Long-term measurements of the transport of African mineral dust to the southeastern United States: Implications for regional air quality

Continuous daily aerosol sampling carried out at a coastal site in Miami, Florida, for the past 23 years shows that large quantities of African mineral dust are periodically carried into Florida every summer, yielding daily concentrations in the range of about 10 mu g m(-3) to 100 mu g m-3. Dust events typically last several days or longer. The maximum dust concentration occurs in July (monthly mean, 16.3 mu g m(-3)), but relatively high concentrations are also observed in June (8.4 mu g m(-3)) and August (9.8 mu g m(-3)). There is considerable year-to-year variability that is apparently linked to various meteorological factors including climate conditions in North Africa as manifested by drought. Satellite data show that African dust incursions are synoptic-scale events; consequently, they will impact a large region of the southern and eastern United States. The incursion of dust events over this large region, coupled with inputs from local emissions, could have important implications regarding regional air quality.