CONTRIBUTION TO THE ATMOSPHERIC MINERAL AEROSOL LOAD FROM LAND-SURFACE MODIFICATION

An estimation of the contribution of mineral dust from disturbed soils (i.e., soils affected by human activity and/or climate variability) t o the total atmospheric mineral aerosol load is presented. A three-dim ensional atmospheric dust transport model was used to simulate the dis tribution of dust optical thickness in response to individual dust sou rces, which include natural soils known to have been affected by the S aharan/Sahelian boundary shift, cultivation, deforestation, and wind e rosion. The distributions extracted from advanced very high resolution radiometer (AVHRR) optical thickness retrievals were used to constrai n likely source combinations. The results indicate that observed featu res Like the seasonal shift of maximum optical thickness caused by Sah aran dust over the Atlantic ocean are best reproduced if disturbed sou rces contribute 30-50% of the total atmospheric dust loading.