A5065801991- Atmospheric chemistry and aerosols
- Atmospheric Ozone and Climate
- Atmospheric aerosols and clouds
- Atmospheric and Environmental Gas Dynamics
- Air Quality and Health Impacts
- Neonatal and fetal brain pathology
- Vehicle emissions and performance
- Blind Source Separation Techniques
- Ionosphere and magnetosphere dynamics
- Advanced Aircraft Design and Technologies
- Cyclone Separators and Fluid Dynamics
- Substance Abuse Treatment and Outcomes
- Air Quality Monitoring and Forecasting
- Particle Dynamics in Fluid Flows
- Homelessness and Social Issues
- Atomic and Subatomic Physics Research
- EEG and Brain-Computer Interfaces
- Groundwater flow and contamination studies
- Advanced MEMS and NEMS Technologies
- Opioid Use Disorder Treatment
- Spacecraft and Cryogenic Technologies
- Mechanical and Optical Resonators
- Astro and Planetary Science
- Climate Change and Geoengineering
- Wind and Air Flow Studies
Barwon Health
2025
Eastern Health
2017-2025
University of Cincinnati
1978-2022
Monash University
2019-2020
University of Denver
2008-2019
University of Arkansas at Little Rock
2005-2019
Curtin University
2016-2017
Quintessa (United Kingdom)
2009-2016
Digital Science Technologies (United States)
2015
University of Guelph
2014
A single‐particle soot photometer (SP2) was flown on a NASA WB‐57F high‐altitude research aircraft in November 2004 from Houston, Texas. The SP2 uses laser‐induced incandescence to detect individual black carbon (BC) particles an air sample the mass range of ∼3–300 fg (∼0.15–0.7 μm volume equivalent diameter). Scattered light is used size remaining non‐BC aerosols ∼0.17–0.7 diameter. We present profiles both aerosol types boundary layer lower stratosphere two midlatitude flights. Results for...
Interest in stratospheric aerosol and its role climate have increased over the last decade due to observed increase since 2000 potential for changes sulfur cycle induced by change. This review provides an overview about advances research comprehensive assessment of was published 2006. A crucial development 2006 is substantial improvement agreement between situ space-based inferences properties during volcanically quiescent periods. Furthermore, new measurement systems techniques, both space...
Unexpectedly high concentrations of ultrafine particles were observed over a wide range latitudes in the upper troposphere and lower stratosphere. Particle number size distributions simulated by numerical model ion-induced nucleation, constrained measured thermodynamic data atmospheric key species, consistent with observations. These findings indicate that, at typical stratosphere conditions, are formed this nucleation process grow to measurable sizes sufficient sun exposure low preexisting...
Black carbon (BC) is the dominant aerosol absorber of solar radiation in atmosphere and an important component anthropogenic climate forcing. BC's role strongly dependent on its physical state, which can influence way that BC particles may act as ice cloud nuclei, well they interact with radiation. In situ measurements made a single‐particle soot photometer flown NASA high‐altitude research aircraft show mass size individual tropics, their propensity to be found mixed additional materials....
Large particles containing nitric acid (HNO3) were observed in the 1999/2000 Arctic winter stratosphere. These situ observations made over a large altitude range (16 to 21 kilometers) and horizontal extent (1800 on several airborne sampling flights during period of weeks. With diameters 10 20 micrometers, these sedimenting have significant potential denitrify lower A microphysical model trihydrate is able simulate growth sedimentation sizes stratosphere, but nucleation process not yet known....
Measurements of total reactive nitrogen (NO y ), water, and aerosol were made as part the Airborne Antarctic Ozone Experiment during August September 1987. The measurements using instruments located on board NASA ER‐2 aircraft, which conducted 12 flights over continent, reaching pressure altitudes 20 km at 72°S latitude. data presented here focus a flight polar stratospheric cloud (PSC) was encountered, containing concentrations 0.8‐ to 2.6‐μm diameter particles greater than 1 cm −3 ....
Atmospheric measurements and numerical calculations described here indicate that binary homogeneous nucleation of H 2 SO 4 -H O particles occurs in the upper tropical troposphere. Particle concentrations decrease with increasing altitude above tropopause as a result coagulation during upward air transport produced by stratospheric circulations. During extended periods time volcanic eruptions do not strongly influence particle number concentrations, formed troposphere provide nuclei upon...
Emission indices of reactive gases and particles were determined from measurements in the exhaust plume a Concorde aircraft cruising at supersonic speeds stratosphere. Values for NO x (sum 2 ) agree well with ground-based estimates. Measurements HO indicate limited role nitric acid plume. The large number submicrometer measured implies efficient conversion fuel sulfur to sulfuric engine or emission. A new fleet similar particle emissions would significantly increase stratospheric aerosol...
Abstract. Aerosol composition was measured by the NOAA single-particle mass spectrometer (PALMS) aboard NASA WB-57 high altitude aircraft platform during two Aura Validation Experiment (AVE) campaigns based in Costa Rica 2004 and 2006. These studies yielded most complete set of aerosol measurements to date throughout tropical tropopause layer (TTL) lower stratosphere. We describe properties atmosphere use tracers examine particle sources, role recent convection, cirrus-forming potential TTL....
Abstract Recent instrumentation can distinguish various types of aerosol particles in the stratosphere and determine their relative abundance. In background lower between major volcanic eruptions, most are either relatively pure sulphuric acid, acid with material from ablated meteoroids or mixed organic‐sulphate that originated troposphere. The meteoritic iron magnesium appear to be dissolved whereas aluminum silicon inclusions. Most stratospheric mass is liquid associated water, but a large...
Abstract. Single-particle mass spectrometry (SPMS) instruments characterize the composition of individual aerosol particles in real time. Their fundamental ability to differentiate externally mixed particle types that constitute atmospheric population enables a unique perspective into sources and transformation. However, quantitative measurements by SPMS systems are inherently problematic. We introduce new technique combines collocated size-resolved absolute concentrations on aircraft...
ER‐2 aircraft observations of OH and HO 2 concentrations in the upper troposphere during NASA/STRAT campaign are interpreted using a photochemical model constrained by local O 3 , H O, NO, CO, hydrocarbons, albedo overhead ozone column. We find that reaction Q(¹D) + is minor compared to acetone photolysis as primary source x (= peroxy radicals) troposphere. Calculations diel steady state agree with observed lower stratosphere and, for some flights, However, other flights troposphere,...
We observed a plume of air highly enriched in carbon monoxide and particles the stratosphere at altitudes up to 15.8 km. It can be unambiguously attributed North American forest fires. This demonstrates an extra‐tropical direct transport path from planetary boundary layer several kilometers deep into stratosphere, which is not fully captured by large‐scale atmospheric models. process indicates that stratospheric ozone could sensitive changes burning associated with climatic warming.
Atmospheric particles were collected in the midlatitude upper troposphere (UT) and lower stratosphere (LS) by inertial impaction for subsequent electron microscopy individual particle elemental analysis. More than 97% of analyzed on impactor substrates exposed LS contained only O S detectable quantites; these are believed to be acidic sulfate. Nonsulfate materials seen remaining included soot, other c‐rich substances crustal materials. Although not predominantly sulfate, usually carried a...
In situ measurements of chlorine monoxide, bromine and ozone are extrapolated globally, with the use meteorological tracers, to infer loss rates for in Arctic lower stratosphere during Airborne Stratospheric Expedition II (AASE II) winter 1991-1992. The analysis indicates removal 15 20 percent ambient because elevated concentrations monoxide monoxide. Observations AASE define attributable reaction nitrogen dioxide (produced by photolysis nitric acid) production hydrochloric acid. Ozone...
Imaging and light scattering instruments were used during the January/February 1987 STEP Tropical Experiment at Darwin, Australia, to measure ice crystal size distributions in tops of tropical cumulonimbus anvils associated with cyclones related cloud systems. Two covered particles from 0.1‐μm 78‐μm diameter. Particles larger than 50‐μm diameter imaged a two‐dimensional Grey optical array imaging probe. The measurements made altitudes ranging 13 18 km temperatures −60° −90°C. Additional...
Abstract. Recent in situ measurements at tropical tropopause temperatures as low 187 K indicate supersaturations with respect to ice exceeding 100% little or no present. In contrast, models used simulate cloud formation near the assume a supersaturation threshold for nucleation of about 65% based on laboratory aqueous aerosol freezing. The high reported here, along simulations assuming plausible range temperature histories sampled air mass, that vast majority aerosols this flight must have...
Particle size distributions and gas‐phase particle precursors tracer species were measured aboard an aircraft in the plumes downwind from industrial urban sources vicinity of Houston, TX during daytime late August early September 2000. Plumes originating Parish gas‐fired coal‐fired power plant, petrochemical industries along Houston ship channel, facilities near Gulf coast, center studied. Most mass flux advected came electrical utilities at periphery city rather than core. In SO 2 ‐rich...
In situ analyses with a laser ionization mass spectrometer have shown that large fraction of aerosols in the bottom few kilometers stratosphere contain small amounts mercury (1). Electron microscopy particles collected near tropopause has also detected mercury. The distribution onto many particles, including those less than 20 nm diameter, indicates is from local condensation compounds rather transport mercury-rich surface sources. Although results are only semiquantitative, they suggest...
In previous publications (McMurry and Wilson, 1982; McMurry et al., 1981), techniques for determining the relative contributions of gas phase liquid reactions to secondary ambient aerosol formation have been described. this paper these methods are applied more recent data acquired during 1980 Environmental Protection Agency PEPE‐NEROS study near Columbus, Ohio. It is shown that tend be most important mechanism sulfate humidities greater than 75%, while predominant at lower humidities. either...
Abstract. New particle formation (NPF), which generates nucleation mode aerosol, was observed in the tropical Upper Troposphere (UT) and Tropical Tropopause Layer (TTL) by situ airborne measurements over South America (January–March 2005), Australia (November–December West Africa (August 2006) Central (2004–2007). Particularly intense NPF found at bottom of TTL. Measurements with a set condensation counters (CPCs) different dp50 (50% lower size detection efficiency diameter or "cut-off...