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Robert A. Harley Professor of Environmental Engineering Contact Information
TeachingCourses I have taught at Berkeley in recent years include
Teaching Schedule 2007-08
Office Hours (Spring 2008)Tuesdays 1:30-3 PM and Thursdays 11:15-noon in Rm. 667 Davis Hall.Research (Link to Publication List)The atmosphere carries a heavy burden of air pollution, with large contributions to the problem coming from the combustion of coal and petroleum-derived fuels. As a society, we need to evolve towards a more sustainable, environmentally benign approach to meeting growing demands for energy. My research group uses mathematical models and data from field experiments to help understand air pollution problems and related issues in atmospheric chemistry, climate change, and emission source characterization and control.
Atmospheric ModelingSome air pollutants are formed in situ from other precursor emissions by photochemical reactions in the atmosphere. Air pollution problems of this type, including tropospheric ozone and some components of airborne particulate matter, have complex relationships to precursor emissions. We use mathematical models to synthesize understanding of relevant processes that take place in the real atmosphere.I am particularly interested in development and use of diagnostic tools to assess source contributions to air pollutant concentrations, as there are typically multiple source types and regions that contribute to the problem. We quantify model sensitivity and uncertainty with respect to underlying processes and model input data (see Publication List, refs 14, 23, 41, 50-51, 53). We use models to illuminate the reasons for observed atmospheric responses to changes in emissions that occur on various time scales ranging from diurnal to decadal (refs 15, 40, 51). An example of research in this area is the paper by Martien and Harley (2006), Adjoint Sensitivity Analysis for a Three-Dimensional Photochemical Model: Application to Southern California. Environmental Science & Technology 40, 4200-4210.
Time Series AnalysisAnalysis of measured pollutant concentrations provides a complementary perspective to model-based studies. Unfortunately, the signals that we seek to detect are often hard to separate from natural variability in the system that occurs from day to day and on seasonal time scales. Changes in air pollution observed on weekly and decadal time scales may be more readily linked to changes in emissions (refs 38-39, 47-48, 52). We use receptor-based models together with modern online measurement methods to infer, for example, temperature effects on pollutant emissions (ref 49). This is important to understanding the role of day-to-day meteorological variability in affecting air pollution levels, and also in considering possible effects of climate change. We are currently conducting time and frequency domain analyses of particulate matter concentrations to study atmospheric responses to changes in nitrogen oxide and soot emissions.A recent example of research on this topic is the paper by Rubin et al. (2006), Temperature Dependence of Volatile Organic Compound Evaporative Emissions from Motor Vehicles. Journal of Geophysical Research 111, D03305, doi: 10.1029/2005JD006458. See also Marr and Harley (2002), Spectral Analysis of Weekday-Weekend Differences in Ambient Ozone, Nitrogen Oxide, and Non-methane Hydrocarbon Time Series in California. Atmospheric Environment 36, 2327-2335.
Sustainable TransportationThe transportation sector involves movement of both passengers and freight. This sector currently relies on petroleum-derived fuels such as gasoline and diesel. While there has been progress in control of emissions from gasoline-powered cars and light trucks, serious efforts to control emissions from large trucks and off-road diesel engines are only just getting underway. My research group has made a series of field measurements at a California highway tunnel (Caldecott, hwy 24) that document emission trends over time and, in particular, the effects of gasoline reformulation on vehicle emissions (refs 11, 20-21, 52). I affectionately call this field site "Tenure Tunnel" due to it's productivity as a source of highly-cited research papers!We have mapped out a "fuel-based" approach to estimating vehicle emissions, in which vehicle activity is measured by fuel consumption, and emission rates are expressed per unit of fuel burned rather than per km traveled (refs 10, 15, 17, 22, 31, 33, 48). Emission rates for pollutants such as nitrogen oxides (NOx) and carbon monoxide (CO) vary less over wide ranges of vehicle weight and driving conditions when normalized to fuel consumption (ref 42).
The freight transport sector relies heavily on diesel fuel, in contrast to passenger travel where gasoline is the dominant fuel. My research group is tracking the rapid growth of freight transport, and the different activity and emission profiles of diesel vs. gasoline engines (refs 16-17, 24-25, 31, 48, 55). New diesel emission controls such as continuously regenerating particle traps are starting to appear, and are suitable for retrofit on many existing engines as well. Control of diesel emissions in the freight transport sector will continue to raise many challenging technical and policy questions. An example of research on links between the transporation sector and air pollution is the paper by Harley et al. (2005), Changes in Motor Vehicle Emissions on Diurnal to Decadal Time Scales and Effects on Atmospheric Composition. Environmental Science & Technology, 39, 5356-5362.
Biographical SketchRobert Harley is a Professor in the Department of Civil and Environmental Engineering at the University of California, Berkeley, where he has been on the faculty since 1993. He holds a bachelor's degree in Engineering Science (Chemical Engineering option) from the University of Toronto, and both M.S. and Ph.D. in Environmental Engineering Science from the California Institute of Technology (Caltech). Harley's research focuses on air quality and sustainable transportation; he is an author of over 50 papers published in peer-reviewed scientific journals. Harley received the National Science Foundation's young investigator (CAREER) award in 1996, as well as a visiting scientist fellowship (1999-2000) at the University of Colorado / NOAA Aeronomy Lab in Boulder. Harley served for 3 years as Vice Chair of the Civil and Environmental Engineering Department at Berkeley (2001-04), chairing committees that were responsible for undergraduate curriculum and graduate student admissions. He currently serves as Environmental Engineering faculty group leader (2007-08). Harley is also Deputy Department Head for Atmospheric Sciences in the Environmental Energy Technologies Division of Lawrence Berkeley National Laboratory, a U.S. Department of Energy science lab located adjacent to campus.
Graduate Student AdvisingCurrent Ph.D. Students
Completed Ph.D. Dissertations
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