A5055665516- Atmospheric aerosols and clouds
- Atmospheric chemistry and aerosols
- Icing and De-icing Technologies
- Atmospheric Ozone and Climate
- nanoparticles nucleation surface interactions
- Freezing and Crystallization Processes
- Arctic and Antarctic ice dynamics
- Aeolian processes and effects
- Air Quality and Health Impacts
- Spectroscopy and Quantum Chemical Studies
- Fire effects on ecosystems
- Cryospheric studies and observations
- Magnetic and Electromagnetic Effects
- Particle Dynamics in Fluid Flows
- Microfluidic and Bio-sensing Technologies
- Combustion and Detonation Processes
- Surface Modification and Superhydrophobicity
- Catalytic Processes in Materials Science
- Crystallization and Solubility Studies
- Methane Hydrates and Related Phenomena
- Coagulation and Flocculation Studies
- Winter Sports Injuries and Performance
- Climate change and permafrost
- Vehicle emissions and performance
- Industrial Gas Emission Control
Karlsruhe Institute of Technology
2016-2025
National Institute of Meteorology
2011-2025
Experimental Station
2020
National Observatory of Athens
2017
Foundation for Research and Technology Hellas
2017
Georgia Institute of Technology
2017
Heidelberg University
2016
Leibniz Institute for Tropospheric Research
2004-2013
Leipzig University
2006
Czech Academy of Sciences, Institute of Physics
1996
From dust to ice How does form on the surfaces of aerosol particles? The process is important for climate and atmospheric properties but poorly understood at molecular level, in part because nature sites where growth begins unclear. Kiselev et al. used electron microscopy computer simulations study deposition aligned crystals feldspar, a major component mineral (see Perspective by Murray). Surface defects feldspar were responsible its high ice-nucleation efficiency. Science , this issue p....
Abstract. Immersion freezing is the most relevant heterogeneous ice nucleation mechanism through which crystals are formed in mixed-phase clouds. In recent years, an increasing number of laboratory experiments utilizing a variety instruments have examined immersion activity atmospherically ice-nucleating particles. However, intercomparison these results difficult task because investigators used different (IN) measurement methods to produce results. A remaining challenge explore sensitivity...
Abstract. A recently designed droplet freezing assay was used to study the of up 1500 identical 0.2 nL water droplets containing suspensions one Na/Ca-rich feldspar and three K-rich particles. Three types experiments have been conducted: cooling ramp, isothermal at a constant temperature, freeze–thaw cycles. The observed behavior has interpreted with help model based on classical nucleation theory (soccer ball (SBM); Niedermeier et al., 2015). By applying different conducted same...
Abstract The formation of secondary ice in clouds, that is, particles are created at temperatures above the limit for homogeneous freezing without direct involvement a heterogeneous nucleus, is one longest-standing puzzles cloud physics. Here, we present comprehensive laboratory investigations on small upon drizzle-sized droplets levitated an electrodynamic balance. Four different categories (bubble bursting, jetting, cracking, and breakup) could be detected, their respective frequencies...
Abstract. Seven different instruments and measurement methods were used to examine the immersion freezing of bacterial ice nuclei from Snomax® (hereafter Snomax), a product containing ice-active protein complexes non-viable Pseudomonas syringae bacteria. The experimental conditions kept as similar possible for measurements. Of participating instruments, some examined droplets which had been made suspensions directly, others activated on previously generated Snomax particles, with particle...
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. During the measurement campaign FROST (FReezing Of duST), LACIS (Leipzig Aerosol Cloud Interaction Simulator) was used to investigate immersion freezing behavior of size selected, coated and uncoated Arizona Test Dust (ATD) particles with a mobility diameter 300 nm. Particles were succinic acid (C4H6O4), sulfuric (H2SO4) ammonium sulfate ((NH4)2SO4). Ice fractions at mixed-phase cloud temperatures ranging from 233.15 K 239.15 (±0.60 K) determined for all types particles. In this...
The LACIS Experiment in November (LExNo) campaign was conducted 2005 at the Atmospheric Composition Change European Network of Excellence (ACCENT) site Leipzig Aerosol Cloud Interaction Simulator (LACIS). goal LExNo to provide deeper insight into activation properties coated soot particles imitating aged combustion aerosol particles. aerosols were prepared by starting with spark‐generated In some experiments compacted exposure propanol vapor; others this step bypassed. thermally ammonium...
Abstract. Disparities between the measured concentrations of ice-nucleating particles (INPs) and in-cloud ice crystal number (ICNCs) have led to hypothesis that mechanisms other than primary nucleation form in atmosphere. Here, we model three these secondary production – rime splintering, frozen droplet shattering, ice–ice collisional breakup with a six-hydrometeor-class parcel model. We perform sets simulations understand temporal evolution hydrometeor (Nice), thermodynamic limitations,...
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 Ice multiplication processes are known to be responsible for the higher concentration of ice particles versus nucleating in clouds, but exact secondary formation mechanisms remain quantified. Recent in-cloud observations and modeling studies have suggested importance production upon shattering freezing drizzle droplets. In one our previous studies, four categories during supercooled droplets been identified: breakup, cracking, jetting, bubble bursts. this work, we extend study...
Abstract. In recent years, sea spray as well the biological material it contains has received increased attention a source of ice-nucleating particles (INPs). Such INPs may play role in remote marine regions, where other sources are scarce or absent. Arctic, these can influence water–ice partitioning low-level clouds and thereby cloud lifetime, with consequences for surface energy budget, ice formation melt, climate. Marine aerosol is diverse nature, so identifying challenging. One fraction...
An atmospheric HULIS (humic‐like substance) sample dissolved in water was used to generate particles with different dry diameters. A HHTDMA (High Humidity Tandem Differential Mobility Analyzer) and LACIS (Leipzig Aerosol Cloud Interaction Simulator) were measure hygroscopic growth of the particles. also critical super‐saturation for activation diameters 50, 75, 100, 125 nm. Simple Köhler theory simulate measured factors. For this, a new technique used, where ionic density ( ρ ion ) defined...
Abstract. In this paper, the effect of morphological modification aerosol particles with respect to heterogeneous ice nucleation is comprehensively investigated for laboratory-generated hematite as a model substrate atmospheric dust particles. The surface-area-scaled efficiencies monodisperse cubic and milled were measured series expansion cooling experiments using Aerosol Interaction Dynamics in Atmosphere (AIDA) cloud simulation chamber. Complementary offline characterization...
Abstract. The hygroscopic growth and droplet activation of uncoated soot particles such coated with succinic acid sulfuric were investigated during the IN-11 campaign at Aerosol Interaction Dynamics in Atmosphere (AIDA) facility. A GFG-1000 generator applying either nitrogen or argon as carrier gas a miniCAST utilized to generate particles. Different organic carbon (OC) black (BC) ratios adjusted for CAST-soot by varying fuel air ratio. was means mobile Leipzig Cloud Simulator (LACIS-mobile)...
Abstract. Under certain conditions, secondary organic aerosol (SOA) particles can exist in the atmosphere an amorphous solid or semi-solid state. To determine their relevance to processes such as ice nucleation chemistry occurring within requires knowledge of temperature and relative humidity (RH) range for SOA these states. In Cosmics Leaving Outdoor Droplets (CLOUD) experiment at The European Organisation Nuclear Research (CERN), we deployed a new situ optical method detect viscous state...
In this paper, a new device is introduced to study the formation and growth of cloud droplets under near-atmospheric supersaturations. The device, called Leipzig Aerosol Cloud Interaction Simulator (LACIS), based on laminar flow tube. It has been designed reproduce thermodynamic conditions atmospheric clouds as realistically possible. A series experiments have conducted that prove definition stability field inside LACIS well reproducibility generated droplet size distributions function...
Abstract. The Leipzig Aerosol Cloud Interaction Simulator (LACIS) was used to investigate the hygroscopic growth and activation of sea-salt particles which were generated from three different sea-water samples. measurements showed that exhibit a slightly reduced compared pure NaCl particles. Köhler theory utilized model these Some parameters in this are unknown for sea-salt. These combined an "ionic density" ρion. For each sample average ρion determined by fitting equation data measurements....
Abstract. At the Leipzig Aerosol Cloud Interaction Simulator (LACIS) experiments investigating homogeneous and heterogeneous nucleation of ice (particularly immersion freezing in latter case) have been carried out. Here both physical LACIS setup numerical model developed to design at interpret their results are presented detail. Combining from with experimental data, it was found that for parameter space considered, classical theory is able predict behavior highly diluted ammonium sulfate...
Abstract. During the measurement campaign FROST 2 (FReezing Of duST 2), Leipzig Aerosol Cloud Interaction Simulator (LACIS) was used to investigate influence of various surface modifications on ice nucleating ability Arizona Test Dust (ATD) particles in immersion freezing mode. The dust were exposed sulfuric acid vapor, water vapor with and without addition ammonia gas, heat using a thermodenuder operating at 250 °C. Size selected, quasi monodisperse mobility diameter 300 nm fed into LACIS...
Abstract. During the eruption of Eyjafjallajökull volcano in south Iceland April/May 2010, about 40 Tg ash mass were emitted into atmosphere. It was unclear whether volcanic particles with d < 10 μm facilitate glaciation clouds. Thus, ice nucleation properties investigated AIDA (Aerosol Interaction and Dynamics Atmosphere) cloud chamber experiments simulating atmospherically relevant conditions. The sample that used for our had been collected at a distance 58 km from during period April...
Abstract. Surface charge is one of the surface properties atmospheric aerosols, which has been linked to heterogeneous ice nucleation and hence cloud formation, microphysics, optical properties. Despite importance for nucleation, many questions remain on molecular-level mechanisms at work. Here, we combine droplet-freezing assay studies with vibrational sum frequency generation (SFG) spectroscopy correlate interfacial water structure strength. We study immersion freezing aqueous solutions...
Abstract The ice nucleation ability of α ‐pinene secondary organic aerosol (SOA) particles was investigated at temperatures between 253 and 205 K in the Aerosol Interaction Dynamics Atmosphere cloud simulation chamber. Pristine SOA were nucleated grown from pure gas precursors then subjected to repeated expansion cooling cycles compare their intrinsic during first event with that observed after processing. unprocessed found be inefficient ice‐nucleating cirrus temperatures, onsets (for an...
Abstract. Ice-nucleating particles (INPs), which are precursors for ice formation in clouds, can alter the microphysical and optical properties of thereby impacting cloud lifetimes hydrological cycles. However, mechanisms with these INPs nucleate when exposed to different atmospheric conditions still unclear some particles. Recently, pores or permanent surface defects regular irregular geometries have been reported initiate at cirrus temperatures via liquid phase a two-step process,...