1. Atmospheric Controls on North African Dust Emission Richard Washington Sebastian Engelstaedter Martin Todd, Gil Lizcano Fiona Mitchell Yoram Kaufman, Ilan Koren Oxford, UCL, GSFC NASA,

2. JANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDEC Annual dust cycle of TOMS AI (1980-92)

3. Washington and Todd 2005 GRL Mean JFM Zonal Wind: latitude-height along 18 E

4. Washington and Todd 2005 GRL Bodele daily dust Vs 1000 hPa geopotentials and 950 vector winds (JFM)

5. Tibesti Ennedi Gap Flow Bodele LLJ Palaeo Lake

6. Phase of TOMS AI 1980-1992

7. Dust in Colour Rainfall black contours

8. Annual Cycle of TOMS AI Vs Annual Cycle of ERA-40 Surface Wind

9. Annual Cycle of TOMS AI Vs Annual Cycle of ERA-40 Surface Divergence

10. Mean TOMS AI for main dust season May-Aug (1980-92) WA1 WA2 WA3 WA4 BOD EA

11. WA1WA2WA3WA4BODEA Mean TOMS AI for dust season May-Aug (1980-92) Engelstaedter and Washington in prep

14. Annual Cycle of TOMS AI Vs Annual Cycle of ERA-40 surface gustiness

15. Eastern Sahara (Chad): Mean wind controls aerosol production Western Sahara (Mali/Mauri heat low): surface convergence and wind gustiness fits annual cycle better

16. Parcel trajectory density climatology July (1979-98) Djouf region (17.5-22.5N, 2.5-7.5W) % trajectories remain over Sahara (> 15N < 30N) 69 33 6 % trajectories crossing the 15W meridian 33 66 83 After days 3 5 10