We are pleased to announce a School Seminar by Dr Zachary McQueen on the topic of: Radiative Properties of Atmospheric Components on Earth and Titan.
Abstract
The radiative budgets of both Earth and Titan’s (Saturn’s largest moon) atmospheres are greatly impacted by the composition of the trace gases and aerosol populations. A significant portion of Earth’s tropospheric aerosols consist of combustion aerosols derived from both natural (wildfires) and anthropogenic (engines, industrial processes, prescribed fires) sources. Constraining the direct radiative effects of Earth’s aerosols can be difficult in part due to the poor measurement of their optical properties. The first portion of this presentation will focus on the use of custom-built photoacoustic and cavity ring-down spectrometers to accurately quantify the UV-Vis absorption and extinction properties of aerosols in large-scale laboratory experiments and long-term sampling of ambient aerosols. Moving away from Earth, Titan’s atmosphere exhibits highly diverse chemistry, leading to the formation of aerosols that give Titan its characteristic orange hue. Remote sensing in the infrared allows us to detect specific molecules that play critical roles in Titan’s chemical network. The Cassini mission provided excellent spatial and temporal coverage of infrared observations of Titan’s atmosphere with the CIRS instrument; however, after its retirement in 2017, Earth-based observations of Titan from ground and space-based telescopes gives us the best opportunity for the detection of new species. Utilizing observations from NASA’s SOFIA mission and the Infrared Telescope Facility, we can better constrain the chemistry of key molecules in Titan’s atmosphere and narrow down formation mechanisms of large macromolecules.
Bio
Zachary McQueen is a postdoctoral fellow at NASA Goddard Spaceflight Centre in Greenbelt. During his PhD, Zach studied aerosols in Earth’s atmosphere. His now specialises in the atmosphere of Titan and uses Cassini spacecraft observations to investigate Titan’s atmospheric composition.