles within the 2.4 to 120 m altitude range and calculates the N on the basis of these data via the hypsometric formula. A field comparison test was conducted in 10 to 26 January 2024 LT using layered observation data from a gradient tower. The overall root mean square error (RMSE) of the Raman lidar for air temperature (AT) and relative humidity (RH) detection were 0.50 °C and 3.11 %, respectively; the overall RMSE for N detection was 2.65 N-units. With respect to the altitude layer, the AT, RH, and N detection mean absolute error (MAE) ranged from 0.34 to 0.54 °C, 1.90 to 3.53 %, and 1.87 to 2.35 N-units, respectively. This research provides an effective method for measuring the N.