Grant to allow study of famous blue haze

| July 1, 2013

A view from the Blue Ridge Parkway shows the haze that colors the mountains when seen from a distance.

Assistant professor of environmental science Tom O’Halloran has received a grant from the Thomas F. and Kate Miller Jeffress Memorial Trust to conduct research on the iconic haze that gives the Blue Ridge Mountains their name.

“I’m essentially examining the Blue Ridge Haze and trying to determine what controls its formation, and whether it affects cloud properties or regional climate,” he says.

The Jeffress Trust provides $100,000 awards to seed projects to “benefit the people of Virginia, in and devoted to, research in chemical, medical or other scientific fields.” O’Halloran plans to purchase new air quality equipment to detect atmospheric aerosols — particles suspended in the gases that make up air. There will also be funding to hire a student researcher in the summer of 2014 during a planned field campaign to collect data.

Tom O’Halloran

This fall, senior environmental science majors will spend much of their time in O’Halloran’s advanced lab course installing the equipment at an existing weather station. He wants to be ready to turn everything on by the spring semester.

The area of study is concentrated on Sweet Briar’s campus, which lies on the eastern slopes of the Blue Ridge Mountains. The College’s 3,250 acres contain more than 1,500 acres of predominantly oak forest. This forest type is among the strongest emitters of natural volatile organic compounds, known as VOCs, in the world, he says.

Natural VOCs combine with local and upwind sources of air pollution to produce the summer hazes that are typical in the southeastern United States. These kinds of atmospheric aerosols can be harmful to human health and they reduce visibility. They also can either cool or warm the climate depending on their size, chemical composition and location in the atmosphere. However, these processes are not well understood and O’Halloran hopes to shed new light on the factors controlling them through his research.

The new gas and particle sensors will help determine the aerosols’ composition. Sophisticated modeling techniques and statistical analysis will be used to predict their formation in the future. He is also trying to understand the haze’s “radiative” effect — how much sunlight passes through to either heat or cool the land and air. Some aerosols may also attract water, impacting the radiative properties of clouds and their ability to produce precipitation.

The Jeffress-funded research builds on O’Halloran’s doctoral work at the University of Virginia. He joined Sweet Briar’s faculty in 2011 after receiving his Ph.D. in 2008 and completing postdoctoral research at Oregon State University, where he examined the impacts of forest disturbances, such as fire and insect outbreaks, on the carbon cycle. As a specialist in atmospheric science, O’Halloran is interested in many of the physical and chemical processes comprising surface-atmosphere interactions, and particularly those involving forests.

Jennifer McManamay

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Category: Environmental Science