Dr. Herndon is a physical chemist and principal scientist in 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.
Aerodyne Mobile Laboratory
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 Mobil Laboratory has a suite of instrumentation that changes depending on the requirements of the measurement campaign.
- GPS position and GPS compass
- Sonic and rotary vane anemometers
- Commercial systems for measuring NOx, NO, NO2
And the Mobile Laboratory has been host to numerous research and commercial instruments from collaborators.
ACRP Projects - Ongoing
The Airport Cooperative Research Program (ACRP) 02-03a, has determined how the aircraft engine emissions of hazardous air pollutants (HAPs) vary with engine state and ambient temperature. This work produced a simple model to quantify HAP emissions inventory estimates under real world conditions. This model allows airport environmental planners to quantify the emissions benefit from proposed changes in airort operational behavior at airports.
The ACRP project 02-17 is underway to characterized the effective particulate emissions from non-engine aircraft sources, such as auxiliary power units, abraded tire (from touchdown smoke) and brake wear.
The ACRP project 02-54 is underway to characterize engine emissions from General Aviation aircraft. The goal of this project is to improve and augment the information available for airport air quality models. Watch a video of an emissions test here.
BEETEX, Houston – 2015 - present
Benzene and other Toxics Exposure (BEE‐TEX) Study is a field study of exposure to and source attribution of the air toxics: benzene, toluene, ethyl benzene and xylenes (BTEX), as well as other hazardous air pollutants (HAPs) such as formaldehyde and 1,3-butadiene. The study is being conducted in 2015 in the Houston Ship Channel where intense industrial sources of BTEX and other HAPs are located in close proximity to residential neighborhoods.
Discover AQ - Houston 2013, Denver – 2014
DISCOVER-AQ is a four-year campaign to improve the use of satellites to monitor air quality for public health and environmental benefit. Through targeted airborne and ground-based observations, DISCOVER-AQ will enable more effective use of current and future satellites to diagnose ground level conditions influencing air quality.
The Mobile Laboratory made ground measurements of gaseous species and particulate matter in Houston in 2013 and in Denver in 2014. An Aerodyne Mini spectrometer was installed aboard the NASA-P3 aircraft in 2015 to measure ethane over the Denver region.
RPSEA - Denver - 2014 - present
RPSEA’s mission is to provide a stewardship role in ensuring the focused research, development and deployment of safe and environmentally sensitive technology that can effectively deliver hydrocarbons from domestic resources to the citizens of the United States. RPSEA has funded a team of scientists to measure emissions from oil and natural gas sources in the Denver area.
The Mobile Laboratory quantified emissions from a variety of methane sources using the dual tracer release method and using Gaussian dispersion simulations.
Front Range Air Pollution and Photochemistry Experiment - Denver – 2014
This is a collaborative effort between the Colorado Department of Public Health and the Environment, the University of Colorado and Colorado State University, UC Berkeley, and other university collaborators, local projects and agencies including local school districts, NASA, NOAA, and NCAR.
There are five aircraft involved. The NASA P-3 is instrumented for comprehensive in-situ measurements, the NASA King Air measures aerosol parameters with a downward looking LIDAR as well as make integrated column measurements of some tracers. The NASA Falcon carries the GeoTASO instrument which measures column amounts of a number of tracers as well. We are also joined by the Mooney TLS aircraft, which measures CH4 and NMHC emissions at low altitude.
The Aerodyne Mobile Laboratory performed ground measurements of emission sources such as oil and natural gas facilities and large cattle feeding operations. An Aerodyne Dual spectrometer was installed aboard the NCAR C-130 Aircraft to measure ammonia and nitric acid. An Aerodyne Mini spectrometer was installed aboard the NASA P-3 to measure ethane.
Methane Research: The 16 Study Series - 2012-2013
Barnett Coordinated Campaign, Dallas /Fort-Worth – 2013
Gathering and Processing, USA – 2013, 2014
Transmission and Storage, USA – 2012, 2013
In 2012, Environmental Defense Fund spearheaded its largest scientific project to date to better understand from where and how much methane is lost across today’s U.S. natural gas supply chain, including production, gathering and processing facilities, gas transmission and storage, local utility distribution, as well as end users utilizing natural gas commercial trucks and refueling stations. Insights from this effort help inform policies and opportunities to minimize these emissions. This collaborative effort involves partnerships with about 100 universities, research institutions and companies. It is divided into 16 distinct projects that range in their scope from estimating methane emissions in a given geographical area or from specific pieces of equipment across the country.
New York City – 2000/2001 & 2009
In the 2000/2001 campaign, the mobile laboratory was directed to chase Metro Transit Authority (MTA) and other passenger bus vehicles over their normal routes and perform emissions characterization. The study was hosted by the site at Queens College. In 2009, the mobile laboratory revisited New York and characterized the combined emissions from the "line source" represented by the highways and examined the impact of these emissions on ambient aerosol loadings as function of distance from the highway.
Mexico City – 2002, 2003, 2006
In Mexico City, the mobile laboratory was used to collect on-road 'mixed fleet' emissions as well as perform dedicated emissions 'chase' sampling for different vehicle types. When not operated on road, the mobile laboatory was used as a portable platform for both gaseous and particulate ambient pollutant measurements. Forecast meteorology was used to position the mobile laboratory at the sites where ozone production was anticipated to be the largest. These campaigns observed a clear and dramatic association of photochemical ozone with urban photochemical secondary organic aerosol production.
Mexicali – 2005
In Mexicali, several fixed point emission sources were characterized, including feed lots, power plant plumes and the emissions from street side food vendors. On road vehicle exhaust emissions were also characterized. Additionally, the mobile laboratory conducted experiments to compare ambient concentration measurements with data from other stations.
APEX and AAFEX – 2004
The APEX and AAFEX campaigns have used the mobile labotory to significantly advance the understanding of aircraft emissions. The work has produced a refined understanding of primary soot, primary condensable organic and sulfate aerosol particulate matter including the processes important in the initial atmospheric dilution of aircraft engine exhaust. This research has also quantified the emissions performance benefits from using alternative fuels in aircraft engines. This work has greatly informed domestic policy and world wide commercial engine emissions certification practices.