DU Aerosol Group
John Evans Professor Dr.Wilson leads the the University of Denver Aerosol Group. This research group develops and builds instruments and sampling inlets that we and other groups then use to study aerosols. Most of our measurements are made from aircraft platforms. Aerosols are collections of particles suspended in gas. The atmospheric aerosol comes from natural processes and human activities. The particles found in the air are very diverse in origin and chemical composition as the following examples show. Near the seashore, salt particles are abundant. Down wind of volcanic eruptions, we often find rocks, ash and sulfuric acid particles. High up in the atmosphere, meteors leave tiny debris particles in their wake as they burn up. We often live with the particulate results of combustion, construction and industry. In some places, the aerosol strongly resembles gasoline. Denver's brown cloud contains contributions from sources including the sand used on the streets, combustion products and particles formed from combustion products. SO2 emitted by power plants and other sources is oxidized to sulfuric acid that forms particles in the atmosphere. The concentration and size of atmospheric particles also vary dramatically. In the stratosphere, we often find fewer than 10 particles/cm3, but near a poorly designed or maintained diesel engine, the concentration can exceed a million particles/cm3. We measure particle diameters from 4 nm (1 nm= 10-9m) to 10 micrometer (1 micrometer = 10-6m).
Aerosol can affect many things we care about from human health to the manufacture of integrated circuits. The DU Aerosol Group has frequently studied the role of particles in stratospheric ozone depletion and in global climate change. We also study the sources and formation of pollution particles in urban and industrial settings, the emissions of aircraft and rockets and the processes that maintain the stratospheric aerosol. Many of these phenomena occur over a large scale, and we have made measurements at altitudes from sea level to over 70,000 ft (20 km). Our instruments have flown on NASA's ER-2, WB-57f and DC-8 research aircraft, NCAR's Gulfstream V. The German DLR has flown our instruments on their Falcon. The DU Low Turbulence Inlet is flown on the NOAA WP-3D, the NCAR C-130 and the UK Met Office and the Natural Environment Research Council FAAM aircraft (BAe-146). We have gone to Sweden, Chile, New Zealand, Australia, Alaska, Maine, California, the Virgin Islands, Japan, Costa Rica and points in between in pursuit of particles. Our instruments have gone to the North Pole and Antarctica without us.
Our instruments use light scattered from individual particles or controlled condensation of vapors on small particles followed by light scattering to tell us how many particles there are and how big they are. Our instruments and inlets are autonomous and computer controlled. They have passed the air-worthiness requirements of Lockheed-Martin, NASA, NOAA and NCAR, BAe Systems. Please browse our web site for additional information about our instruments, people, deployments, data analysis, aircraft platforms, or publications.