A5002001444- 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
- Smart Materials for Construction
- Odor and Emission Control Technologies
- Water Quality Monitoring and Analysis
- Vehicle emissions and performance
- Plant responses to elevated CO2
- Mercury impact and mitigation studies
- Fire effects on ecosystems
- Lightning and Electromagnetic Phenomena
- Toxic Organic Pollutants Impact
- Calibration and Measurement Techniques
- Ocean Acidification Effects and Responses
- Arctic and Russian Policy Studies
- Indoor Air Quality and Microbial Exposure
- Planetary Science and Exploration
- COVID-19 impact on air quality
- Catalytic Processes in Materials Science
- Pesticide and Herbicide Environmental Studies
- Isotope Analysis in Ecology
- Industrial Gas Emission Control
University of Alaska Fairbanks
2017-2025
National Research Council
2024
Institute of Atmospheric Sciences and Climate
2024
University of Alaska System
2020
Princeton University
2011-2018
NOAA Geophysical Fluid Dynamics Laboratory
2011-2018
National Oceanic and Atmospheric Administration
2012-2017
Harvard University Press
2011-2016
Cooperative Institute for Research in Environmental Sciences
2016
University of Colorado Boulder
2016
Oxidation of biogenic volatile organic compounds (BVOC) by the nitrate radical (NO3) represents one important interactions between anthropogenic emissions related to combustion and natural from biosphere. This interaction has been recognized for more than 3 decades, during which time a large body research emerged laboratory, field, modeling studies. NO3-BVOC reactions influence air quality, climate visibility through regional global budgets reactive nitrogen (particularly nitrates), ozone,...
Abstract. Global models of atmospheric mercury generally assume that gas-phase OH and ozone are the main oxidants converting Hg0 to HgII thus driving deposition ecosystems. However, thermodynamic considerations argue against importance these reactions. We demonstrate here viability atomic bromine (Br) as an alternative oxidant. conduct a global 3-D simulation with GEOS-Chem model assuming Br be sole oxidant (Hg + model) compare previous version OH/O3 model). specify concentration fields...
Abstract. We use a global chemical transport model (GEOS-Chem CTM) to interpret observations of black carbon (BC) and organic aerosol (OA) from the NASA ARCTAS aircraft campaign over North American Arctic in April 2008, as well longer-term records surface air snow (2007–2009). BC emission inventories for America, Europe, Asia are tested by comparison with these source regions. Russian open fires were dominant OA troposphere during but we find that was prevailingly anthropogenic (fossil fuel...
Abstract. Peroxyacetyl nitrate (PAN) formed in the atmospheric oxidation of non-methane volatile organic compounds (NMVOCs) is principal tropospheric reservoir for nitrogen oxide radicals (NOx = NO + NO2). PAN enables transport and release NOx to remote troposphere with major implications global distributions ozone OH, main oxidants. Simulation a challenge models because dependence on vertical as well complex uncertain NMVOC sources chemistry. Here we use an improved representation NMVOCs...
Abstract. The measurement of OH reactivity, the inverse lifetime, provides a powerful tool to investigate atmospheric photochemistry. A new airborne reactivity instrument was designed and deployed for first time on NASA DC-8 aircraft during second phase Intercontinental Chemical Transport Experiment-B (INTEX-B) campaign, which focused Asian pollution outflow over Pacific Ocean based in Hawaii Alaska. measured by adding OH, generated photolyzing water vapor with 185 nm UV light moveable wand,...
Abstract We implement a new isoprene oxidation mechanism in global 3‐D chemical transport model (GEOS‐Chem). Model results are evaluated with observations for ozone, products, and related species from the International Consortium Atmospheric Research on Transport Transformation aircraft campaign over eastern United States summer 2004. The achieves an unbiased simulation of ozone boundary layer free troposphere, reflecting canceling effects recent updates chemistry, bromine HO 2 loss to...
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 understanding of oxidation in forest atmospheres is being challenged by measurements unexpectedly large amounts hydroxyl (OH). A significant number these OH were made laser-induced fluorescence low-pressure detection chambers (called Fluorescence Assay with Gas Expansion (FAGE)) using the Penn State Ground-based Tropospheric Hydrogen Oxides Sensor (GTHOS). We deployed a new chemical removal method to measure parallel traditional FAGE California forest. gives on average only...
Abstract. We use observations from the April 2008 NASA ARCTAS aircraft campaign to North American Arctic, interpreted with a global 3-D chemical transport model (GEOS-Chem), better understand sources and cycling of hydrogen oxide radicals (HOx≡H+OH+peroxy radicals) their reservoirs (HOy≡HOx+peroxides) in springtime Arctic atmosphere. find that standard gas-phase mechanism overestimates observed HO2 H2O2 concentrations. Computation HOx HOy budgets on basis also indicates large missing sink...
Abstract. Formation of organic nitrates (RONO2) during oxidation biogenic volatile compounds (BVOCs: isoprene, monoterpenes) is a significant loss pathway for atmospheric nitrogen oxide radicals (NOx), but the chemistry RONO2 formation and degradation remains uncertain. Here we implement new BVOC mechanism (including updated isoprene chemistry, monoterpene particle uptake RONO2) in GEOS-Chem global chemical transport model with ∼ 25 × km2 resolution over North America. We evaluate using...
Abstract. The hydroperoxyl radical (HO2) is a major precursor of OH and tropospheric ozone. the main atmospheric oxidant, while ozone an important surface pollutant greenhouse gas. Standard gas-phase models for chemistry tend to overestimate observed HO2 concentrations, this has been tentatively attributed heterogeneous uptake by aerosol particles. It generally assumed that involves conversion H2O2, but limited efficacy as sink because H2O2 can photolyze regenerate from there HO2. Joint...
Abstract. The chemical link between isoprene and formaldehyde (HCHO) is a strong, nonlinear function of NOx (i.e., NO + NO2). This relationship linchpin for top-down emission inventory verification from orbital HCHO column observations. It also benchmark overall photochemical mechanism performance with regard to VOC oxidation. Using comprehensive suite airborne in situ observations over the southeast US, we quantify production across urban–rural spectrum. Analysis its major first-generation...
Abstract Air pollution in the Arctic caused by local emission sources is a challenge that important but often overlooked. Local air can be severe and significantly exceed quality standards, impairing public health affecting ecosystems. Specifically wintertime, accumulate under inversion layers. However, neither contributing are well identified quantified nor relevant atmospheric mechanisms forming understood. In summer, boreal forest fires cause high levels of pollution. Despite exposure to...
Abstract We describe the baseline model configuration and simulation characteristics of Geophysical Fluid Dynamics Laboratory (GFDL)'s Atmosphere Model version 4.1 (AM4.1), which builds on developments at GFDL over 2013–2018 for coupled carbon‐chemistry‐climate as part sixth phase Coupled Intercomparison Project. In contrast with GFDL's AM4.0 development effort, focused physical aerosol interactions is used atmospheric component CM4.0, AM4.1 focuses comprehensiveness Earth system...
The Alaskan Layered Pollution And Chemical Analysis (ALPACA) field experiment was a collaborative study designed to improve understanding of pollution sources and chemical processes during winter (cold climate low-photochemical activity), investigate indoor pollution, dispersion as affected by frequent temperature inversions. A number the research goals were motivated questions raised residents Fairbanks, Alaska, where held. This paper describes measurement strategies conditions encountered...
Abstract. Lagrangian tracer simulations are deployed to investigate processes influencing vertical and horizontal dispersion of anthropogenic pollution in Fairbanks, Alaska, during the Alaskan Layered Pollution Chemical Analysis (ALPACA) 2022 field campaign. Simulated concentrations carbon monoxide (CO), sulfur dioxide (SO2), nitrogen oxides (NOx), including surface elevated sources, highest at under very cold stable conditions. enhancements above (50–300 m) mainly attributed power plant...
Abstract. The Mexico City Metropolitan Area (MCMA) study in April 2003 had measurements of many atmospheric constituents, including OH and HO2. It provided the first opportunity to examine oxidation a megacity developing country that has more pollution than typical U.S. European cities. At midday, typically reached 0.35 pptv (~7×106 cm−3), comparable amounts observed cities, but HO2 40 pptv, most reactivity was also measured, even during highly polluted morning rush hour. MCMA's 25 s−1 day...
OH and HO 2 were measured with the Airborne Tropospheric Hydrogen Oxides Sensor (ATHOS) as part of a large measurement suite from NASA DC‐8 aircraft during Intercontinental Chemical Transport Experiment‐A (INTEX‐A). This mission, which was conducted mainly over North America western Atlantic Ocean in summer 2004, an excellent test atmospheric oxidation chemistry. The HOx results INTEX‐A are compared to those previous campaigns for other related measurements INTEX‐A. Throughout troposphere,...
Abstract. We use 2005–2009 satellite observations of formaldehyde (HCHO) columns from the OMI instrument to infer biogenic isoprene emissions at monthly 1 × 1° resolution over African continent. Our work includes new approaches remove biomass burning influences using absorbing aerosol optical depth data (to account for transport fire plumes) and anthropogenic AATSR persistent small-flame fires (gas flaring). The resulting HCHO (ΩHCHO) follow closely distribution vegetation patterns in...
Ozone (O 3 ) and secondary fine particles come from the atmospheric oxidation chemistry that involves hydroxyl radical (OH) hydroperoxyl (HO 2 ), which are together called HO x . Radical precursors such as nitrous acid (HONO) formaldehyde (HCHO) significantly affect budget in urban environments. These chemical processes connect surface anthropogenic natural emissions to local regional air pollution. Using data collected during Study of Houston Atmospheric Precursors (SHARP) spring 2009, we...
Acetone is one of the most abundant carbonyl compounds in atmosphere and it plays an important role atmospheric chemistry. The ocean global acetone budget highly uncertain, with past studies reaching opposite conclusions as to whether a source or sink. Here we use 3-D chemical transport model (GEOS-Chem) simulation evaluate air-sea exchange budget. Inclusion updated (slower) photolysis loss means that large net not needed explain observed marine air. We find fixed seawater concentration 15...
Atmospheric photooxidation of isoprene is an important source secondary organic aerosol (SOA) and there increasing evidence that anthropogenic oxidant emissions can enhance this SOA formation. In work, we use ambient observations organosulfates formed from epoxydiols (IEPOX) methacrylic acid epoxide (MAE) a broad suite chemical measurements to investigate the relative importance nitrogen oxide (NO/NO2) hydroperoxyl (HO2) formation pathways at forested site in California. contrast IEPOX,...
We describe and evaluate atmospheric chemistry in the newly developed Geophysical Fluid Dynamics Laboratory chemistry‐climate model (GFDL AM3) apply it to investigate net impact of preindustrial (PI) present (PD) changes short‐lived pollutant emissions (ozone precursors, sulfur dioxide, carbonaceous aerosols) methane concentration on composition climate forcing. The inclusion online troposphere‐stratosphere interactions, gas‐aerosol chemistry, aerosol‐cloud interactions (including direct...