Drizzle microphysical property and vertical air motions retrieval using Doppler lidar and radar measurements.

The microphysical changes in cloud formation and development are closely related to the vertical air motions. It is difficult to simultaneously detect microphysical parameters of drizzle and vertical air motions. This study proposes a method for the drizzle microphysical property and vertical air motions retrieval using Doppler lidar and radar measurements. The wavelength of lidar is 1.55 µm, and it undergoes Mie scattering or geometric scattering in drizzle. The wavelength of radar is 8.6 mm, and it undergoes Rayleigh scattering or Mie scattering in drizzle. The difference in scattering mechanisms of two wavelengths enables them to retrieve the microphysical parameters of vertical air motions and raindrops. This wavelength-dependent backscattering cross section causes differently shaped reflectivity-weighted Doppler velocity spectra leading to wavelength-dependent mean Doppler velocity, and spectra width. In this algorithm, the echo power intensity, mean Doppler velocity and spectra width of lidar and radar are used for the retrieval of microphysical parameters and vertical air motions. The feasibility of the proposed method is simulated and analyzed, which is suitable for stratiform clouds rainfall with low turbulence. Finally, an observation case is provided and analyzed.