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Shape-Induced Gravitational Sorting Of Saharan Dust During Transatlantic Voyage: Evidence From Caliop Lidar Depolarization Measurements, Weidong Yang, Alexander Marshak, Alexander Kostinski, Tamás Várnai

Department of Physics Publications

Motivated by the physical picture of shape‐dependent air resistance and, consequently, shape‐induced differential sedimentation of dust particles, we searched for and found evidence of dust particle asphericity affecting the evolution and distribution of dust‐scattered light depolarization ratio (δ). Specifically, we examined a large data set of Cloud‐Aerosol Lidar with Orthogonal Polarization (CALIOP) observations of Saharan dust from June to August 2007. Observing along a typical transatlantic dust track, we find that (1) median δ is uniformly distributed between 2 and 5 km altitudes as the elevated dust leaves the west coast of Africa, thereby indicating uniformly random mixing of particle …