A5057217648- Atmospheric chemistry and aerosols
- Atmospheric Ozone and Climate
- Air Quality Monitoring and Forecasting
- Air Quality and Health Impacts
- Atmospheric and Environmental Gas Dynamics
- Spectroscopy and Laser Applications
- Water Quality Monitoring and Analysis
- Catalytic Processes in Materials Science
- Atmospheric aerosols and clouds
- Advanced Chemical Sensor Technologies
- Odor and Emission Control Technologies
- Free Radicals and Antioxidants
- Vehicle emissions and performance
- Photochemistry and Electron Transfer Studies
- Indoor Air Quality and Microbial Exposure
- Analytical Chemistry and Chromatography
- Catalysis and Oxidation Reactions
- Calibration and Measurement Techniques
- Industrial Gas Emission Control
- Mass Spectrometry Techniques and Applications
- Cultural Heritage Materials Analysis
- Mineralogy and Gemology Studies
- Groundwater and Isotope Geochemistry
- Plant responses to elevated CO2
- Nuclear Physics and Applications
Forschungszentrum Jülich
2015-2024
University of Cologne
2022-2024
National Oceanic and Atmospheric Administration
2008-2024
Karlsruhe Institute of Technology
2024
NOAA Chemical Sciences Laboratory
2024
Stadtwerke Jülich (Germany)
2021
Peking University
2021
Institut für Kälte-, Klima- und Energietechnik
2020
Robert Bosch (Germany)
2019
NOAA Earth System Research Laboratory
2008-2013
Going Faster The concentrations of most tropospheric pollutants and trace gases are kept in check by their reactions with hydroxyl radicals (OH). OH is a short-lived, highly reactive species that produced the atmosphere photochemical processes, regenerated chain chemical follows oxidative destruction those molecules. These regeneration mechanisms were thought to be fairly well understood, but now Hofzumahaus et al. (p. 1702 , published online 4 June) present evidence pathway not previously...
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. A comprehensive field campaign was carried out in summer 2014 Wangdu, located the North China Plain. month of continuous OH, HO2 and RO2 measurements achieved. Observations radicals by laser-induced fluorescence (LIF) technique revealed daily maximum concentrations between (5–15) × 106 cm−3, (3–14) 108 cm−3 (3–15) for RO2, respectively. Measured OH reactivities (inverse lifetime) were 10 to 20 s−1 during daytime. The chemical box model RACM 2, including Leuven isoprene mechanism...
Abstract. Ambient OH and HO2 concentrations were measured by laser induced fluorescence (LIF) during the PRIDE-PRD2006 (Program of Regional Integrated Experiments Air Quality over Pearl River Delta, 2006) campaign at a rural site downwind megacity Guangzhou in Southern China. The observed reached daily peak values (15–26) × 106 cm−3 which are among highest so far reported for urban suburban areas. shows consistent high correlation with j(O1D) broad range NOx conditions. cannot be reproduced...
Abstract. The yields of organic nitrates and secondary aerosol (SOA) particle formation were measured for the reaction NO3+β-pinene under dry humid conditions in atmosphere simulation chamber SAPHIR at Research Center Jülich. These experiments conducted low concentrations NO3 (NO3+N2O5<10 ppb) β-pinene (peak~15 ppb), with no seed aerosol. SOA was observed to be prompt substantial (~50% mass yield both 60% RH), highly correlated nitrate formation. gas/aerosol partitioning can simulated...
The Multiple Chamber Aerosol Chemical Aging Study (MUCHACHAS) tested the hypothesis that hydroxyl radical (OH) aging significantly increases concentration of first-generation biogenic secondary organic aerosol (SOA). OH is dominant atmospheric oxidant, and MUCHACHAS employed environmental chambers very different designs, using multiple sources to explore a range chemical conditions potential systematic error. We isolated effect aging, confirming our while observing corresponding changes in...
Abstract. Total atmospheric OH reactivities (kOH) have been measured as reciprocal lifetimes by a newly developed instrument at rural site in the densely populated Pearl River Delta (PRD) Southern China summer 2006. The deployed technique, LP-LIF, uses laser flash photolysis (LP) for artificial generation and laser-induced fluorescence (LIF) to measure time-dependent decay samples of ambient air. observed PRD covered range from 10 s−1 120 s−1, indicating large load chemical reactants. On...
Abstract. Measurements of ambient OH and HO2 radicals were performed by laser induced fluorescence (LIF) during CAREBeijing2006 (Campaigns Air Quality Research in Beijing Surrounding Region 2006) at the suburban site Yufa south summer 2006. On most days, local air chemistry was influenced aged pollution that advected a slow, almost stagnant wind from southern regions. Observed daily concentration maxima range (4–17) × 106 cm−3 for (2–24) 108 (including an estimated interference 25% RO2)....
Abstract. The first wintertime in situ measurements of hydroxyl (OH), hydroperoxy (HO2) and organic peroxy (RO2) radicals (ROx=OH+HO2+RO2) combination with observations total reactivity OH radicals, kOH Beijing are presented. field campaign “Beijing winter finE particle STudy – Oxidation, Nucleation light Extinctions” (BEST-ONE) was conducted at the suburban site Huairou near from January to March 2016. It aimed understand oxidative capacity during elucidate secondary pollutants' formation...
Abstract. We performed measurements of nitrous acid (HONO) during the PRIDE-PRD2006 campaign in Pearl River Delta region 60 km north Guangzhou, China, for 4 weeks June 2006. HONO was measured by a LOPAP in-situ instrument which setup one supersites along with variety instruments measuring hydroxyl radicals, trace gases, aerosols, and meteorological parameters. Maximum diurnal mixing ratios 1–5 ppb were observed nights. found that nighttime build-up can be attributed to heterogeneous NO2...
On a Zeppelin Nitrous acid (HONO) is an important atmospheric trace gas that acts as precursor of tropospheric hydroxyl-radicals (OH), which responsible for the self-cleansing capacity atmosphere and also controls concentrations greenhouse gases, such methane ozone. How HONO made mystery. Flying onboard over Po Valley in Northern Italy, Li et al. (p. 292 ) discovered undisturbed morning troposphere, indicating must be produced there, rather than mixed from surface. The high are likely to...
In contrast to summer smog, the contribution of photochemistry formation winter haze in northern mid-to-high latitude is generally assumed be minor due reduced solar UV and water vapor concentrations. Our comprehensive observations atmospheric radicals relevant parameters during several events 2016 Beijing, however, reveal surprisingly high hydroxyl radical oxidation rates up 15 ppbv/h, which comparable values reported photochemical smog two three times larger than those determined previous...
Abstract. HO2 concentration measurements are widely accomplished by chemical conversion of to OH including reaction with NO and subsequent detection laser-induced fluorescence. RO2 radicals can be converted via a similar radical sequence NO, so that they potential interferences for measurements. Here, the efficiency various species is investigated. Experiments were conducted source produces water photolysis at 185 nm, which frequently used calibration LIF instruments. The ratio sum...
Abstract. Anthropogenic emissions such as NOx and SO2 influence the biogenic secondary organic aerosol (SOA) formation, but detailed mechanisms effects are still elusive. We studied of on SOA formation from photooxidation α-pinene limonene at ambient relevant concentrations (NOx: < 1to 20 ppb, SO2: 0.05 to 15 ppb). In these experiments, monoterpene oxidation was dominated by OH oxidation. found that induced nucleation enhanced mass formation. strongly suppressed not only new particle also...
Abstract. Hydroxyl (OH) and peroxy radicals (HO2 RO2) were measured in the Pearl River Delta, which is one of most polluted areas China, autumn 2014. The radical observations complemented by measurements OH reactivity (inverse lifetime) a comprehensive set trace gases including carbon monoxide (CO), nitrogen oxides (NOx=NO, NO2) volatile organic compounds (VOCs). was range from 15 to 80 s−1, about 50 % unexplained reactants. In 3 weeks campaign, maximum median concentrations 4.5×106 cm−3 for...
Abstract Atmospheric acidity is increasingly determined by carbon dioxide and organic acids 1–3 . Among the latter, formic acid facilitates nucleation of cloud droplets 4 contributes to clouds rainwater 1,5 At present, chemistry–climate models greatly underestimate atmospheric burden acid, because key processes related its sources sinks remain poorly understood 2,6–9 Here we present chamber experiments that show formaldehyde efficiently converted gaseous via a multiphase pathway involves...
Abstract The Aerosol, Clouds and Trace Gases Research Infrastructure (ACTRIS) officially became the 33rd European Consortium (ERIC) on 25 April 2023 with support of 17 founding member observer countries. As a pan-European legal organization, ACTRIS ERIC will coordinate provision data products short-lived atmospheric constituents clouds relevant to climate air pollution over next 15–20 years. was designed more than decade ago, its development funded at national levels. It included in Strategy...
Abstract. Alkyl nitrates and secondary organic aerosol (SOA) produced during the oxidation of isoprene by nitrate radicals has been observed in SAPHIR (Simulation Atmospheric PHotochemistry In a large Reaction Chamber) chamber. A 16 h dark experiment was conducted with temperatures at 289–301 K, maximum concentrations 11 ppb isoprene, 62.4 O3 31.1 NOx. We find yield is 70±8% from + NO3 reaction, for dinitrates reaction primary 40±20%. an effective rate constant group first generation...
Abstract. We describe an instrument for simultaneous measurements of glyoxal (CHOCHO) and nitrogen dioxide (NO2) using cavity enhanced absorption spectroscopy with a broadband light source. The output Xenon arc lamp is coupled into 1 m optical cavity, the spectrum exiting recorded by grating spectrometer charge-coupled device (CCD) array detector. mirror reflectivity effective path lengths are determined from known Rayleigh scattering He dry zero air (N2+O2). Least-squares fitting, published...
This paper presents determinations of reactive uptake coefficients for N 2 O 5 , γ (N ), on aerosols from nighttime aircraft measurements ozone, nitrogen oxides, and aerosol surface area the NOAA P‐3 during Second Texas Air Quality Study (TexAQS II). Determinations based both steady state approximation NO 3 a plume modeling approach yielded ) substantially smaller than current parameterizations used atmospheric generally in range 0.5–6 × 10 −3 . Dependence variables such as relative humidity...
Air pollution is growing fastest in monsoon-affected South Asia. During the dry winter monsoon, fumes disperse toward Indian Ocean, creating a vast haze, but their fate during wet summer monsoon has been unclear. We performed atmospheric chemistry measurements by aircraft Oxidation Mechanism Observations campaign, sampling outflow upper troposphere between Mediterranean and Ocean. The measurements, supported model calculations, show that sustains remarkably efficient cleansing mechanism...
A sensitive, small detector was developed for atmospheric NO2 and NOx concentration measurements. is directly detected by laser diode based cavity ring-down spectroscopy (CRDS) at 404 nm. The sum of NO (=NOx) simultaneously measured in a second quantitative conversion ambient to excess ozone. Interferences due absorption other trace gases nm, such as ozone water vapor, are either negligible or easily quantified. limit detection 22 pptv (2σ precision) 1 s time resolution. efficiency 99% O3....
Recent studies have shown that measured OH under NO x ‐limited, high‐isoprene conditions are many times higher than modeled OH. In this study, a detailed analysis of the HO radical budgets low‐NO , rural was performed employing box model based on Master Chemical Mechanism (MCMv3.2). The results were compared with measurements during international HOxComp campaign carried out in Jülich, Germany, summer 2005. Two different air masses influenced measurement site denoted as high‐NO (NO, 1–3...