A5046694694- 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
- Vehicle emissions and performance
- Fire effects on ecosystems
- Methane Hydrates and Related Phenomena
- Advanced Chemical Sensor Technologies
- Hydrocarbon exploration and reservoir analysis
- Marine and coastal ecosystems
- Odor and Emission Control Technologies
- Water Quality Monitoring and Analysis
- Toxic Organic Pollutants Impact
- Coal Properties and Utilization
- Oil Spill Detection and Mitigation
- Ionosphere and magnetosphere dynamics
- Ocean Acidification Effects and Responses
- Energy and Environment Impacts
- Climate variability and models
- Spectroscopy and Laser Applications
- Isotope Analysis in Ecology
- Cryospheric studies and observations
- Geophysics and Gravity Measurements
University of California, Irvine
2015-2024
GGG (France)
2023-2024
Ames Research Center
1992-2022
Langley Research Center
1992-2022
Bay Area Environmental Research Institute
2022
University of California, Santa Cruz
2022
University of California, Santa Barbara
2022
Orbital Research (United States)
2022
University of California, Los Angeles
1997-2020
Universität Innsbruck
2019
Abstract. Understanding and quantifying the global methane (CH4) budget is important for assessing realistic pathways to mitigate climate change. Atmospheric emissions concentrations of CH4 continue increase, making second most human-influenced greenhouse gas in terms forcing, after carbon dioxide (CO2). The relative importance compared CO2 depends on its shorter atmospheric lifetime, stronger warming potential, variations growth rate over past decade, causes which are still debated. Two...
Abstract. The global methane (CH4) budget is becoming an increasingly important component for managing realistic pathways to mitigate climate change. This relevance, due a shorter atmospheric lifetime and stronger warming potential than carbon dioxide, challenged by the still unexplained changes of CH4 over past decade. Emissions concentrations are continuing increase, making second most human-induced greenhouse gas after dioxide. Two major difficulties in reducing uncertainties come from...
Using observations from the Cheeka Peak Observatory in northwestern Washington State during March‐April, 1997, we show that Asian anthropogenic emissions significantly impact concentrations of a large number atmospheric species air arriving to North America spring. Isentropic back‐trajectories can be used identify possible times when this will felt, however trajectories alone are not sufficient indicate presence pollutants. Detailed chemical and meteorological data one these periods (March...
Gas and particle measurements are described for optically thick regional hazes, dominated by aged smoke from biomass burning, in the cerrado rain forested regions of Brazil. The hazes tended to be evenly mixed surface trade wind inversion at 3–4 km altitude. properties gases particles were significantly different those young (<4 min old). As aged, total amount carbon non‐methane hydrocarbon species (C<11) was depleted about one third due transformations into CO 2 , CO, reactive...
Abstract The Community Earth System Model version 2 (CESM2) includes a detailed representation of chemistry throughout the atmosphere in Atmosphere with and Whole Climate configurations. These model configurations use for Ozone Related chemical Tracers (MOZART) family mechanisms, covering troposphere, stratosphere, mesosphere, lower thermosphere. new MOZART tropospheric scheme (T1) has number updates over previous (MOZART‐4) CESM, including improvements to oxidation isoprene terpenes,...
The average worldwide tropospheric mixing ratio of methane has increased by 11% from 1.52 parts per million volume (ppmv) in January 1978 to 1.684 ppmv September 1987, for an increment 0.016 +/- 0.001 year. Within the limits our measurements, global over past decade is consistent either with a linear growth rate year or slight lessening 5 years. No indications were found effect El Niño-Southern Oscillation-El Chichon events 1982-83 on total methane, although severe reductions reported...
We use a continuous 6‐year record (1996–2001) of GOME satellite measurements formaldehyde (HCHO) columns over east and south Asia to improve regional emission estimates reactive nonmethane volatile organic compounds (NMVOCs), including isoprene, alkenes, HCHO, xylenes. Mean monthly HCHO observations are compared simulated from the GEOS‐Chem chemical transport model using state‐of‐science, “bottom‐up” inventories Streets et al. (2003a) for anthropogenic biomass burning emissions Guenther...
Abstract. We analyzed the measurements of ozone (O3) and its precursors made at rural/suburban sites downwind four large Chinese cities – Beijing, Shanghai, Guangzhou Lanzhou, to elucidate their pollution characteristics, regional transport, in situ production, impacts heterogeneous processes. The same measurement techniques observation-based model were used minimize uncertainties comparison results due difference methodologies. All suffered from serious O3 but showed different precursor...
The photochemistry of the troposphere over South Atlantic basin is examined by modeling aircraft observations up to 12‐km altitude taken during TRACE A expedition in September–October 1992. close balance found 0 column between photochemical production and loss O 3 , with net at high altitudes compensating for weak low altitudes. This implies that concentrations 0–12 km can be explained solely situ photochemistry; influx from stratosphere negligible. Simulation H 2 CH OOH, measured aboard...
We use a global three‐dimensional model simulation of atmospheric methanol to examine the consistency between observed concentrations and current understanding sources sinks. Global in include 128 Tg yr −1 from plant growth, 38 reactions CH 3 O 2 with itself other organic peroxy radicals, 23 decay, 13 biomass burning biofuels, 4 vehicles industry. The growth source is factor higher for young than mature leaves. lifetime 7 days; gas‐phase oxidation by OH accounts 63% sink, dry deposition land...
Abstract. This paper presents the first results of measurements trace gases and aerosols at three surface sites in outside Beijing before during 2008 Olympics. The official air pollution index near Olympic Stadium data from our nearby site revealed an obvious association between quality meteorology different responses secondary primary pollutants to control measures. Ambient concentrations vehicle-related nitrogen oxides (NOx) volatile organic compounds (VOCs) urban dropped by 25% 20–45% two...
Acetone (CH 3 COCH ) was found to be the dominant nonmethane organic species present in atmosphere sampled primarily over eastern Canada (0–6 km, 35°–65°N) during ABLE3B (July August 1990). A concentration range of 357 2310 ppt (= 10 −12 v/v) with a mean value 1140±413 measured. Under extremely clean conditions, generally involving Arctic flows, lowest (background) mixing ratios 550±100 were much troposphere studied. Correlations between atmospheric acetone and select such as C 2 H , CO, 8...
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,...
During the NEAQS‐ITCT2k4 campaign in New England, anthropogenic VOCs and CO were measured downwind from York City Boston. The emission ratios of relative to acetylene calculated using a method which ratio VOC with is plotted versus photochemical age. intercept at age zero gives ratio. so determined compared other measurement sets, including data same location 2002, canister samples collected inside Boston, aircraft measurements Los Angeles average urban composition 39 U.S. cities. All...
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 Wildfires emit significant amounts of pollutants that degrade air quality. Plumes from three wildfires in the western U.S. were measured aircraft during Studies Emissions and Atmospheric Composition, Clouds Climate Coupling by Regional Surveys (SEAC 4 RS) Biomass Burning Observation Project (BBOP), both summer 2013. This study reports an extensive set emission factors (EFs) for over 80 gases 5 components submicron particulate matter (PM 1 ) these temperate wildfires. These include...
Airborne measurements of volatile organic compounds (VOCs) were performed during CalNex 2010 (California Research at the Nexus Air Quality and Climate Change) in Los Angeles (LA) basin May–June ITCT2k2 (Intercontinental Transport Chemical Transformation) May 2002. While CO 2 enhancements similar between two years, ΔCO/ΔCO ratio had decreased by about a factor two. The ΔVOC/ΔCO emission ratios stayed relatively constant years. This indicates that, relative to , VOCs LA also since These data...
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...
We use a 3‐D chemical transport model (the GEOS‐Chem CTM) to evaluate global emission inventory for ethane (C 2 H 6 ), with best estimate the source of 13 Tg yr −1 , 8.0 from fossil fuel production, 2.6 biofuel, and 2.4 biomass burning. About 80% is emitted in Northern Hemisphere. The generally provides reasonable unbiased simulation surface air observations, column measurements, aircraft profiles worldwide, including patterns geographical seasonal variability. main bias 20%–30% overestimate...
Detailed airborne, surface, and subsurface chemical measurements, primarily obtained in May June 2010, are used to quantify initial hydrocarbon compositions along different transport pathways (i.e., deep plumes, the surface slick, atmosphere) during Deepwater Horizon oil spill. Atmospheric measurements consistent with a limited area of surfacing oil, implications for leaked mass drop size distributions. The data further suggest relatively little variation leaking composition over time....