Dust Deposition - Mineral Dust: A Key Player in the Earth System - page 176

Chapter 8
Dust Deposition

Gilles Bergametti and Gilles Forêt

Abstract During transport, dust particles experience deposition processes that
strongly affect their atmospheric lifetime and their radiative and geochemical
impacts. Dust particles are removed either by dry deposition mainly controlled
by gravity, impaction, and diffusion or by wet removal in or below clouds, all
processes being strongly size dependent. Theoretical models have been developed
to describe these processes, and parameterizations have been derived in order to
represent as precisely as possible the deposition of dust in 3D models. However,
direct measurements, especially for dry deposition, are difficult to perform and
consequently data are sparse, limiting our capability to test the accuracy of the
simulations of the dust deposition and thus to effectively constrain the dust mass
budget simulated by these models.

Keywords Dust deposition ￿ Particle size ￿ Wet deposition ￿ Dry deposition ￿
Dust models ￿ Advection ￿ Precipitation ￿ Scavenging ￿ Washout ￿ Rainout ￿
Collision

8.1 Introduction

The assessment of the impacts that desert dust has on the behavior of the Earth
system requires a reliable estimation of the dust concentration in the atmosphere
and of its variability in space and time. It also requires information on the dust size
distribution (see Chap. 2 ) and on the dust composition, since these characteristics
control both radiative (see Chap. 11 ) and biogeochemical (see Chap. 14 ) impacts
and deposition patterns. To do that, atmospheric dust models have to represent the