Airborne temperature profiling in the troposphere during daytime by lidar utilizing Rayleigh-Brillouin scattering.

Abstract

The airborne measurement of a temperature profile from 10.5 km down towards ground (≈1.4km above sea level) during daytime by means of a lidar utilizing Rayleigh-Brillouin (RB) scattering is demonstrated for the first time, to our knowledge. The spectra of the scattered light were measured by tuning the laser (λ=354.9nm) over a 11 GHz frequency range with a step size of 250 MHz while using a Fabry-Perot interferometer as a spectral filter. The measurement took 14 min and was conducted over a remote area in Iceland with the ALADIN Airborne Demonstrator on-board the DLR Falcon aircraft. The temperature profile was derived by applying an analytical RB line shape model to the backscatter spectra, which were measured at different altitudes with a vertical resolution of 630 m. A comparison with temperature profiles from radiosonde observations and model temperatures shows reasonable agreement with biases of less than ±2K. Based on Poisson statistics, the random error of the derived temperatures is estimated to vary between 0.1 K and 0.4 K. The work provides insight into the possible realization of airborne lidar temperature profilers based on RB scattering.