Is the depolarization ratio a global characteristic of mineral dust particles? Review on existing multiwavelength lidar measurements

Abstract

Multi-wavelength lidar measurements of the particle linear depolarization ratio of mineral dust layers at various locations around the Earth are presented from a comprehensive literature review. The values at a wavelength of 532 nm as well as the spectral slope of the depolarization ratio exhibits no significant difference between the Sahara, Arabia and Central Asia. The main difference was observed between freshly emitted and transported dust. Fresh dust has a higher depolarization ratio probably due to a higher amount of large dust particles. The depolarization ratio tends to decrease during transport time. This effect is strongest at 1064 nm and almost not present at 355 nm.