Retrieval of Gas Temperature and Pressure in Brillouin Lidar Based on Reversal Modeling Method

In order to address the challenge of improving the retrieval accuracy of Rayleigh-Brillouin lidar using conventional retrieval method, a novel method called reversal modeling is proposed in this work. This method establishes a retrieval model using two sets of Rayleigh-Brillouin spectral (RBS) linewidths that have a reversal relationship. Theoretical analysis shows that the temperature fitted errors of novel method within 1K and 2K account for 95.3% and 100%, respectively, while the pressure fitted errors of novel method within 0.025bar and 0.05bar account for 98.1% and 100%, respectively. Furthermore, compared to dual-parameter model presented by Zhang in 2020, the novel model is of similar temperature theoretical errors but smaller pressure theoretical errors, as well as smaller temperature and pressure fitted errors under various wavelengths conditions, particularly achieving higher retrieval accuracy at shorter wavelengths. Finally, experimental results demonstrate that the mean relative temperature and pressure errors of the novel method are 0.22% and 4.093%, respectively, which are 50% lower than those of the conventional method.