Atmospheric & Environmental Chemistry

The Center for Atmospheric and Environmental Chemistry performs laboratory and field experiments to study the sources, sinks and chemical transformations of gas phase molecules in the Earth’s atmosphere and other environments.  Techniques that we apply include Tunable Infrared Laser Differential Absorption Spectroscopy (TILDAS) using long path length astigmatic multi-pass cells, discharge flow chemical kinetics, the design and application of various mathematical models, and several advanced gas flux measurement techniques (eddy covariance, gradient flux, tracer release and others).  A key research tool for many of our field projects is the Aerodyne Mobile Laboratory which allows us to perform remote field measurements with state of the art laboratory tools.  Our research and development activities are supported by government agencies, private companies and private sector research consortia.

Government sponsors include: the National Aeronautics and Space Administration, the National Oceanic and Atmospheric Administration, the Department of Energy, the National Science Foundation, the Environmental Protection Agency, the Department of Agriculture and the U.S. Geological Survey.

Dr. Scott C. Herndon
Ph. D., Physical Chemistry, University of Colorado

Dr. Herndon is a physical chemist and Director of the Center for Atmospheric and Environmental Chemistry at Aerodyne Research, Inc. Since joining Aerodyne in 1999, his research interests have focused on the development and utilization of laboratory and field trace gas and fine particle instrumentation, together with modeling studies, to characterize and elucidate atmospheric processes relevant to stratospheric ozone depletion, urban and regional air quality and climate change.  He has led over 20 field measurement campaigns to characterize and quantify air pollutant emission sources and map ambient pollution concentrations using suites of advanced, real-time spectroscopic and mass spectrometric instrumentation deployed on the Aerodyne Mobile Laboratory and on a range of research aircraft and ships. Most recently Dr. Herndon has developed an improved dual tracer release ratio method to quantify methane emissions from oil and gas production and transmission facilities and other sources in the US and Mexico. He is the author or co-author of over 50 archival publications addressing atmospheric science and physical chemistry issues.

J. Barry McManus

Ph.D., Physics, Massachusetts Institute of Technology

Dr. McManus has expertise in optical instrumentation design and applications to atmospheric trace gas measurements. He has extensive experience in field measurements of atmospheric trace gases and leads the ARI programs in methane emissions measurements from man-made sources. His expertise extends to tunable diode laser instrumentation and advanced optical designs for ground-based and aircraft borne trace gas detection systems using the ARI Astigmatic Multipass Absorption Cell, which he co-developed.

Dr. David D. Nelson

Ph.D., Chemical Physics, Harvard University

Dr. Nelson is President and CEO of Aerodyne Research, Inc. He is an expert in molecular spectroscopy, chemical kinetics and the detection of gas phase molecules. He is a co-developer of Aerodyne’s quantum cascade laser trace gas monitors and author of the TDLWintel data acquisition and analysis software. His research interests include chemistry related to ozone depletion and global climate change, the study of regional air pollution, the use of isotopes as environmental tracers and the development of increasingly sensitive trace gas monitors. Dr. Nelson is a Fellow of the Optical Society of America.

Joanne H. Shorter

Ph.D., Physical Chemistry, Massachusetts Institute of Technology

Dr. Shorter’s expertise is in the area of molecular spectroscopy and its application to atmospheric trace gas detection. She has extensive experience in the development and deployment of sensitive laser based instruments for a range of applications including atmospheric monitoring, breath analysis for biomarker detection for medical applications, and quantitative molecular spectroscopy.

Dr. Joseph R. Roscioli
Ph.D., Physical Chemistry, Yale University

Dr. Roscioli is involved in field studies of atmospheric trace gas concentrations for the Aerodyne Mobile Laboratory, as well as the design and development of trace gas measurement instrumentation.  Previous work has included quantum state-resolved direct absorption spectroscopy and velocity-map imaging of atmospherically-relevant molecules.  Dr. Roscioli has also been involved in the characterization of environmentally-relevant ions and ionic clusters using infrared rare gas predissociation spectroscopy and multi-laser techniques.

Tara I. Yacovitch
Ph.D., Physical Chemistry, University of California at Berkeley

Dr. Yacovitch is a principal scientist at the Center for Atmospheric and Environmental Chemistry, Aerodyne Research, Inc. Her research interests include development and use of trace gas instrumentation, with a focus on ethane and the isotopes of methane. She is also heavily involved in field projects aimed at detecting and quantifying methane emissions from oil and gas source; measuring emission factors from aircraft exhaust; and tracing the photochemistry of ozone formation in urban areas.

Christoph Dyroff

Dr. Dyroff received his Ph.D in Electrical Engineering from the University of Karlsruhe in Germany where he developed laser spectrometers for laboratory and airborne measurements. Together with Peter Werle and the group of Alan Fried at NCAR he was using the Stark effect to suppress optical interference fringes in formaldehyde measurements. He also developed a laser spectrometer to measure isotopologues of water vapor on aircraft. He continued his research at Karlsruhe Institute of Technology where he built and deployed several laser spectrometers on passenger and research aircraft. Christoph is able to provide customer support in the UK timezone.

Elizabeth Lunny

Ph.D. candidate in physical chemistry at the California Institute of Technology (Caltech)

Dr. Lunny has experience developing state of the art precision laser methods for high resolution spectroscopy. She has used cavity ring-down and photoacoustic spectroscopy for laboratory based oxygen and carbon dioxide measurements in support of OCO-2, a NASA satellite measuring the global sources and sinks of carbon dioxide.

Conner Daube
B. A., Chemistry, Clark University

Mr. Daube joined Aerodyne as a Research Associate in 2015.  He graduated with a B.A. in Chemistry from Clark University.  His primary role involves engaging in field studies performing gas phase measurements through the Aerodyne Mobile Laboratory.

Mike Agnese
M.S., Mechanical Engineering, Boston University

Mr. Agnese returned to Aerodyne Research in 2011. He has experience in opto-mechanical design, design for high vacuum systems, and vibration simulation and testing. He will be concentrating on development and construction of Quantum Cascade Laser Trace Gas Detector system. Previously he worked in CEPT on the Miniature Internal Combustion Engine program.

Michael Moore

B. S. Electrical Engineering, University of Massachusetts

Mr. Moore joined Aerodyne Research in 2012 as an Electrical Engineer and is a member of the team that produces Aerodyne’s Quantum Cascade Laser Trace Gas Monitors. His main responsibilities include the design, construction, testing, and troubleshooting of its various systems, as well instrument technical support.

Stanley C. Huang

B.S., Electronics Engineering, Wentworth Institute of Technology

Mr. Huang joined Aerodyne Research as an Assistant Engineer in 2008. His main responsibilities are the construction, testing and trouble shooting of scientific instruments. He is a key member of the team that produces Aerodyne’s Laser Trace Detector systems. His interests and training are in the design of electrical and mechanical systems. He is a Chinese speaker.

Paula Sar-Kroeung

Lowell High School’s General Studies program

Mrs. Sar-Kroeung joined Aerodyne in 2014 as a mechanical assembler. She is a graduate from Lowell High School’s General Studies program and has been in the manufacturing field for over 10 years as a self-taught soldering specialist, having honed her skills at various ISO certified companies. She is currently a member of the team that produces Aerodyne’s Quantum Cascade Laser Trace Detector systems. Her responsibilities include the assembly of the instruments various subsystems.

Rick Weyr

Ph.D., Physics, University of Toronto

Dr. Wehr is a senior scientist in the Center for Atmospheric and Environmental Chemistry, focusing on trace gas instrument diagnostics. His areas of expertise include molecular spectroscopy, optics, atmospheric physics, isotope biogeochemistry, and physiological ecology. His doctoral research concerned the physics of infrared spectral line shapes, and he has spent over a decade studying ecosystem-atmosphere exchanges of carbon dioxide and methane isotopologues.

Matthew Lund

Worcester Polytechnic Institute, B.S. in Physics and Mechanical Engineering

Mr. Lund works at as an Opto-Mechanical Engineer at Aerodyne.

William Long

Massbay Community College, Associates in Environmental Sciences

Mr Long is working in CAEC doing assembly work and training to be a technician.

Field Measurement Services

Aerodyne’s mobile laboratory(ies) and instruments have participated in numerous field campaigns focusing on a great variety of scientific areas.

Neighborhood Mapping for Pollution Impact

The fast-response online measurement methods aboard the mobile laboratory enables us to map spatial gradients of emitted pollutants.

Tracer Release Studies

Tracer release methodology [Roscioli et al., 2015] is used to quantify emissions at industrial facilities like natural gas well pads, compressor stations, dairy farms, and more. These studies rely on releasing small quantities of one or more tracer gases like nitrous oxide (N2O), acetylene (C2H2) or ethane (C2H6) at or near to a facility. The tracer gases co-disperse with any site emissions like methane (CH4), and are measured downwind by the mobile laboratory. The tracer release method allows for accurate and complete facility-scale emission quantification, with typical uncertainties better than 50%.

Fenceline Monitoring and Leak Detection

The mobile laboratory can be operated in “survey mode” for real-time detection and source identification of equipment leaks.

Alternative Platform Deployments:

Some studies require deployment of instrumentation on other vessels, like aircraft, ships or containers. Aerodyne has installed instruments or suites of instruments aboard aircraft and ships of varying sizes.

Research and commercial instruments are installed into the Mobile Laboratory to collect data while in motion for plume characterization, area mapping or portable deployment for photochemistry and transport experiments.

Instruments on the Mobile Laboratory

The Aerodyne Mobile Laboratory has a suite of instrumentation that changes depending on the requirements of the measurement campaign.

Aerodyne-manufactured instruments:

Non-Aerodyne commercially available instruments:

  •     GPS position and GPS compass
  •     2D or 3D anemometers
  •     Commercial systems for measuring NOx, NO

Research-grade instrumentation is often integrated into the mobile laboratory by project collaborators:

And the Mobile Laboratory has been host to numerous research and commercial instruments from collaborators.


Mobile Laboratory Observations of Methane Emissions in the Barnett Shale Region, T. I. Yacovitch, S. C. Herndon, G. Pétron, J. Kofler, D. Lyon, M. S. Zahniser, C. E. Kolb, Environ. Sci. Technol., 49, 7889–7895, 2015.

Constructing a Spatially Resolved Methane Emission Inventory for the Barnett Shale Region, D. R. Lyon, D. Zavala-Araiza, R. A. Alvarez, R. Harriss, V. Palacios, X. Lan, R. Talbot, T. Lavoie, P. Shepson, T. I. Yacovitch, S. C. Herndon, A. J. Marchese, D. Zimmerle, A. L. Robinson, S. P. Hamburg, Environ. Sci. Technol., 49, 8147–8157, 2015.

Atmospheric Emission Characterization of Marcellus Shale Natural Gas Development Sites, J. D. Goetz, C. Floerchinger, E. C. Fortner, J. Wormhoudt, P. Massoli, W. B. Knighton, S. C. Herndon, C. E. Kolb, E. Knipping, S. L. Shaw, P. F. DeCarlo, Environ. Sci. Technol., 49, 7012–7020, 2015.

Methane Emissions from Natural Gas Compressor Stations in the Transmission and Storage Sector: Measurements and Comparisons with the EPA Greenhouse Gas Reporting Program Protocol, R. Subramanian, L. L. Williams, T. L. Vaughn, D. Zimmerle, J. R. Roscioli, S. C. Herndon, T. I. Yacovitch, C. Floerchinger, D. S. Tkacik, A. L. Mitchell, M. R. Sullivan, T. R. Dallmann, A. L. Robinson, Environ. Sci. Technol., 49, 3252-3261, 2015.

Measurements of methane emissions from natural gas gathering facilities and processing plants: measurement methods, J. R. Roscioli, T. I. Yacovitch, C. Floerchinger, A. L. Mitchell, D. S. Tkacik, R. Subramanian, D. M. Martinez, T. L. Vaughn, L. Williams, D. Zimmerle, A. L. Robinson, S. C. Herndon, A. J. Marchese, Atmos. Meas. Tech., 8, 2017-2035, 2015.

Measurements of Methane Emissions from Natural Gas Gathering Facilities and Processing Plants: Measurement Results, A. L. Mitchell, D. S. Tkacik, J. R. Roscioli, S. C. Herndon, T. I. Yacovitch, D. M. Martinez, T. L. Vaughn, L. L. Williams, M. R. Sullivan, C. Floerchinger, M. Omara, R. Subramanian, D. Zimmerle, A. J. Marchese, A. L. Robinson, Environ. Sci. Tech., 49, 3219-3227, 2015.

Measurements of methane emissions from natural gas gathering facilities and processing plants: measurement methods, J. R. Roscioli, T. I. Yacovitch, C. Floerchinger, A. L. Mitchell, D. S. Tkacik, R. Subramanian, D. M. Martinez, T. L. Vaughn, L. Williams, D. Zimmerle,A. L. Robinson, S. C. Herndon, A. J. Marchese, Atmos. Meas. Tech. Discuss., 7, 12357–12406, 2014.

Demonstration of an Ethane Spectrometer for Methane Source Identification, T. Yacovitch, S. C. Herndon, J. R. Roscioli, C. Floerchinger, R. M. McGovern, M. Agnese, G. Pétron, J. Kofler, C. Sweeney, A. Karion, S. A. Conley, E. A. Kort, L. Nähle, M. Fischer, L. Hildebrandt, J. Koeth, J. B. McManus, D. D. Nelson, M. S. Zahniser, C. E. Kolb, Environ. Sci. Technol., 48, 8028-8034, 2014.

Atmospheric CH4 and N2O measurements near Greater Houston area landfills using a QCL-based QEPAS sensor system during DISCOVER-AQ 2013, M. Jahjah, W. Jiang, N. P. Sanchez, W. Ren, P. Patimisco, V. Spagnolo, S. C. Herndon, R. J. Griffin, F. K. Tittel, Opt. Lett. 39, 957-960, 2014.

Online measurements of the emissions of intermediate-volatility and semi-volatile organic compounds from aircraft, E. S. Cross, J. F. Hunter, A. J. Carrasquillo, J. P. Franklin, S. C. Herndon, J. T. Jayne, D. R. Worsnop, R. C. Miake-Lye, and J. H. Kroll, Atmos. Chem. Phys., 13, 7845-7858, 2013.

Detecting fugitive emissions of 1,3-butadiene and styrene from a petrochemical facility: An application of a mobile laboratory and a modified proton transfer reaction mass spectrometer, W. B. Knighton, S. C. Herndon, E. C. Wood, E. C. Fortner, T. B. Onasch, J. Wormhoudt, C. E. Kolb, B. H. Lee, M. Zavala, L. Molina, M. Jones, Industrial & Engineering Chemistry Research, 51, 12674–12684, 2012.

Direct measurement of volatile organic compound emissions from industrial flares using real-time online techniques: Proton transfer reaction mass spectrometry and tunable infrared laser differential absorption spectroscopy, W. B. Knighton, S. C. Herndon, J. F. Franklin, E. C. Wood, J. Wormhoudt, W. Brooks, E. C. Fortner, D. T. Allen, Industrial & Engineering Chemistry Research, 51, 12674–12684, 2012.

Aircraft Emissions of methane and nitrous oxide during the alternative aviation fuel experiment, G. W. Santoni, B. H. Lee, E. C. Wood, S. C. Herndon, R. C. Miake-Lye, S. S. Wofsy, J. B. McManus, D. D. Nelson, M. S. Zahniser, Environ. Sci. Tech. 45, 7075-7082, 2011.