A5089298943- Atmospheric chemistry and aerosols
- Atmospheric aerosols and clouds
- Air Quality and Health Impacts
- Atmospheric Ozone and Climate
- Aeolian processes and effects
- Meteorological Phenomena and Simulations
- Atmospheric and Environmental Gas Dynamics
- Icing and De-icing Technologies
- Air Quality Monitoring and Forecasting
- nanoparticles nucleation surface interactions
- Arctic and Antarctic ice dynamics
- Particle Dynamics in Fluid Flows
- Electrohydrodynamics and Fluid Dynamics
- Carbon Dioxide Capture Technologies
- Spectroscopy and Quantum Chemical Studies
- Cryospheric studies and observations
- Chemical and Physical Properties in Aqueous Solutions
- Plant Surface Properties and Treatments
- Vehicle emissions and performance
- Advanced Aircraft Design and Technologies
- Connective Tissue Growth Factor Research
- Fire effects on ecosystems
- Oil, Gas, and Environmental Issues
- Climate variability and models
- Industrial Gas Emission Control
Finnish Meteorological Institute
2015-2025
Georgia Institute of Technology
2011-2014
University of Eastern Finland
2004-2009
University of Helsinki
2008
Framework for Change Organic aerosols make up 20 to 90% of the particulate mass troposphere and are important factors in both climate human heath. However, their sources removal pathways very uncertain, atmospheric evolution is poorly characterized. Jimenez et al. (p. 1525 ; see Perspective by Andreae ) present an integrated framework organic aerosol compositional atmosphere, based on model results field laboratory data that simulate dynamic aging behavior aerosols. Particles become more...
Abstract. Atmospheric aerosol particles typically consist of inorganic salts and organic material. The compounds as well their hygroscopic properties are defined, but the effect on cloud droplet activation is still poorly characterized. focus present study that surface active i.e. tend to concentrate decrease tension. Gibbsian thermodynamics was used find out how partitioning between bulk affects tension surfactant concentration in droplets large enough act condensation nuclei. Sodium...
Cloud droplets form by nucleation on atmospheric aerosol particles. Populations of such particles invariably contain organic material, a major source which is thought to be condensation photo‐oxidation products biogenic volatile compounds (VOCs). We demonstrate that smog chamber studies the formation secondary (SOA) formed during must conducted at near concentrations yield atmospherically representative particle composition, hygroscopicity and cloud‐forming potential. Under these conditions,...
Abstract. Organic compounds with surfactant properties are commonly found in atmospheric aerosol particles. Surface activity can significantly influence the cloud droplet forming ability of these We have studied formation by two-component particles comprising one organic surfactants sodium octanoate, decanoate, dodecanoate, and dodecyl sulfate, mixed chloride. Critical supersaturations were measured a static diffusion condensation nucleus counter (Wyoming CCNC-100B). Results modeled from...
Abstract. Measurements of size-resolved cloud condensation nuclei (CCN) concentrations, subsaturated hygroscopic growth, size distribution, and chemical composition were collected from March through May, 2007, in the remote Boreal forests Hyytiälä, Finland, as part European Integrated project on Aerosol Cloud Climate Air Quality Interactions (EUCAARI) campaign. Hygroscopicity parameter, κ, distributions derived independently Continuous Flow-Streamwise Thermal Gradient CCN Chamber (CFSTGC)...
Abstract. Organosulfates have been observed as constituents of atmospheric aerosols in a wide range environments; however their hygroscopic properties remain uncharacterised. Here, limonene-derived organosulfates with molecular weight 250 Da (L-OS 250) were synthesised and used for simultaneous measurements hygroscopicity tandem differential mobility analyser (H-TDMA) cloud condensation nuclei counter (CCNC) to determine the parameter, κ, pure L-OS mixtures ammonium sulfate (AS) over...
Abstract. We perform a model intercomparison of summertime high Arctic (> 80∘ N) clouds observed during the 2008 Summer Cloud Ocean Study (ASCOS) campaign, when cloud condensation nuclei (CCN) concentrations fell below 1 cm−3. Previous analyses have suggested that at these low CCN liquid water content (LWC) and radiative properties are determined primarily by concentrations, conditions previously been referred to as tenuous regime. The includes results from three large eddy simulation...
We have measured critical supersaturations of dried single-component particles sodium caprylate [CH3(CH2)6COONa], caprate [CH3(CH2)8COONa], laurate [CH3(CH2)10COONa] and myristate [CH3(CH2)12COONa] in the diameter range 33–140 nm at 296 K using a static thermal gradient diffusion cloud condensation nucleus counter. These fatty acid salts are surface active molecules which all been identified atmospheric aerosol particles. Experimental increased systematically with increasing carbon chain...
Abstract. An Aerodyne quadrupole aerosol mass spectrometer (Q-AMS) was deployed in Hyytiälä, a forested rural measurement site southern Finland, during 2-week campaign spring 2005. Q-AMS measures concentrations of non-refractory species including sulphate, nitrate, ammonium and organics from submicron particles. A positive matrix factorization method used identifying two oxygenated organic (OOA) groups the measured total mass. The properties these were estimated their diurnal concentration...
Abstract. Observations of aerosol hygroscopic growth and CCN activation spectra for submicron particles are reported the T1 ground site outside Mexico City during MIRAGE 2006 campaign. κ-Köhler theory is used to evaluate characteristic hygroscopicity parameter, κ*, active population using both size-resolved HTMDA CCNc measurements. Organic mass fractions (forg) evaluated from spectrometer (AMS) measurements, which predictions parameter compared against κ*. Strong diurnal changes in water...
Abstract. The study investigates the sources of fine organic aerosol (OA) in boreal forest, based on measurements including both filter sampling (PM1) and online methods carried out during a one-month campaign held Hyytiälä, Finland, spring 2007. Two mass spectrometers (Q-AMS, ToF-AMS) were employed to measure on-line concentrations major non-refractory species, while water extracts samples analyzed by nuclear magnetic resonance (NMR) spectroscopy for functional group characterization polar...
Abstract. Challenges in understanding the aerosol–cloud interactions and their impacts on global climate highlight need for improved knowledge of underlying physical processes feedbacks as well with cloud boundary layer dynamics. To pursue this goal, increasingly sophisticated cloud-scale models are needed to complement limited supply observations between aerosols clouds. For purpose, a new large-eddy simulation (LES) model, coupled an interactive sectional description clouds, is introduced....
Abstract. A fraction of the Himalayan aerosols originate from secondary sources, which are currently poorly quantified. To clarify climatic importance regional particle formation in Himalayas, data 2005 to 2010 continuous aerosol measurements at a high-altitude (2180 m) Indian site, Mukteshwar, were analyzed. For this period, days classified, and growth rates calculated for clear new (NPF) event days. The NPF events showed pronounced seasonal cycle. frequency peaked spring, when ratio...
Abstract. Atmospheric aerosol composition was measured using a Single Particle Soot Photometer (SP2) in the Finnish Arctic during winter 2011–2012. The Sammaltunturi measurement site at Pallas GAW (Global Atmosphere Watch) station receives air masses from different source regions including Ocean and continental Europe. SP2 provides detailed information about mass distributions mixing state of refractory black carbon (rBC). measurements showed widely varying rBC concentrations (0–120 ng m−3),...
Abstract. We have measured black carbon properties by using a size-selected single-particle soot photometer (SP2). The measurements were conducted in northern India at two sites: Gual Pahari is located the Indo-Gangetic Plain (IGP) and Mukteshwar Himalayan foothills. Northern known as one of absorbing aerosol hot spots, but detailed information about mixing state still largely missing. Previous equivalent (eBC) mass concentration are available for this region, these consistent with our...
Abstract. In this work, existing and modified activity coefficient models are examined in order to assess their capabilities describe the properties of aqueous solution droplets relevant atmosphere. Five different water-organic-electrolyte were first selected from literature. Only one these included organics electrolytes which common atmospheric aerosol particles. other models, organic species solvents such as alcohols, important ions like NH4+ could be missing. The predictions compared...
Abstract. Aerosol physical and optical properties were measured at two locations in northern India. The first measurement station was a background site Mukteshwar, about 350 km northeast of New Delhi, the foothills Indian Himalayas, with data from 2006 to 2009. second located Gual Pahari, 25 south 2008 At both stations, average aerosol concentrations during monsoon decreased by 40–75 % compared pre-monsoon concentrations. decrease varied total local rainfall. In season removed particles all...
Humic like substances (HULIS) are a class of compounds that suspected to have an effect on cloud droplet activation properties atmospheric aerosols because they decrease the surface tension aqueous solutions quite efficiently. Surface active organic tendency concentrating surfaces liquid droplets. If total amount compound is small enough, partitioning substance depletes it from interior, decreasing Raoult and increasing Kelvin effect. Thus, causes increase critical supersaturation (Köhler...
Abstract. Surface tension of ternary solution sodium chloride, succinic acid and water was measured as a function both composition temperature by using the capillary rise technique. Both chloride are found in atmospheric aerosols, former being main constituent marine aerosol. Succinic to decrease surface already at very low concentrations. Sodium increased linearly concentration. tensions binary solutions agreed well with previous measurements. lower even if is present, indicating that acid,...
Cloud droplet formation depends on the condensation of water vapor ambient aerosols, rate which is strongly affected by kinetics uptake as expressed (or mass accommodation) coefficient, α c . Estimates for growth from activation particles vary considerably and represent a critical source uncertainty in estimates global cloud distributions aerosol indirect forcing climate. We present an analysis 10 globally relevant data sets nuclei to constrain value aerosol. find that rapid (α > 0.1)...
Abstract. Artificial enhancement of precipitation via hygroscopic cloud seeding is investigated with a numerical large-eddy simulation model coupled spectral aerosol–cloud microphysics module. We focus our investigation on marine stratocumulus clouds and evaluate results by comparing them recently published from field observations. Creating multiple realizations single event the provides robust method to detect attribute effects, which reinforces analysis based experimental data. Owing...
Secondary ice production (SIP) refers to a series of physical mechanisms that significantly increase number concentrations above those from primary (PIP) via nucleating particles (INP). In-cloud observations have provided increasing evidence SIP in mixed-phase stratiform and convective clouds at different latitudes. The presence fragmented frozen drops small columnar measurements holographic particle imaging systems is consistent with findings laboratory experiments focused on rime...
Abstract. Particulate matter (PM) and equivalent black carbon (BCe) concentrations were measured at two locations in northern India during 2006–2010. The first measurement station was a background site Mukteshwar, about 350 km northeast of New Delhi, the foothills Indian Himalayas. second located Gual Pahari, 25 south Delhi. Here we focused on resolving effects summer monsoon particulate stations. average time decreased by 55–70 % compared to pre-monsoon both stations, decreasing as function...
Abstract. Dissolved surface active species, or surfactants, have a tendency to partition solution and thereby decrease tension. Activating cloud droplets large surface-to-volume ratios, the amount of surfactant molecules in them is limited. Therefore, unlike with macroscopic solutions, partitioning can effectively deplete droplet interior molecules. Surfactant equilibrium for activating has so far been solved numerically from group non-linear equations containing Gibbs adsorption equation...