Multiple Scattering in Cirrus Clouds and Taking It into Account When Interpreting Lidar Measurements in the Stratosphere
V. A. Korshunov
Abstract
Multiple scattering arising in cirrus clouds in the process of lidar sensing of the atmosphere is studied using the Monte Carlo method. The calculations are performed for model scattering phase functions corresponding to crystalline cirrus cloud particles with sizes from 20 to 100 µm. A critical analysis of some common methods for multiple scattering correction in cirrus clouds is carried out. Numerical experiments on sensing cirrus clouds and stratospheric aerosol from the Earth’s surface with signal calibration at an altitude of 30 km are conducted. It is shown that ignoring the multiple scattering in this measurement scheme leads to a considerable distortion of the altitude profile of the backscattering coefficient in cirrus clouds and above them; at the same time, errors in the determination of the optical thickness of the clouds remain insignificant. An iteration scheme for taking into account multiple scattering is proposed and tested in numerical experiments. The simulation results are compared with experimental data.