The Measurement of Tropospheric Temperature Profiles using Rayleigh-Brillouin Scattering: Results from Laboratory and Atmospheric Studies

Abstract

In this letter, we suggest a new method for measuring tropospheric temperature profiles using Rayleigh-Brillouin (RB) scattering. We report on laboratory RB scattering measurements in air, demonstrating that temperature can be retrieved from RB spectra with an absolute accuracy of better than 2 K. In addition, we show temperature profiles from 2 km to 15.3 km derived from RB spectra, measured with a high spectral resolution lidar during daytime. A comparison with radiosonde temperature measurements shows reasonable agreement. In cloud-free conditions, the temperature difference reaches up to 5 K within the boundary layer, and is smaller than 2.5 K above. The statistical error of the derived temperatures is between 0.15 K and 1.5 K.

Retrieval of Gas Temperature and Pressure Based on Rayleigh–Brillouin Spectrum

“…The pressure values adopted in the air experiment are close to 1.0 bar, with the temperatures ranging from 256 K to 340 K, which correspond to real atmospheric situations. The retrieval errors from the method presented in reference [15], [16] are all listed in Table 7 to interpret the optimal model we proposed for the simultaneous retrieval of gas temperature and pressure.…”

“…In other words, for the dual-parameter model, the upper limit of retrieval error in a characteristic model is based on Rayleigh linewidth, and the overall spectral linewidth is minimal when the error of the characteristics is 1 MHz. The accuracy of the retrieval result is acceptable for real remote-sensing applications [16]- [19].…”

“…For instance, in 2014, Witschas et al [15], [16] retrieved the temperature of a gas, at an accuracy of 2 K, from the RB spectrum using the Tenti-S6 model in laboratory conditions. In the same year, they showed that the temperature measurements are close to the radiosonde measurements at noon through the temperature profiles from 2 to 15.3 km in outdoor experiments.…”

Temperature Dependence of the Rayleigh Brillouin Spectrum Linewidth in Air and Nitrogen

“…As the echo signal intensity is disturbed by Mie scattering caused by aerosols in the troposphere, the Lidar technique is applied, based on frequency field detection methods such as rotational Raman Lidar [ 1 , 2 ] and Rayleigh Brillouin (RB) Lidar. These techniques function by resolving the spontaneous Rayleigh Brillouin (SRB) spectrum [ 3 , 4 ] to reduce the Mie scattering. The rotational Raman differential backscattering cross-section is smaller than that of Rayleigh scattering, which means that the rotational Raman Lidar need a more powerful laser, a more sensitive receiver system, and more integration time.…”

“…Also in 2014, the experimental data demonstrated that temperatures can be retrieved from SRB line shapes at an accuracy of 2 K based on Tenti S6 [ 18 ]. Furthermore, Witschas showed temperature profiles from 2 to 15.3 km derived from the SRB spectrum in 2015 [ 4 ]. The temperature measurements performed at noon showed good agreement to the radiosonde measurements.…”