A5078068178- Atmospheric chemistry and aerosols
- Atmospheric and Environmental Gas Dynamics
- Atmospheric aerosols and clouds
- Atmospheric Ozone and Climate
- Air Quality and Health Impacts
- Hydrocarbon exploration and reservoir analysis
- Vehicle emissions and performance
- Aeolian processes and effects
- Air Quality Monitoring and Forecasting
- Methane Hydrates and Related Phenomena
- Fire effects on ecosystems
- Toxic Organic Pollutants Impact
- Seismic Waves and Analysis
- Thermochemical Biomass Conversion Processes
- Coal Properties and Utilization
- CO2 Sequestration and Geologic Interactions
- Indoor Air Quality and Microbial Exposure
- Seismic Imaging and Inversion Techniques
- earthquake and tectonic studies
- Geochemistry and Geologic Mapping
- Reservoir Engineering and Simulation Methods
- Seismology and Earthquake Studies
- Spectroscopy and Laser Applications
- Particle Dynamics in Fluid Flows
- Geological Studies and Exploration
University of Wyoming
2015-2024
Ifremer
2023-2024
Université de Bretagne Occidentale
2023-2024
Centre National de la Recherche Scientifique
2023-2024
Purdue University Northwest
2023
Wyoming Department of Education
2014-2022
Institut Universitaire Européen de la Mer
2022
University of Connecticut
2021
California Institute of Technology
2005-2018
Wyoming Space Grant Consortium
2014
Abstract. In this study we compile and present results from the factor analysis of 43 Aerosol Mass Spectrometer (AMS) datasets (27 are reanalyzed in work). The components all sites, when taken together, provide a holistic overview Northern Hemisphere organic aerosol (OA) its evolution atmosphere. At most OA can be separated into oxygenated (OOA), hydrocarbon-like (HOA), sometimes other such as biomass burning (BBOA). We focus on OOA work. many analyses, further deconvolved low-volatility...
Recent work has shown that the atmospheric oxidation of isoprene (2-methyl-1,3-butadiene, C5H8) leads to formation secondary organic aerosol (SOA). In this study, mechanism SOA by photooxidation is comprehensively investigated, measurements yields over a range experimental conditions, namely and NOx concentrations. Hydrogen peroxide used as radical precursor, substantially constraining observed gas-phase chemistry; all dominated OH radical, peroxy radicals (RO2) react only with HO2 (formed...
Recent work in our laboratory has shown that the photooxidation of isoprene (2-methyl-1,3-butadiene, C(5)H(8)) leads to formation secondary organic aerosol (SOA). In current study, chemical composition SOA from over full range NO(x) conditions is investigated through a series controlled chamber experiments. studied using wide experimental techniques: electrospray ionization-mass spectrometry, matrix-assisted laser desorption high-resolution mass online gas chromatography/mass and an...
Abstract. Secondary organic aerosol (SOA) formation from the photooxidation of one monoterpene (α-pinene) and two sesquiterpenes (longifolene aromadendrene) is investigated in Caltech environmental chambers. The effect NOx on SOA for these biogenic hydrocarbons evaluated by performing experiments under varying conditions. dependence α-pinene follows same trend as that observed previously a number precursors, including isoprene, which yield (defined ratio mass formed to parent hydrocarbon...
Recent experimental evidence indicates that heterogeneous chemical reactions play an important role in the gas‐particle partitioning of organic compounds, contributing to formation and growth secondary aerosol atmosphere. Here we present laboratory chamber studies reactive uptake simple carbonyl species (formaldehyde, octanal, trans , ‐2,4‐hexadienal, glyoxal, methylglyoxal, 2,3‐butanedione, 2,4‐pentanedione, glutaraldehyde, hydroxyacetone) onto inorganic aerosol. Gas‐phase compounds aqueous...
The oxidation of isoprene (2‐methyl‐1,3‐butadiene) is known to play a central role in the photochemistry troposphere, but generally not considered lead formation secondary organic aerosol (SOA), due relatively high volatility reaction products. However, chamber studies described here, we measure SOA production from photooxidation under high‐NO x conditions, at significantly lower concentrations than had been observed previously. Mass yields are low (0.9–3.0%), because large emissions, may...
Abstract. Although aliphatic amines have been detected in both urban and rural atmospheric aerosols, little is known about the chemistry leading to particle formation or potential aerosol yields from reactions of gas-phase amines. We present here first systematic study Based on laboratory chamber experiments theoretical calculations, we evaluate reaction OH, ozone, nitric acid with trimethylamine, methylamine, triethylamine, diethylamine, ethylamine, ethanolamine. Entropies for alkylammonium...
Ambient sampling was conducted in Riverside, California during the 2005 Study of Organic Aerosols Riverside to characterize composition and sources organic aerosol using a variety state-of-the-art instrumentation source apportionment techniques. The secondary (SOA) mass is estimated by elemental carbon monoxide tracer methods, water soluble content, chemical balance molecular markers, positive matrix factorization high-resolution spectrometer data. Estimates obtained from each these methods...
Significance Wildfire emissions in the western United States have had increasingly larger impacts on air quality, health, and climate forcing recent decades. However, our understanding of how wildfire plume composition evolves remains incomplete. Particularly, evolution carbonaceous material, including fine particle mass (PM 2.5 ) light-absorbing brown carbon, has remained elusive because limited knowledge about interplay between primary subsequent chemical physical transformations that...
Abstract. Single-scattering albedo (SSA) and absorption Ångström exponent (AAE) are two critical parameters in determining the impact of absorbing aerosol on Earth's radiative balance. Aerosol emitted by biomass burning represent a significant fraction globally, but it remains difficult to accurately predict SSA AAE for aerosol. Black carbon (BC), brown (BrC), non-absorbing coatings all make substantial contributions coefficient cannot be directly predicted based fuel type because they...
Uncertainty in the representation of biomass burning (BB) aerosol composition and optical properties climate models contributes to a range modeled effects on incoming solar radiation. Depending model, top-of-the-atmosphere BB effect can from cooling warming. By relating absorption relative extinction carbonaceous 12 observational datasets nine state-of-the-art Earth system models/chemical transport models, we identify varying degrees overestimation absorptivity by these models. Modifications...
Oxalic acid is often the leading contributor to total dicarboxylic mass in ambient organic aerosol particles. During 2004 International Consortium for Atmospheric Research on Transport and Transformation (ICARTT) field campaign, nine inorganic ions (including SO 4 2− ) five oxalate) were measured board Center Interdisciplinary Remotely Piloted Aircraft Studies (CIRPAS) Twin Otter research aircraft by a particle‐into‐liquid sampler (PILS) during flights over Ohio surrounding areas. Five local...
Recent laboratory studies have demonstrated that isoprene oxidation products can partition to atmospheric aerosols by reacting with condensed phase sulfuric acid, forming low-volatility organosulfate compounds. We identified compounds in free tropospheric single particle mass spectrometry during several airborne field campaigns. One of these organosulfates is as the sulfate ester IEPOX, a second generation product isoprene. The patterns IEPOX ambient data generally followed aerosol acidity...
We report the first joint shipboard and airborne study focused on chemical composition water-uptake behavior of particulate ship emissions. The focuses emissions from main propulsion engine a Post-Panamax class container cruising off central coast California burning heavy fuel oil. Shipboard sampling included micro-orifice uniform deposit impactors (MOUDI) with subsequent off-line analysis, whereas measurements involved number real-time analyzers to characterize plume aerosol, aged few...
Abstract. Biomass burning represents a major global source of aerosols impacting direct radiative forcing and cloud properties. Thus, the goal number current studies involves developing better understanding how chemical composition mixing state biomass evolve during atmospheric aging processes. During Ice in Clouds Experiment-Layer (ICE-L) fall 2007, smoke plumes from two small Wyoming Bureau Land Management prescribed burns were measured by on-line aerosol instrumentation aboard C-130...
Airborne measurements in regions of varying meteorology and pollution are used to quantify the contribution organic acids a mass spectral marker for oxygenated aerosols, m/z 44, total aerosol budget. Organic 44 separately shown exhibit their highest fractions vicinity clouds. The such species is increase as function relative humidity, hygroscopicity (and decreasing fraction), typically greater off California coast versus continental atmospheres studied. Reasons include more efficient...
Abstract. We report an extensive airborne characterization of aerosol downwind a massive bovine source in the San Joaquin Valley (California) on two flights during July 2007. The Center for Interdisciplinary Remotely-Piloted Aircraft Studies (CIRPAS) Twin Otter probed chemical composition, particle size distribution, mixing state, sub- and supersaturated water uptake behavior, light scattering properties, interrelationship between these parameters meteorology. Total PM1.0 levels...
Atmospheric methane emissions from active natural gas production sites in normal operation were quantified using an inverse Gaussian method (EPA's OTM 33a) four major U.S. basins/plays: Upper Green River (UGR, Wyoming), Denver-Julesburg (DJ, Colorado), Uintah (Utah), and Fayetteville (FV, Arkansas). In DJ, Uintah, FV, 72–83% of total measured 20% the well pads, while UGR highest emitting pads only contributed 54% emissions. The mass emitted as a percent gross produced, termed...
Increased use of hydraulic fracturing ("fracking") in unconventional oil and natural gas (O & NG) development from coal, sandstone, shale deposits the United States (US) has created environmental concerns over water air quality impacts. In this perspective we focus on how production O NG affects quality. We pay particular attention to as type transformed US is set become important rest world. A variety potential emission sources can be spread tens thousands acres a area complicates...
Abstract The initiation of ice in an isolated orographic wave cloud was compared with expectations based on nucleating aerosol concentrations and predictions from new nucleation parameterizations applied a parcel model. Measurements crystal number were found to be good agreement both measured nuclei feeding the clouds determined residual particles collected by counterflow virtual impactor. Using lognormal distributions fitted size chemical compositions, reasonably well predicted 1D model...
Abstract. A recent development in the representation of aerosols climate models is realization that some components organic aerosol (OA), emitted from biomass and biofuel burning, can have a significant contribution to shortwave radiation absorption atmosphere. The absorbing fraction OA referred as brown carbon (BrC). This study introduces one first implementations BrC into Community Atmosphere Model version 5 (CAM5), using parameterization for absorptivity described Saleh et al. (2014)....
Abstract. A wide range of globally significant biomass fuels were burned during the fourth Fire Lab at Missoula Experiment (FLAME-4). multi-channel photoacoustic absorption spectrometer (PAS) measured dry 405, 532, and 660 nm thermally denuded (250 °C) 405 nm. Absorption coefficients broken into contributions from black carbon (BC), brown (BrC), lensing following three different methodologies, with one extreme being a method that assumes thermal denuder effectively removes organics other...
Methane emission fluxes were estimated for 71 oil and gas well pads in the western Permian Basin (Delaware Basin), using a mobile laboratory an inverse Gaussian dispersion method (OTM 33A). Sites with emissions that below detection limit (BDL) OTM 33A recorded included sample. Average rate per site was by bootstrapping maximum likelihood best log-normal fit. had to be split into "complex" (sites liquid storage tanks and/or compressors) "simple" only wellheads/pump jacks/separators)...
This study presents the results of a campaign that estimated methane emissions at 268 gas production facilities in Fayetteville shale play using onsite measurements (261 facilities) and two downwind methods – dual tracer flux ratio method (Tracer Facility Estimate TFE, 17 EPA Other Test Method 33a (OTM33A OFE, 50 facilities). A estimate (SOE) for each facility was developed by combining direct simulation unmeasured emission sources, operator activity data from literature. The SOE spans 0–403...