The role of convective plumes and vortices on the global aerosol budget

Abstract

Atmospheric aerosols produce both a direct radiative forcing by scattering and absorbing solar and infrared radiation, and an indirect radiative forcing by altering cloud processes. Therefore, it is essential to understand the physical processes that contribute to the global aerosol budget. The International Panel on Climate Change (IPCC) reports that mineral dust contributes to ∼1/3 of all primary particle emissions to the atmosphere. The significance of mineral dust aerosol becomes evident when one considers the large surface area of arid and semi‐arid regions on most continents. It is evident from observations in the U.S. Southwest that convective plumes and vortices lift large quantities of desert dust. Here, we use a combination of observational data and theory to determine the role of convective plumes and vortices on the global aerosol budget. We show that convective plumes and vortices contribute to about 35% of the global budget of mineral dust.

Dynamical mechanisms controlling the vertical redistribution of dust and the thermodynamic structure of the West Saharan atmospheric boundary layer during summer

“…A diurnal cycle of dust load has been reported near the Sahelian and Saharan source regions (N'Tchayi Mbourou et al, 1997;Engelstaedter et al, 2006;Chaboureau et al, 2007), which is a result of daytime boundary-layer convection removing the nocturnal inversion, and affecting dust uplift and transport. Dust devils, which form in convective boundary layers with sheared but relatively light winds, may also be important in some regions (Koch and Renno, 2005). Dust uplift by density currents is also important in many locations (Sterk, 2002;Flamant et al, 2007 hereafter F07; Knippertz et al, 2007;Bou Karam et al, 2008;Marsham et al, 2008b).…”

Large Eddy Simulation on Dust Suspension in a Convective Mixed Layer

“…These convectively-induced horizontal winds can pick up small dust particles from the ground, although their amount may be much less than that by a severe dust storm. Several studies that combined observational data and theory suggest that convective plume and vortices play an important role in the global aerosol budget (Gillette and Sinclair 1990;Koch and Renno 2005). Since small dust particles may float in the convective mixed layer over several days, their concentrations could be amplified if fine weather continues.…”

History and Applications of Dust Devil Studies

“…On Earth, the first estimate by Koch and Renno (2005) was that dust devils may contribute by about 35 % to the total dust burden. More recent estimates suggest a contribution of about a factor of 10 less (∼3.4 %, Jemmett-Smith et al 2015).…”