Dr. Liz Pillar-Little-May 3 BUL Seminar

Name:     Dr. Liz Pillar-Little

Title:    Toward understanding the formation and aging of aerosol: an experimental and observational approach

Location: NWC 5600

Date:     2019/05/03

Time:     02:00 PM

Series:   Boundary Layer, Urban Meteorology, and Land-Surface Processes

Abstract: Atmospheric aerosols play an important role in climate by scattering and absorbing radiation and by serving as cloud condensation nuclei. An aerosol’s optical or nucleation properties are driven by its chemical composition. Chemical aging of aerosols by atmospheric oxidants, such as ozone, alters the physiochemical properties of aerosol to become more hygroscopic, light absorbing, and viscous during transport. However, the mechanism of these transformations is poorly understood. While ozone is a protective and beneficial atmospheric gas in the stratosphere, it is a potent greenhouse gas in the troposphere that traps heat near the Earth’s surface. It also impacts human heath by irritating the respiratory tract and exacerbating cardiovascular diseases. Additionally, ozone can alter the ecosystem through oxidizing plant foliage which can lead to deforestation and crop losses as well. Both gases and aerosols in the troposphere can react with ozone directly and indirectly wi

th hydroxyl radicals. While daytime aging is thought to be primarily driven by photochemical processes and hydroxyl radicals, ozone is thought to be a key player in nighttime or dark aging processes that can alter the physicochemical properties of aerosols. Measured concentrations of trace gases and aged aerosol components in the field are higher than values predicted based on laboratory studies and computer simulations. Consequently, new experimental approaches are needed to narrow the gaps between observations and mechanistic understandings.

This presentation will discuss laboratory experiments that utilized aerosol mimics to understand how phase (solid or liquid) and water content of aerosols can influence the products of heterogeneous processing at the air-aerosol interface.  These results suggested that a better understanding of how meteorological variables and concentrations of trace gases can impact aerosol size distributions and number density is needed. However, conventional measurement strategies do not provide a lot of information regarding the spatio-temporal distribution of these variables in the troposphere. Unmanned aerial systems (UAS) provide an adaptive and economic platform to measure atmospheric variables in the troposphere where most aerosol formation occurs. An overview of preliminary results from field experiments using UAS will be presented as well as an outline of envisioned future studies aimed at characterizing the interplay between weather, aerosols, and gas inventories.