A5027152520- Atmospheric aerosols and clouds
- Atmospheric chemistry and aerosols
- Icing and De-icing Technologies
- Spectroscopy and Laser Applications
- Meteorological Phenomena and Simulations
- Atmospheric Ozone and Climate
- Laser Design and Applications
- Freezing and Crystallization Processes
- Aeolian processes and effects
- Wind and Air Flow Studies
- Atmospheric and Environmental Gas Dynamics
- Precipitation Measurement and Analysis
- nanoparticles nucleation surface interactions
- Plant Surface Properties and Treatments
- Aerosol Filtration and Electrostatic Precipitation
- Advanced Chemical Sensor Technologies
- Fluid Dynamics and Heat Transfer
- Fermentation and Sensory Analysis
- Gas Sensing Nanomaterials and Sensors
- Aerodynamics and Fluid Dynamics Research
- Surface Modification and Superhydrophobicity
- Smart Materials for Construction
- Aerospace Engineering and Energy Systems
- Magnetic and Electromagnetic Effects
- Spaceflight effects on biology
Johannes Gutenberg University Mainz
2013-2024
NSF National Center for Atmospheric Research
2020
Insurance Institute for Highway Safety
2020
Environment and Climate Change Canada
2020
University of Szeged
1999-2020
Max Planck Society
2007-2008
Max Planck Institute for Chemistry
2007-2008
Hungarian Academy of Sciences
2003-2006
Abstract. The second phase of the Fifth International Ice Nucleation Workshop (FIN-02) involved gathering a large number researchers at Karlsruhe Institute Technology's Aerosol Interactions and Dynamics Atmosphere (AIDA) facility to promote characterization understanding ice nucleation measurements made by variety methods used worldwide. Compared previous workshop in 2007, participation was doubled, reflecting vibrant research area. Experimental sampling aerosol particles direct processing...
Abstract. We present the laboratory results of immersion freezing efficiencies cellulose particles at supercooled temperature (T) conditions. Three types chemically homogeneous samples are used as surrogates that represent supermicron and submicron ice-nucleating plant structural polymers. These include microcrystalline (MCC), fibrous (FC) nanocrystalline (NCC). Our dataset includes data from various ice nucleation measurement techniques available 17 different institutions, including nine...
Abstract This study uses novel approaches to estimate the fall characteristics of hail, covering a size range from about 0.5 7 cm, and drag coefficients lump conical graupel. Three-dimensional (3D) volume scans 60 hailstones sizes 2.5 6.7 cm were printed in three dimensions using acrylonitrile butadiene styrene (ABS) plastic, their terminal velocities measured Mainz, Germany, vertical wind tunnel. To simulate graupel, 40 with maximum 0.2, 0.3, measured. Conical whose (maximum dimension 0.1–1...
Abstract Precipitation prediction using weather radars requires detailed knowledge of the shape parameters raindrops falling at their terminal velocities in air. Because undergo oscillation, most important from radar point view are equilibrium drop shape, time-averaged axis ratio, and oscillation frequency. These for individual water drops with equivalent diameter 2.5 to 7.5 mm were investigated a vertical wind tunnel high-speed video imaging. A very good agreement was found between measured...
Abstract. Particle concentration measurements with underwing probes on aircraft are impacted by air compression upstream of the instrument body as a function flight velocity. In particular, for fast-flying necessity arises to account sample volume. Hence, correction procedure is needed invert measured particle number concentrations ambient conditions that commonly applicable different instruments gain comparable results. region where detection particles occurs (i.e. under factual measurement...
Understanding the interaction between freezing processes and vertical movement of trace gases into upper atmosphere during intense convection is essential for analyzing distribution aerosol precursors their impact on climate. We conducted experimental studies in a cold room with freely suspended raindrops (2 mm diameter) using an acoustic levitation setup. For first time, we examined how affects retention organic species, silver iodide as ice nucleating agent. Through quantitative chemical...
Abstract. Carbonyls are highly relevant atmospheric constituents that influence tropospheric photochemistry and oxidative capacity. They can be removed from the upper troposphere via ice phase deposition scavenging. The gas-ice partitioning coefficients for 14 different carbonyl compounds were determined using a flowtube apparatus. Ice crystals grown vapor in presence of gas carbonyls at –20, –30, –40 °C. Using van’t Hoff analysis, entropy enthalpy uptake determined. An inverse relationship...
Abstract Comparisons of drop shapes between measurements made using 2D video disdrometer (2DVD) and wind-tunnel experiments are presented. in terms the mean axis ratio distributions. Very close agreement is seen two sets measurements; same applies to versus diameter. Also, both measurements, an increase oscillation amplitudes with increasing diameter observed. In case 2DVD, a small skewness was also detected. Given that were conducted very different conditions, data implies certain...
Abstract. During free fall in clouds, ice hydrometeors such as snowflakes and particles grow effectively by riming, i.e., the accretion of supercooled droplets. Volatile atmospheric trace constituents dissolved droplets may remain during freezing or be released back to gas phase. This process is quantified retention coefficients. Once phase vertically redistributed scavenging subsequent precipitation evaporation these at high altitudes. Retention coefficients most dominant carboxylic acids...
Abstract. This study reports the first systematic measurements of nitric acid (HNO3) uptake in contrail ice particles at typical aircraft cruise altitudes. During CIRRUS-III campaign cirrus clouds and almost 40 persistent contrails were probed with situ instruments over Germany Northern Europe November 2006. Besides reactive nitrogen, water vapor, cloud content, particle size distributions, condensation nuclei measured during 6 flights. Contrails ages up to 12 h detected altitudes 10–11.5 km...
Abstract Vertical wind tunnel experiments were carried out to investigate the melting of low-density lump graupel while floating at their terminal velocities. The characteristics such as maximum dimension, density, and axis ratio 0.39 ± 0.06 cm, 0.41 0.07 g cm −3 , 0.89 0.06. airstream was gradually heated simulating lapse rates between 4.5 3.21 K km −1 . Each experimental run performed a constant relative humidity that varied 12% 92% from one experiment other. From image processing video...
Although water vapor is one of the most important and certainly variable minor constituent atmosphere, accurate measurements p(H2O) with high time resolution are difficult, particularly in cold upper troposphere/lower stratosphere. This work demonstrates that a diode laser-based photoacoustic (PA) detector viable alternative to current sensors for airborne measurements. The PA system was compared high-quality frost point hygrometer (FPH) Lyman-α pressure range 1000−100 hPa at temperatures...
A wavelength modulated, distributed feedback diode laser based photoacoustic water vapor mixing ratio measuring system for atmospheric research applications is presented. Laser modulation parameters were optimized either at 180 or 500 mbar total pressure to enhance the system's sensitivity low high pressures (upper troposphere/lower stratosphere biosphere exchange layer), respectively. locking method was developed that ensured sub-picometer absolute (5 x 10(-7) relative) stability of while...
Photoacoustic spectroscopy, based on an external cavity diode laser operating at 1431 nm, was used for measuring CO 2 concentration as a minority component in gas mixture. By using N buffer gas, molecular relaxation effect observed, which influenced both the amplitude and phase of measured photoacoustic signal consequently reduced sensitivity PA system. This could be suppressed by adding water vapor constant relatively high (∼4%) to sample. In parallel with this, arising spectral...