Robert A. Harley
Carl W. Johnson Professor of Civil and Environmental Engineering
Department of Civil and Environmental Engineering, 760 Davis Hall
University of California, Berkeley, CA 94720-1710 USA
Robert 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
Harley's research focuses on air quality and sustainable transportation;
he is an author of over 100 papers published
in peer-reviewed scientific journals.
He is the inaugural holder of the Carl W. Johnson Endowed Chair
in Civil and Environmental Engineering at Berkeley, awarded in recognition of his record of
scholarship and university and professional service.
Harley has also received the National Science Foundation's
young investigator (CAREER) award, and he serves as a Co-Editor of Atmospheric Chemistry and Physics.
Harley has been a visiting scientist
at the University of Colorado / NOAA Aeronomy Lab
in Boulder (1999-2000) and at the Max Planck Institute for Chemistry in Mainz, Germany (2011).
He is also a Faculty Research Scientist
at Lawrence Berkeley
National Laboratory, a U.S. Department of Energy science lab adjacent to campus.
Courses I have taught at Berkeley include
- E 7 (freshman level), Introduction to Computer Programming for Scientists and Engineers.
Elements of procedural and object-oriented programming. Induction, iteration, and recursion. Real functions and floating-point computations for engineering analysis. Introduction to data structures. Representative examples are drawn from mathematics, science, and engineering. The course uses the MATLAB programming language.
- CEE 11 (sophomore level), Engineered Systems and Sustainability.
An introduction to key engineered systems (e.g., energy, water supply, buildings, transportation)
and their environmental impacts. Basic principles of environmental science needed to understand
natural processes as they are influenced by human activities. Overview of concepts and methods of
sustainability analysis. Critical evaluation of engineering approaches to address sustainability.
- CEE 100 (junior level), Elementary Fluid Mechanics.
Principles of mechanics as applied to the statics and dynamics of incompressible fluids; open channel flow,
fluid measurements, forces on submerged objects, pumps, turbines. Individual laboratory experiments
conducted by the student.
- CEE 218A (graduate level), Air Quality Engineering.
Quantitative overview of the characterization and control of air pollution problems. Summary of fundamental
chemical and physical processes governing pollutant behavior. Analysis of key elements of the air pollution
system: sources and control techniques, atmospheric transformation, atmospheric transport, modeling, and
air quality management.
- CEE 218C (graduate level), Air Pollution Modeling.
Theory and practice of mathematical air quality modeling. Modeling atmospheric chemical transformation
processes. Effects of uncertainty in model parameters on predictions. Review of atmospheric diffusion
theory and boundary layer meteorology. Dispersion modeling. Combining chemistry and transport.
Teaching Schedule 2018-19
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|Fall 2018||CEE 218A||Air Quality Engineering||MWF 2-3|
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.
Some 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 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, 58, 65, 70).
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,
An example of research on this topic 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.
A presentation file titled "SMOG: The Movie" posted
an animated series of 24 hourly ozone maps for Southern
California, along with a few introductory slides summarizing
motivation and key features of mathematical models for photochemical smog.
Time Series Analysis
Analysis 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, 56). We use receptor-based models
together with 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.
An 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:
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.
The transportation sector involves movement of both passengers and
freight. This sector currently relies on
petroleum-derived fuels such as gasoline and diesel.
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 improved emission control
technologies and gasoline reformulation on vehicle emissions
(refs 11, 20-21, 52, 55, 59). While there has been major
progress in control of emissions from gasoline-powered cars and
light trucks, efforts to control emissions from large trucks
and off-road diesel engines have not yet advanced so far.
I have also been a lead developer of the "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 or per unit time (refs 10, 15, 17, 22, 31, 33, 48, 67, 73).
Emission rates for many pollutants (e.g., CO, NOx, as well as CO2 of course)
vary less over wide ranges of vehicle weight
and driving conditions when normalized to fuel consumption (ref 42).
This line of research has contributed to policy-relevant revisions in national and
state-level air pollution emission inventories.
The freight transport sector relies heavily on diesel fuel,
in contrast to passenger travel where gasoline is the dominant fuel.
My research group has been working to describe the amount of diesel-related
air pollution (previous estimates were flawed in various ways), and the
spatial and temporal patterns of those emissions
(refs 16-17, 24-25, 31, 48, 55, 59, 62, 71, 72, 76).
Advanced diesel emission controls such as continuously
regenerating particle traps have been installed on new
engines as standard equipment since 2007,
and have been retrofit on some older engines as well. Control of diesel emissions in
the freight transport sector continues to raise many challenging
technical and policy questions.
Mobile lab used to measure Port truck emissions
We are now using the Port of Oakland as a laboratory
for studying coming statewide and national changes in diesel engine emissions.
Because of the large numbers of marine, locomotive, and heavy truck engines
operating in and around the Port, there are extra concerns about
exposure to diesel exhaust in the surrounding community.
We reported on the effects of an early clean-up effort to replace or install
exhaust filters on Port trucks
(Dallmann et al., ref. 76).
A non-technical summary providing more background on this issue and a
summary of research findings is available:
Berkeley Transportation Letter (Winter 2012 edition).
A paper by
Millstein and Harley (ref. 67) has
influenced policy on the control of
emissions from off-road diesel-powered construction equipment
such as bulldozers and backhoes. The scale of impact is on the order of one billion dollars statewide in
California. Previous emission estimates for nitrogen oxides (NOx) and exhaust particulate matter (PM)
from this sector were too high (see our paper for details).
Rules that would have required retrofit or replacement
of older in-use construction equipment/engines have been revised,
and will take effect more gradually. These policy changes followed from
different counting methods being used to estimate emissions, and
also due to the weak economy.
Graduate Student Advising
Current Ph.D. Students
- Regan Patterson (B.S. in Chemical Engineering, UCLA)
- Sofia Hamilton (B.S. in Civil and Environmental Engineering, UC Berkeley)
Completed Ph.D. Dissertations
- Tom Kirchstetter (B.S. in Atmospheric Science and Math, SUNY Albany; UC Berkeley Ph.D. 1998)
Impact of reformulated fuels on motor vehicle emissions
- Brett Singer (B.S. in Mechanical Engineering, Temple University; UC Berkeley Ph.D. 1998)
A fuel-based approach to estimating motor vehicle exhaust
- Doug Black (B.S. in Electrical Engineering, University of Michigan; UC Berkeley Ph.D. 2000)
Development and application of a sensor for real-time
microenvironmental and personal ozone measurements
- Linsey Marr (B.S. in Engineering Science, Harvard; UC Berkeley Ph.D. 2002)
Changes in ozone sensitivity to precursor emissions on
diurnal, weekly, and decadal time scales
- Andrew Kean (B.S. in Mechanical Engineering, Cooper Union; UC Berkeley Ph.D. 2002)
Effects of vehicle speed and engine load on emissions from in-use light-duty vehicles
- Phil Martien (B.A. in Physics, UC Santa Cruz; B.S. in Environmental
Engineering, Humboldt State; UC Berkeley Ph.D. 2004)
Forward and adjoint sensitivity analysis in Eulerian photochemical air quality models
- George Ban-Weiss (B.S. in Mechanical Engineering, UC Berkeley; UC
Berkeley Ph.D. 2008)
Characterization of gas- and particle-phase emissions from on-road motor
- Ling Jin (B.S. in Physical Geography, Peking University; UC Berkeley
A seasonal perspective on regional air quality in central
- Dev Millstein (B.S. in Economics, Vassar College;
UC Berkeley Ph.D. 2009)
Air quality responses to changes in black carbon and nitrogen oxide
- Drew Gentner (B.S. in Chemical and Environmental Engineering,
Northwestern University; UC Berkeley Ph.D. 2012)
Gas-phase organic carbon and tropospheric pollution: sources, emissions, and implications for air quality
- Juli Rubin (B.S. in Civil and Environmental Engineering, Cornell
University; UC Berkeley Ph.D. 2012)
Investigation of aerosol sources, lifetime and radiative forcing
through multi-instrument data assimilation
- Tim Dallmann (B.S. in Civil and Environmental Engineering, University
of Wisconsin; UC Berkeley Ph.D. 2013)
Evaluation of mobile source emissions and trends
- Sharon Shearer (B.S. in Civil and Environmental Engineering, University
of Texas at Austin; UC Berkeley Ph.D. 2013)
An improved chemical mechanism for photochemical air quality modeling
- Brian McDonald (B.S. in Civil and Environmental Engineering, Virginia Tech; UC Berkeley Ph.D. 2014)
High-resolution mapping and long-term trends for motor vehicle emissions
- Ivy Tao (B.S. in Physics, Bryn Mawr/Haverford College; UC Berkeley Ph.D. 2016)
Changes in mobile source emissions and ambient air quality in California
- Lucas Bastien (B.S. in Energy and Environmental Engineering,
Institut National des Sciences Appliquées, Lyon, France; UC Berkeley Ph.D. 2016)
Adjoint sensitivity analysis of air pollution problems
- Chelsea Preble (B.S. in Environmental Science, UC Berkeley; UC Berkeley Ph.D. 2017)
Effects of advanced after-treatment control technologies on heavy-duty diesel truck emissions
- Matthew Vannucci (B.S. in Physics, Rutgers University; UC Berkeley Ph.D. 2018)
Human-centric indoor air quality