Department of Geography

Atmospheric aerosols

Saharan dust plumeFig. 1: A Saharan dust plume transported over the Atlantic. Dust affects the planet’s energy balance and can fertilise the ocean and land.

The Earth's atmosphere contains countless tiny particles (aerosols), which come from many sources, including land surfaces, volcanoes, the oceans, plants and industrial activities. These play an important role in the climate system by directly modifying the radiation budget, and indirectly through influencing cloud properties, the atmospheric circulation, and global bio-geochemical cycles. Mineral dust aerosols are the dominant aerosol type globally. These are mostly emitted from the world's deserts and are transported in great plumes many thousands of km from their sources (Fig 1).

However, our understanding of how these aerosols are emitted and transported and how they affect climate remains relatively poor and so dust remains a major source of uncertainty in climate simulations.  Work at Sussex seeks to understand the dust cycle and the associated direct and indirect climate impact.
The aim is to improve the representation of dust aerosol processes in global and regional climate models. Our emphasis is on the Sahara desert, the world's greatest source region of dust.

Fennec - flying lowFlying low over the Sahara desert in the UK research aircraft during the Fennec field campaign. The aircraft bristles with instruemtns to measure the atmisphere, aerosols, and clouds.

Key staff: Martin Todd

Example projects

  • Fennec: The Saharan climate system

This international project involving researchers from UK, North Africa, Europe, and the USA provided the most comprehensive observations ever made of dust aerosols and the state of the atmosphere in the centre of the Sahara during the extreme summer dust season.

Watch the movie on YouTube  and  find out more on Wikipedia

 

  • The Bodele depression: the world’s dustiest place

The Bodele depression, an ancient lake bed in Northern Chad, is the world greatest source of dust. Sussex researchers have found what are the unique conditions that explain the phenomenon and have helped put this unsung natural wonder on the map.

Find out more

Bodélé Depression in ChadBodélé Depression in Chad.Bodélé Depression in Chad. The Tibesti and Ennedi mountains accelerate the northeasterly Harmattan winds. This "windtunnel" focuses the a Low Level Jet onto the ancient lake sedimentsn in the depression creating large oplumes of white dust. These events happen on average about 100 days per year.

Selcted publications

Bodele - Sussex researchersSussex researchers hard at work on the Bodele Depresssion during a dust storm

Marsham, J H, Hobby, M, Allen, C J T, Banks, J R, Bart , M, Brooks, B J, Cavazos-Guerra, C, Engelstaedter, S,Gascoyne, M, Lima, A R, Martins, J V, McQuaid, J B, O'Leary, A, Ouchene, B, Ouladichir, A, Parker, D J, Saci, A,Salah-Ferroudj, M, Todd, M C and Washington, R (2013) Meteorology and dust over the central Sahara: observations from Fennec supersite-1 during the June 2011 intensive observation period. Journal of Geophysical Research, 118 (10). pp. 4069-4089. ISSN 2169-8961

Knippertz, Peter and Todd, Martin (2012) Mineral dust aerosols over the Sahara: Processes of emission and transport, and implications for modelling. Reviews of Geophysics, 50 (1). ISSN 8755-1209

Knippertz, Peter and Todd, Martin C (2010) The central west Saharan dust hot spot and its relation to African easterly waves and extratropical disturbances. Journal of Geophysical Research: Atmospheres, 115 (D12,27). pp. 1-14. ISSN 0148-0227

Todd, M.C., Martins, V., Washington, R., Lizcano, G, Dubovik, O., M'Bainayel, S., and Engelstaedter, S., 2007. Mineral dust emission from the Bodele Depression, Chad during BoDEx. 2005. Journal of Geophysical Research 112, D06207, doi:10.1029/2006JD007170

Koren, I., Kaufman, Y.J., Washington, R., Todd, M.C., Rudich, Y., Martins, V. J. and Rosenfeld, D., 2006. The Bodélé depression-a single spot in the Sahara that provides most of the mineral dust to the Amazon forest. Env. Res. Lett., 1, 1-5

X. Xie, X. Liu, Y. Peng, Y. Wang, Z. Yue, and X. Li (2013) Numerical simulation of clouds and precipitation depending on different relationships between aerosol and cloud droplet spectral dispersion, Tellus B, 65, 19054.


Bodélé Depression in Chad image: Wikipedia