Ottmar Möhler
A5089697844- Atmospheric chemistry and aerosols
- Atmospheric aerosols and clouds
- Atmospheric Ozone and Climate
- Icing and De-icing Technologies
- Air Quality and Health Impacts
- nanoparticles nucleation surface interactions
- Aeolian processes and effects
- Arctic and Antarctic ice dynamics
- Atmospheric and Environmental Gas Dynamics
- Air Quality Monitoring and Forecasting
- Smart Materials for Construction
- Cryospheric studies and observations
- Meteorological Phenomena and Simulations
- Catalytic Processes in Materials Science
- Freezing and Crystallization Processes
- Plant responses to elevated CO2
- Vehicle emissions and performance
- Industrial Gas Emission Control
- Ionosphere and magnetosphere dynamics
- Indoor Air Quality and Microbial Exposure
- Thermal Radiation and Cooling Technologies
- Advanced Aircraft Design and Technologies
- Particle Dynamics in Fluid Flows
- Geophysics and Gravity Measurements
- Spectroscopy and Laser Applications
Karlsruhe Institute of Technology
2016-2025
Physikalisch-Technische Bundesanstalt
2019
Cooperative Institute for Research in Environmental Sciences
2019
University of Chicago
2019
Laboratoire de Météorologie Physique
2018
Swiss Federal Institute of Aquatic Science and Technology
2018
Centre National de la Recherche Scientifique
2018
Nagoya University
2018
Max Planck Institute for Meteorology
2018
Paul Scherrer Institute
2018
Abstract About half of present-day cloud condensation nuclei originate from atmospheric nucleation, frequently appearing as a burst new particles near midday 1 . Atmospheric observations show that the growth rate often accelerates when diameter is between one and ten nanometres 2,3 In this critical size range, are most likely to be lost by coagulation with pre-existing 4 , thereby failing form typically 50 100 across. Sulfuric acid vapour involved in nucleation but too scarce explain...
Abstract In climate and weather models, the quantitative description of aerosol cloud processes relies on simplified assumptions. This contributes major uncertainties to prediction global regional change. Therefore, models need good parameterizations for heterogeneous ice nucleation by atmospheric aerosols. Here authors present a new parameterization immersion freezing desert dust particles derived from large number experiments carried out at Aerosol Interaction Dynamics in Atmosphere (AIDA)...
Abstract. Terminology dealing with ice nucleation in the atmosphere, biological systems, and other areas has not kept pace growth of empirical evidence development new ideas over recent decades. Ambiguities misinterpretations could be seen literature. This paper offers a set definitions for various terms common use, adds some qualifications, introduces ones. Input been received on interpretation from fair number researchers; diverse views have accommodated success. It is anticipated that...
Abstract. Data from both laboratory studies and atmospheric measurements are used to develop an empirical parameterization for the immersion freezing activity of natural mineral dust particles. Measurements made with Colorado State University (CSU) continuous flow diffusion chamber (CFDC) when processing aerosols at a nominal 105% relative humidity respect water (RHw) taken as measure nucleation Ice active frozen fractions vs. temperature dusts representative Saharan Asian desert sources...
The scattering and absorption properties of black carbon (BC) particles internally mixed with secondary organic aerosol (SOA) were investigated experimentally at the large chamber facility AIDA. Diesel soot coated compounds produced by in situ ozonolysis α‐pinene. It was found that coating strongly affects optical microphysical aggregates. Amplification factors BC 1.8 to 2.1 compared specific cross section externally measured. These amplification are well reproduced a Mie model for...
Abstract. As part of a series papers on the sources, distribution and potential impact biological particles in atmosphere, this paper introduces summarizes role atmospheric clouds. Biological like bacteria or pollen may be active as both cloud condensation nuclei (CCN) heterogeneous ice (IN) thereby can contribute to initial formation stages development precipitation through giant CCN IN processes. The gives an introduction aerosol-cloud processes involving general provides short summary...
Abstract. The deposition mode ice nucleation efficiency of various dust aerosols was investigated at cirrus cloud temperatures between 196 and 223 K using the aerosol chamber facility AIDA (Aerosol Interaction Dynamics in Atmosphere). Arizona test (ATD) as a reference material two samples from Takla Makan desert Asia (AD1) Sahara (SD2) were used for experiments simulated conditions. particle sizes almost lognormally distributed with diameters 0.3 0.5 μm geometric standard deviations 1.6 1.9....
Abstract Based on results of 11 yr heterogeneous ice nucleation experiments at the Aerosol Interaction and Dynamics in Atmosphere (AIDA) chamber Karlsruhe, Germany, a new empirical parameterization framework for was developed. The currently includes desert dust soot aerosol quantifies efficiency terms active surface site (INAS) approach. immersion freezing INAS densities nS all follow an exponential fit as function temperature, well agreement with earlier analysis AIDA experiments....
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. We present results of experiments at the aerosol interactions and dynamics in atmosphere (AIDA) chamber facility looking freezing water by three different types mineral particles temperatures between −12°C −33°C. The dusts are Asia Dust-1 (AD1), Sahara Dust-2 (SD2) Arizona test Dust (ATD). dust samples used had particle concentrations sizes that were log-normally distributed with mode diameters 0.3 0.5 μm standard deviations, σg, 1.6–1.9. from consistent singular hypothesis ice...
The effect of organic coating on the heterogeneous ice nucleation (IN) efficiency dust particles was investigated at simulated cirrus cloud conditions in AIDA chamber Forschungszentrum Karlsruhe. Arizona test (ATD) and clay mineral illite were used as surrogates for atmospheric aerosols. dry samples dispersed into a 3.7 m3 aerosol vessel either directly transferred 84 simulation or coated before with semi-volatile products from reaction α-pinene ozone order to mimic secondary (SOA)...
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. We present a new mobile environmental reaction chamber for the simulation of atmospheric aging different emission sources without limitation from instruments or facilities available at any single site. Photochemistry is simulated using set 40 UV lights (total power 4 KW). Characterisation spectrum these shows that emissions may be over range temperatures (−7 to 25 °C). A photolysis rate NO2, JNO2, (8.0 ± 0.7) × 10−3 s−1 was determined °C. demonstrate utility this system by...
Understanding cloud and precipitation responses to variations in atmospheric aerosols remains an important research topic for improving the prediction of climate. Knowledge is most uncertain, potential impact on climate largest with regard how ice formation clouds. In this paper, we show that nucleation, including development new measurement systems, occurring at a renewed historically unparalleled level. A historical perspective provided methods challenges measuring nuclei, various factors...
Faster than expected Iodine species are one of only a handful atmospheric vapors known to make new aerosol particles, which play central role in controlling the radiative forcing climate. He et al. report experimental evidence from CERN Cosmics Leaving Outdoor Droplets, or CLOUD, chamber demonstrating that iodic acid and iodous rapidly form particles can compete with sulfuric pristine regions. Science , this issue p. 589
Abstract. Dust particles from high latitudes have a potentially large local, regional, and global significance to climate the environment as short-lived forcers, air pollutants, nutrient sources. Identifying locations of local dust sources their emission, transport, deposition processes is important for understanding multiple impacts high-latitude (HLD) on Earth's systems. Here, we identify, describe, quantify source intensity (SI) values, which show potential soil surfaces emission scaled...
The mechanistic pathway by which high relative humidity (RH) affects gas–particle partitioning remains poorly understood, although many studies report increased secondary organic aerosol (SOA) yields at RH. Here, we use real-time, molecular measurements of both the gas and particle phase to provide a understanding effect RH on biogenic oxidized molecules (from α-pinene isoprene) low temperatures (243 263 K) CLOUD chamber CERN. We observe increases in SOA mass 45 85% with increasing from...
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...
Laboratory measurements support a cirrus cloud formation pathway involving heterogeneous ice nucleation by solid ammonium sulfate aerosols. Ice occurs at low ice-saturation ratios consistent with the of continental and an interhemispheric asymmetry observed for onset. In climate model, this mechanism provides widespread source nuclei leads to fewer but larger crystals as compared homogeneous freezing scenario. This reduces both albedo longwave heating cirrus. With global ammonia budget...
The low‐temperature aerosol and cloud chamber AIDA (Aerosol Interactions Dynamics in the Atmosphere) of Forschungszentrum Karlsruhe was used to investigate effect sulfuric acid coating on ice nucleation efficiency soot particles from a spark discharge generator. uncoated (sulfuric acid–coated) showed nearly lognormal size distribution with number concentrations 300–5000 cm −3 (2500–56,000 ), count median diameters 70–140 nm (90–200 nm), geometric standard deviation 1.3–1.4 (1.5–1.6). volume...
Abstract. Secondary organic aerosol (SOA) formation has been investigated as a function of temperature and humidity for the ozone-initiated reaction two monoterpenes α-pinene (243–313 K) limonene (253–313 using 84.5 m3 chamber AIDA. This paper gives an overview measurements done presents parameters specifically useful yield calculations. The ozonolysis reaction, selected oxidation products subsequent were followed several analytical techniques both gas condensed phase characterisation....