Improved method for gas temperature and pressure retrieval in Brillouin lidar remote sensing

The Rayleigh-Brillouin scattered spectrum is an important tool for analyzing the temperature and pressure of gas in Brillouin lidar remote sensing. The Tenti-S6 model has been widely used to retrieve atmospheric temperatures. However, the retrieval accuracy of this method is unsatisfactory. We analyzed the influence of several factors on the retrieval accuracy of this method and developed an improved method for temperature and pressure retrieval. First, the Rayleigh-Brillouin spectral baseline was corrected using a new fitting procedure, and an experimental spectrum that is of high coincidence with the line shape of the S6 model could subsequently be obtained. Second, the influence of the Airy function on the retrieval accuracy was analyzed, and the retrieval error could be decreased using the Tenti-S6 model without the Airy function. We found that the gas parameters could be precisely detected under low-pressure conditions. Compared with the traditional method, our improved method could effectively reduce the temperature and pressure retrieval errors. The experimental results of nitrogen scattering in the laboratory and air scattering demonstrate the effectiveness, universality, and viability of the proposed improved method.