E. C. Apel
A5024667574- Atmospheric chemistry and aerosols
- Atmospheric Ozone and Climate
- Atmospheric and Environmental Gas Dynamics
- Air Quality and Health Impacts
- Air Quality Monitoring and Forecasting
- Atmospheric aerosols and clouds
- Fire effects on ecosystems
- Vehicle emissions and performance
- Advanced Chemical Sensor Technologies
- Ocean Acidification Effects and Responses
- Water Quality Monitoring and Analysis
- Spectroscopy and Laser Applications
- Toxic Organic Pollutants Impact
- Indoor Air Quality and Microbial Exposure
- Mercury impact and mitigation studies
- Plant responses to elevated CO2
- Isotope Analysis in Ecology
- Odor and Emission Control Technologies
- Ionosphere and magnetosphere dynamics
- Marine and coastal ecosystems
- Mass Spectrometry Techniques and Applications
- Advanced Chemical Physics Studies
- Meteorological Phenomena and Simulations
- Laser-induced spectroscopy and plasma
- Wind and Air Flow Studies
NSF National Center for Atmospheric Research
2015-2024
Atmospheric Chemistry Observations & Modeling
2016-2024
University of California, Irvine
1983-2021
University Corporation for Atmospheric Research
2004-2020
NOAA Chemical Sciences Laboratory
2012
University of Colorado System
2011
University of Colorado Boulder
2003-2011
University of California, Berkeley
2008
Purdue University West Lafayette
2001-2007
Washington State University
2001-2007
Abstract. Biomass burning (BB) is a large source of primary and secondary organic aerosols (POA SOA). This study addresses the physical chemical evolution BB aerosols. Firstly, lifetime POA SOA signatures observed with Aerodyne Aerosol Mass Spectrometer are investigated, focusing on measurements at high-latitudes acquired during 2008 NASA ARCTAS mission, in comparison to data from other field studies laboratory aging experiments. The parameter f60, ratio integrated signal m/z 60 total...
Forest emissions of biogenic volatile organic compounds (BVOCs), such as isoprene and other terpenes, play a role in the production tropospheric ozone aerosols. In northern Michigan forest, direct measurement total OH reactivity, which is inverse lifetime, was significantly greater than expected. The difference between measured expected called missing increased with temperature, did emission rates for terpenes BVOCs. These measurements are consistent hypothesis that unknown reactive BVOCs,...
Abstract. MILAGRO (Megacity Initiative: Local And Global Research Observations) is an international collaborative project to examine the behavior and export of atmospheric emissions from a megacity. The Mexico City Metropolitan Area (MCMA) – one world's largest megacities North America's most populous city was selected as case study characterize sources, concentrations, transport, transformation processes gases fine particles emitted MCMA atmosphere evaluate regional global impacts these...
Abstract. We construct a global atmospheric budget for acetaldehyde using 3-D model of chemistry (GEOS-Chem), and use an ensemble observations to evaluate present understanding its sources sinks. Hydrocarbon oxidation provides the largest source in (128 Tg a−1, factor 4 greater than previous estimate), with alkanes, alkenes, ethanol main precursors. There is also minor from isoprene oxidation. updated chemical mechanism GEOS-Chem, photochemical yields are consistent Master Chemical...
Dimethyl sulfide (DMS), emitted from the oceans, is most abundant biological source of sulfur to marine atmosphere. Atmospheric DMS oxidized condensable products that form secondary aerosols affect Earth's radiative balance by scattering solar radiation and serving as cloud condensation nuclei. We report atmospheric discovery a previously unquantified oxidation product, hydroperoxymethyl thioformate (HPMTF, HOOCH2SCHO), identified through global-scale airborne observations demonstrate it be...
Abstract. We determine enhancement ratios for NOx, PAN, and other NOy species from boreal biomass burning using aircraft data obtained during the ARCTAS-B campaign examine impact of these emissions on tropospheric ozone in Arctic. find an initial emission factor NOx 1.06 g NO per kg dry matter (DM) burned, much lower than previous observations plumes, also one third value recommended extratropical fires. Our analysis provides first observational confirmation rapid PAN formation a smoke...
Abstract The Deep Convective Clouds and Chemistry (DC3) field experiment produced an exceptional dataset on thunderstorms, including their dynamical, physical, electrical structures impact the chemical composition of troposphere. gathered detailed information inflow outflow regions midlatitude thunderstorms in northeast Colorado, west Texas to central Oklahoma, northern Alabama. A unique aspect DC3 strategy was locate sample convective a day after active convection order measure...
Abstract Nocturnal dinitrogen pentoxide (N 2 O 5 ) heterogeneous chemistry impacts regional air quality and the distribution lifetime of tropospheric oxidants. Formed from oxidation nitrogen oxides, N is heterogeneously lost to aerosol with a highly variable reaction probability, γ ), dependent on composition ambient conditions. Reaction products include soluble nitrate (HNO 3 or NO − nitryl chloride (ClNO ). We report first‐ever derivations wintertime aircraft measurements in critically...
Wildfires have a significant adverse impact on air quality in the United States (US). To understand potential health impacts of wildfire smoke, many epidemiology studies rely concentrations fine particulate matter (PM) as smoke tracer. However, there are gas-phase hazardous pollutants (HAPs) identified by Environmental Protection Agency (EPA) that also present plumes. Using observations from Western Wildfire Experiment for Cloud Chemistry, Aerosol Absorption, and Nitrogen (WE-CAN), 2018...
Significance Understanding the sources of tropospheric ozone is important for effective air quality management and accurate radiative forcing attribution. Biomass burning emits large quantities precursors to lower atmosphere. This source can drive regional-scale production, but its impact on global poorly constrained. Here, we present unique in situ aircraft observations continental pollution tracers. Ozone enhancements attributable biomass equal or exceed those from urban emissions, a...
Abstract We present emission measurements of volatile organic compounds (VOCs) for western U.S. wildland fires made on the NSF/NCAR C‐130 research aircraft during Western Wildfire Experiment Cloud Chemistry, Aerosol Absorption, and Nitrogen (WE‐CAN) field campaign in summer 2018. VOCs were measured with complementary instruments onboard C‐130, including a proton‐transfer‐reaction time‐of‐flight mass spectrometer (PTR‐ToF‐MS) two gas chromatography (GC)‐based methods. Agreement within...
Abstract This article provides an overview of the NASA Atmospheric Tomography (ATom) mission and a summary selected scientific findings to date. ATom was airborne measurements modeling campaign aimed at characterizing composition chemistry troposphere over most remote regions Pacific, Southern, Atlantic, Arctic Oceans, examining impact anthropogenic natural emissions on global scale. These dominate chemical reactivity are exceptionally important for air quality climate. data provide in situ...
Abstract. Aerosol indirect radiative forcing (IRF), which characterizes how aerosols alter cloud formation and properties, is very sensitive to the preindustrial (PI) aerosol burden. Dimethyl sulfide (DMS), emitted from ocean, a dominant natural precursor of non-sea-salt sulfate in PI pristine present-day (PD) atmospheres. Here we revisit atmospheric oxidation chemistry DMS, particularly under conditions, its impact on IRF. Based previous laboratory studies, expand simplified DMS scheme used...
Abstract We analyze the effects of diurnal cycle fire emissions (DCFE) and plume rise on U.S. air quality using MUSICAv0 (Multi‐Scale Infrastructure for Chemistry Aerosols Version 0) model during FIREX‐AQ (Fire Influence Regional to Global Environments Air Quality) WE‐CAN (Western wildfire Experiment Cloud chemistry, Aerosol absorption Nitrogen) field campaigns. To include DCFE in model, we employ two approaches: a climatology derived from satellite radiative power product. also implemented...
A new configuration of the Community Earth System Model (CESM)/Community Atmosphere with full chemistry (CAM-chem) supporting capability horizontal mesh refinement through use spectral element (SE) dynamical core is developed and called CESM/CAM-chem-SE. Horizontal in CESM/CAM-chem-SE unique novel that pollutants such as ozone are accurately represented at human exposure relevant scales while also directly including global feedbacks. down to ∼14 km over conterminous US (CONUS) beginning...
Abstract. Proton-transfer-reaction time-of-flight mass spectrometry (PTR-ToF-MS) is a technique commonly used to measure ambient volatile organic compounds (VOCs) in urban, rural, and remote environments. PTR-ToF-MS known produce artifacts from ion fragmentation, which complicates the interpretation quantification of key atmospheric VOCs. This study evaluates extent fragmentation other ionization processes impact urban measurements ions typically assigned isoprene (m/z 69, C5H8H+),...
Abstract. Extensive airborne measurements of non-methane organic gases (NMOGs), methane, nitrogen oxides, reduced species, and aerosol emissions from US wild prescribed fires were conducted during the 2019 NOAA/NASA Fire Influence on Regional to Global Environments Air Quality campaign (FIREX-AQ). Here, we report atmospheric enhancement ratios (ERs) inferred emission factors (EFs) for compounds measured board NASA DC-8 research aircraft nine wildfires one fire, which encompass a range...
Results from a tightly constrained photochemical point model for OH and HO 2 are compared to data collected during the Program Research on Oxidants: Photochemistry, Emissions, Transport (PROPHET) summer 1998 intensive campaign held in northern Michigan. The PROPHET was located deciduous forest marked by relatively low NO x levels high isoprene emissions. Detailed budgets presented. is generally unable match measured OH, with observations 2.7 times greater than average. , however, good...
While deformation at the Earth's surface primarily occurs along tectonic plate boundaries, major earthquakes have shaken regions deep within continental interiors. Three of largest (M > 7.5) historic intraplate occurred Indian subcontinent, suggesting possibility significant deformation. We consider velocities determined from new GPS data collected 29 continuous stations and 41 survey‐mode in India between 1995 2007 to find a north‐south shortening rate 0.3 ± 0.05 nanostrain yr −1 , which...
Data obtained during the TRACE‐P experiment is used to evaluate how well CFORS/STEM‐2K1 regional‐scale chemical transport model able represent aircraft observations. Thirty‐one calculated trace gas and aerosol parameters are presented compared in situ data. The regional shown accurately predict many of important features observed. mean values all lowest 1 km predicted within ±30% observed values. correlation coefficients (R) for meteorological found be higher than those species. For example,...
Abstract. Measurements of aerosol composition were made with an Aerodyne High Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) on board the NSF/NCAR C-130 aircraft as part Intercontinental Chemical Transport Experiment Phase B (INTEX-B) field campaign over Eastern Pacific Ocean. The HR-ToF-AMS measurements non-refractory submicron mass are shown to compare well other instrumentation in INTEX-B study. Two case studies described for pollution layers transported across from...
Observations of C 1 ‐C 10 hydrocarbon mixing ratios measured by in situ instrumentation at the La Porte super site during TexAQS 2000 field experiment are reported. The data were compared to a roadway vehicle exhaust signature obtained from canister samples collected Houston Washburn tunnel same summer better understand impact petrochemical emissions hydrocarbons site. It is shown that abundance ethene, propene, 1‐butene, 2 4 alkanes, hexane, cyclohexane, methylcyclohexane, isopropylbenzene,...
Abstract. The MIRAGE-Shanghai experiment was designed to characterize the factors controlling regional air pollution near a Chinese megacity (Shanghai) and conducted during September 2009. This paper provides information on measurements for this study. In order have some deep analysis of measurements, chemical/dynamical model (version 3 Weather Research Forecasting Chemical – WRF-Chemv3) is applied results are intensively compared with evaluate capability calculating pollutants in Shanghai...
Abstract. Observations during the 2006 dry season of highly elevated concentrations cyanides in atmosphere above Mexico City (MC) and surrounding plains demonstrate that biomass burning (BB) significantly impacted air quality region. We find period our measurements, fires contribute more than half organic aerosol mass submicron scattering, one third enhancement benzene, reactive nitrogen, carbon monoxide outflow from plateau. The combination anthropogenic emissions will affect ozone...