The Size Distribution of Desert Dust and Its Impact on the Earth System

Thursday, 18 December 2014
Natalie M Mahowald1, Samuel Albani2, Jasper F Kok3, Sebastian Engelstaedter4, Rachel Scanza2, Daniel S Ward2 and Mark Flanner5, (1)Cornell University, Department of Earth and Atmospheric Sciences, Ithaca, NY, United States, (2)Cornell University, Ithaca, NY, United States, (3)University of California Los Angeles, Atmospheric and Oceanic Sciences, Los Angeles, CA, United States, (4)Oxford University, Oxford, United Kingdom, (5)University of Michigan, Ann Arbor, MI, United States
The global cycle of desert dust aerosols responds strongly to climate and human perturbations, and, in turn, impacts climate and biogeochemistry. Here we focus on desert dust size distributions, how these are characterized, emitted from the surface, evolve in the atmosphere, and impact climate and biogeochemistry. Observations, theory and global model results are synthesized to highlight the evolution and impact of dust sizes. Individual particles sizes are, to a large extent, set by the soil properties and the mobilization process. The lifetime of different particle sizes controls the evolution of the size distribution as the particles move downwind, as larger particles fall out more quickly. The dust size distribution strongly controls the radiative impact of the aerosols, as well as their interactions with clouds. The size of particles controls how far downwind they travel, and thus their ability to impact biogeochemistry downwind of the source region.