ATMOCHEM - Interaction of trace gases with mineral dust: Impact on atmospheric photochemical cycles and dust properties

• Applicants: Dr. John Crowley; Dr. Bernhard Vogel
• Subject Area: Atmospheric Science
• Term: from 2008 to 2013
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 82737145

This project includes experimental (laboratory based) and theoretical (atmospheric modelling) studies of the impact of mineral dust on several aspects of atmospheric / environmental science. The laboratory studies are designed to investigate the interactions of several important atmospheric trace-gases with authentic (Saharan, Chinese, Arizona) and synthetic, airborne mineral aerosol samples under conditions which are relevant for the atmosphere. The use of dispersed, airborne dust samples (rather than bulk substrates) will enable the physical-chemical parameters that describe the process to be transferred with a high level of confidence to the real atmosphere. The parameters obtained include uptake coefficients / capacities and reaction mechanisms and their dependence on atmospheric variables such as relative humidity, intensity of irradiation by sunlight and concentrations of other trace gases. The trace gases under investigation include atmospheric species that are likely to have significant impacts on the atmospheric NOy, NOx and HOx budgets and O3 mixing ratios. Furthermore, the experimental data will enable assessment of the impact of such trace-gas interactions on the optical and cloud forming properties of mineral dust. The global and regional impact of the processes studied in the laboratory will be assessed in atmospheric models which have realistic dust emission schemes, and tested representations of trace-gas aerosol interactions including the effect of the atmospheric variables mentioned above. The role of mineral dust in changing concentrations of e.g. key NOx reservoirs, the HO2 / OH budgets and both direct and indirect impacts on tropospheric ozone will be assessed within a realistic framework of known gas-phase reactions and other aerosol types (sulphate and sea-salt). In addition, the effects of chemical ageing / changing hygroscopic properties of mineral dust during transport and the associated impact on optical properties and modification of clouds / precipitation and the radiation budget will be assessed. Once improved with the new laboratory data, the models will be in a position to provide more accurate prognoses of the effects of e.g. future pollutant emissions under different dust loading scenarios.

• DFG Programme: Research Grants
• International Connection: France
• Participating Persons: Dr. Barbara D' Anna; Dr. Yves Balkanski