ROLES OF TROPOSPHERIC OZONE AND AEROSOLS IN CLIMATE CHANGE
Mengfang Li
Pennsylvania State University, State College, Pennsylvania
1. INTRODUCTION
Human activities, such as burning fossil fuels, release into the atmosphere two short-lived pollutants that affect global climate – ozone and aerosol particles. Although ozone plays a crucial role in protecting Earth’s surface from ultraviolet radiation, it is a greenhouse gas produced by industrial processes that stays in the troposphere. Like all greenhouse gases, ozone influences the atmospheric temperature, humidity and winds. Aerosol particles, defined as suspended small particles with widely varying size, affect climate by either absorbing or reflecting sunlight. The increase in atmospheric concentrations of man-made ozone and aerosols from sources such as transportation, agriculture, industry, and use of urban land pose serious problems to human health, but also have a significant effect on weather and climate.
2. MODERN TROPOSHPERE OZONE AND AEROSOL FORMATION AND DISTRIBUTIONS
Troposphere ozone and aerosols are radiatively important species, whose concentrations have dramatically increased since industrialization and tend to continue changes in the future. (Staehelin et al., 2001) Based on the Intergovernmental Panel on Climate Change Special Report on Emissions Scenarios in 2007, its measurement shows that the troposphere ozone has increased by 50% and anthropogenic aerosols have increased by factor of 6. (Ramaswamy et al., 2001)
Ozone is a molecule that consists of three oxygen atoms bound together. It is highly reactive and unstable. Like other greenhouse gases, ozone is a radiative active compound. It contributes to global warming by absorbing long-wavelength infrared from the Earth’s surface.
In the lower atmosphere (troposphere), ozone is usually formed by a complex reaction between two different chemicals: nitrogen oxide (NOx) and volatile organic compounds (VOCs)....