A5085426059- Atmospheric chemistry and aerosols
- Atmospheric Ozone and Climate
- Air Quality Monitoring and Forecasting
- Air Quality and Health Impacts
- Atmospheric and Environmental Gas Dynamics
- Catalytic Processes in Materials Science
- Spectroscopy and Laser Applications
- Psychology, Coaching, and Therapy
- Vehicle emissions and performance
- Odor and Emission Control Technologies
- Atmospheric aerosols and clouds
- Plant responses to elevated CO2
- Advanced Chemical Sensor Technologies
- Sociology and Education Studies
- Indoor Air Quality and Microbial Exposure
- Water Quality Monitoring and Analysis
- Coaching Methods and Impact
- Forest Insect Ecology and Management
- Insect-Plant Interactions and Control
- Ionosphere and magnetosphere dynamics
- Urban Heat Island Mitigation
- Species Distribution and Climate Change
- Industrial Gas Emission Control
- Corporate Management and Leadership
- Particle Dynamics in Fluid Flows
Forschungszentrum Jülich
2015-2024
Leibniz Institute for Tropospheric Research
2024
Institute for Food and Environmental Research
2022
Ernst Ruska Centre
2015-2022
FHNW University of Applied Sciences and Arts
2012-2020
Hirslanden Klinik Aarau
2020
Praxis
2020
Sphere Institute
2015
Stadtwerke Jülich (Germany)
2015
Institut für Soziale Arbeit
2012-2015
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...
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. 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. Emission of biogenic volatile organic compounds (VOC) which on oxidation form secondary aerosols (SOA) can couple the vegetation with atmosphere and climate. Particle formation from tree emissions was investigated in a new setup: plant chamber coupled to reaction for oxidizing forming SOA. Emissions boreal species birch, pine, spruce were studied. In addition, α-pinene used as reference compound. Under employed experimental conditions, OH radicals essential inducing particle...
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...
Abstract. Hydroxyl (OH) radical reactivity (kOH) has been measured for 18 years with different measurement techniques. In order to compare the performances of instruments deployed in field, two campaigns were conducted performing experiments atmospheric simulation chamber SAPHIR at Forschungszentrum Jülich October 2015 and April 2016. Chemical conditions chosen either be representative atmosphere or test potential limitations instruments. All types that are currently used measurements one...
Abstract. Oxidation by hydroxyl radical (OH) and ozonolysis are the two major pathways of daytime biogenic volatile organic compound (BVOC) oxidation secondary aerosol (SOA) formation. In this study, we investigated particle formation several common monoterpenes (α-pinene, β-pinene limonene) OH-dominated oxidation, which has seldom been investigated. OH experiments were carried out in SAPHIR (Simulation Atmospheric PHotochemistry a large Reaction) chamber Jülich, Germany, at low NOx (0.01 ~...
Abstract. Theoretical, laboratory, and chamber studies have shown fast regeneration of the hydroxyl radical (OH) in photochemistry isoprene, largely due to unimolecular reactions which were previously thought not be important under atmospheric conditions. Based on early field measurements, nearly complete was hypothesized for a wide range tropospheric conditions, including areas such as rainforest where slow OH radicals is expected low concentrations nitric oxide (NO). In this work isoprene...
Abstract Citizen science (CS) can foster transformative impact for science, citizen empowerment and socio-political processes. To unleash this impact, a clearer understanding of its current status challenges development is needed. Using quantitative indicators developed in collaborative stakeholder process, our study provides comprehensive overview the CS Germany, Austria Switzerland. Our online survey with 340 responses focused on through (1) scientific practices, (2) participant learning...
Abstract. NO2 concentrations were measured by various instruments during the NO3Comp campaign at atmosphere simulation chamber SAPHIR Forschungszentrum Jülich, Germany, in June 2007. Analytical methods included photolytic conversion with chemiluminescence (PC-CLD), broadband cavity ring-down spectroscopy (BBCRDS), pulsed (CRDS), incoherent cavity-enhanced absorption (IBB\\-CEAS), and laser-induced fluorescence (LIF). All spectrometers optimized for detection of main target species campaign,...
Reaction rate coefficients and product yields in the gas phase reaction of O 3 with short‐chained alkenes ethene, propene, 1‐butene, isobutene, ( E )‐butene, Z )‐butene were determined by Simulation Atmospheric Photochemistry a Large Chamber (SAPHIR). In first set experiments, acquired an absolute study from measured concentration time profiles ozone side reactions being suppressed adding radical scavenger. The obtained agree well literature data; for all but one alkene, deviation was less...
This paper presents results from the first large‐scale in situ intercomparison of oxygenated volatile organic compound (OVOC) measurements. The was conducted blind at large (270 m 3 ) simulation chamber, Simulation Atmospheric Photochemistry a Large Reaction Chamber (SAPHIR), Jülich, Germany. Fifteen analytical instruments, representing wide range techniques, were challenged with measuring atmospherically relevant OVOC species and toluene (14 species, C 1 to 7 approximate 0.5–10 ppbv under...
A chamber study was carried out to investigate the stable carbon isotopic composition ( δ 13 C) of secondary organic aerosol (SOA) formed from ozonolysis β ‐pinene. ‐Pinene (600 ppb) with a known C value (−30.1‰) and 500 ppb ozone were injected into in absence light resulting SOA collected on preheated quartz fiber filters. Furthermore, values gas‐phase ‐pinene one its oxidation products, nopinone, measured using gas chromatograph coupled an isotope ratio mass spectrometer (GC‐IRMS)....
Abstract. Ozone concentrations in the Po Valley of northern Italy often exceed international regulations. As both a source radicals and an intermediate oxidation most volatile organic compounds (VOCs), formaldehyde (HCHO) is useful tracer for oxidative processing hydrocarbons that leads to ozone production. We investigate sources HCHO using vertical profile measurements acquired from airship Zeppelin NT over agricultural region during PEGASOS 2012 campaign. Using 1-D model, total VOC rate...
Abstract. Hydroxyl radicals (OH) are the most important reagent for oxidation of trace gases in atmosphere. OH concentrations measured during recent field campaigns isoprene-rich environments were unexpectedly large. A number studies showed that unimolecular reactions organic peroxy (RO2) formed initial reaction step isoprene with play an role budget atmosphere at low mixing ratios nitrogen monoxide (NO) less than 100 pptv. It has also been suggested similar potentially RO2 from other...
The analysis of the individual composition hydrocarbon (VOC) mixtures enables us to transform observed VOC-concentrations into their respective total VOC-reactivity versus OH radicals (RVOC = Σ(kOH+VOCi × [VOCi])). This is particularly useful because local ozone production essentially depends on this single parameter rather than details underlying mixture (Klemp et al., Schriften des Forschungszentrums Jülich, Energy & Environment, 2012, 21). VOC also pin down major emission source...
Abstract. A photochemical box model constrained by ancillary observations was used to simulate OH and HO2 concentrations for three days of ambient during the HOxComp field campaign held in Jülich, Germany July 2005. Daytime levels observed four instruments were fairly well reproduced within 33% a base run (Regional Atmospheric Chemistry Mechanism with updated isoprene chemistry adapted from Master Chemical ver. 3.1) high R2 values (0.72–0.97) over range (0.3–2 ppb) NO (0.1–10 mixing ratios....
Abstract. Secondary organic aerosols (SOAs) play a key role in climate change and air quality. Determining the fundamental parameters that distribute compounds between phases is essential, as atmospheric lifetime impacts drastically gas particle phase. In this work, gas-to-particle partitioning of major biogenic oxidation products was investigated using three different aerosol chemical characterization techniques. The collection module, thermal desorption unit, analysis online are sampling...
Abstract. Besides isoprene, monoterpenes are the non-methane volatile organic compounds (VOCs) with highest global emission rates. Due to their high reactivity towards OH, can dominate radical chemistry of atmosphere in forested areas. In present study photochemical degradation mechanism β-pinene was investigated Jülich simulation chamber SAPHIR (Simulation Atmospheric PHotochemistry a large Reaction Chamber). One focus this is on OH budget process. Therefore, equipped instrumentation...
Abstract. An intercomparison of different aerosol chemical characterization techniques has been performed as part a chamber study biogenic secondary organic (BSOA) formation and aging at the atmosphere simulation SAPHIR (Simulation Atmospheric PHotochemistry In large Reaction chamber). Three sampling – collection module (ACM), analysis online (CHARON) thermal-desorption unit (TD) were connected to proton transfer reaction time-of-flight mass spectrometers (PTR-ToF-MSs) provide SOA. The...
Abstract. The performance of 18 European institutions involved in long-term non-methane hydrocarbon (NMHC) measurements ambient air within the framework Global Atmosphere Watch (GAW) and Monitoring Evaluation Programme (EMEP) was assessed with respect to data quality objectives (DQOs) ACTRIS (Aerosols, Clouds, Trace gases Research InfraStructure Network) GAW. Compared previous intercomparison studies DQOs define a novel approach assess ensure high measurements. Having already been adopted by...
Abstract. Several previous field studies have reported unexpectedly large concentrations of hydroxyl and hydroperoxyl radicals (OH HO2, respectively) in forested environments that could not be explained by the traditional oxidation mechanisms largely underestimated observations. These were characterized biogenic volatile organic compounds (BVOC) low nitrogen oxide concentration. In isoprene-dominated environments, models developed to simulate atmospheric photochemistry generally observed OH...