Pallas cloud experiment, PaCE 2012

Brus, David; Neitola, Kimmo; Asmi, Eija; Aurela, Mika; Makkonen, Ulla; Svensson, Jonas; Hyvärinen, Antti; Hirsikkoa, A.; Hakola, Hannele; Hillamo, Risto; Lihavainen, Heikki

doi:10.1063/1.4803433

Cited by 5 publications

(3 citation statements)

References 8 publications

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“…Chilbolton is also a rural site, located in southern United Kingdom, 100 km WSW of London. The site is most frequently influenced by the marine air masses; a potential local source of anthropogenic pollution is the seasonal agricultural spraying (Campanelli et al, 2012). The Convective and Orographically-induced Precipitation Study (COPS) campaign took place at the top of the Hornisgrinde Mountain in the Black Forest region of south-west Germany.…”

Section: Measurement Sitesmentioning

confidence: 99%

A synthesis of cloud condensation nuclei counter (CCNC) measurements within the EUCAARI network

et al. 2015

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Published by Copernicus Publications on behalf of the European Geosciences Union. M. Paramonov et al.: A synthesis of CCNC measurements within the EUCAARI networkAbstract. Cloud condensation nuclei counter (CCNC) measurements performed at 14 locations around the world within the European Integrated project on Aerosol Cloud Climate and Air Quality interactions (EUCAARI) framework have been analysed and discussed with respect to the cloud condensation nuclei (CCN) activation and hygroscopic properties of the atmospheric aerosol. The annual mean ratio of activated cloud condensation nuclei (N CCN ) to the total number concentration of particles (N CN ), known as the activated fraction A, shows a similar functional dependence on supersaturation S at many locations -exceptions to this being certain marine locations, a free troposphere site and background sites in south-west Germany and northern Finland. The use of total number concentration of particles above 50 and 100 nm diameter when calculating the activated fractions (A 50 and A 100 , respectively) renders a much more stable dependence of A on S; A 50 and A 100 also reveal the effect of the size distribution on CCN activation. With respect to chemical composition, it was found that the hygroscopicity of aerosol particles as a function of size differs among locations. The hygroscopicity parameter κ decreased with an increasing size at a continental site in south-west Germany and fluctuated without any particular size dependence across the observed size range in the remote tropical North Atlantic and rural central Hungary. At all other locations κ increased with size. In fact, in Hyytiälä, Vavihill, Jungfraujoch and Pallas the difference in hygroscopicity between Aitken and accumulation mode aerosol was statistically significant at the 5 % significance level. In a boreal environment the assumption of a size-independent κ can lead to a potentially substantial overestimation of N CCN at S levels above 0.6 %. The same is true for other locations where κ was found to increase with size. While detailed information about aerosol hygroscopicity can significantly improve the prediction of N CCN , total aerosol number concentration and aerosol size distribution remain more important parameters. The seasonal and diurnal patterns of CCN activation and hygroscopic properties vary among three long-term locations, highlighting the spatial and temporal variability of potential aerosol-cloud interactions in various environments.

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Section: Measurement Sitesmentioning

confidence: 99%

A synthesis of cloud condensation nuclei counter (CCNC) measurements within the EUCAARI network

et al. 2015

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“…Fine particles at the Sammaltunturi are expected to be dominated by sulphate and particulate organic matter in continental air masses, while particulate organic matter, sodium and chlorine are the main components in marine air masses (Lihavainen et al, 2008, Brus et al, 2013a. Also, episodes of elevated concentrations of SO2 and H2SO4 are possible in air masses arriving from the Kola Peninsula, 185 which is a large source of SO2 emissions (Kyro et al, 2014;Sipilä et al, 2020, Brus et al, 2013a.…”

Section: Instrumentationmentioning

confidence: 99%

Influence of air mass origin on microphysical properties of low-level clouds in a subarctic environment

Doulgeris

Vakkari

O’Connor

et al. 2022

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Abstract. In this work, an analysis was performed to investigate how different long-range transport air masses can affect the occurrence and the microphysical properties of low-level clouds in a clean subarctic environment. The cloud measurements comprised in-situ and ground-based and were conducted during eight Pallas Cloud Experiments (PaCE) held in the autumn between 2004 and 2019. Each PaCE was carried out at the Pallas Atmosphere – Ecosystem Supersite, located in the Finnish subarctic region. Two cloud spectrometer ground setups were installed on the roof of the station to measure cloud microphysical properties: the Cloud, Aerosol and Precipitation Spectrometer probe (CAPS) and the Forward Scattering Spectrometer Probe (FSSP). Air mass histories were analyzed using the Lagrangian particle dispersion model FLEXPART in order to investigate the differences between five distinct source regions (Arctic, Eastern, Southern, Western and Local). The results showed that there was a connection between the microphysical properties of the clouds we sampled during PaCEs and the air mass source region. The occurrence of clouds at the measuring station was mainly connected with air masses coming from the continental regions. Higher values of cloud droplet number concentrations (Nc) were related to air masses coming from the Southern and Eastern regions (continental), whereas the lowest values of Nc were related to Arctic and Western air masses (marine). In addition, the marine air masses were characterized by larger cloud droplets (median volume diameter approximately from 15 to 20 µm), in comparison to continental air masses that were mainly characterized by cloud droplets with median volume diameters of approximately from 8 to 12 µm. Finally, there was an indication that cloud droplets were more prone to grow in warm liquid clouds.

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“…Fine particles at the Sammaltunturi site are expected to be dominated by sulfate and particulate organic matter in continental air masses, while particulate organic matter, sodium and chlorine are the main components in marine air masses Brus et al, 2013a). Also, episodes of elevated concentrations of SO 2 and H 2 SO 4 are possible in air masses arriving from the Kola Peninsula, which is a large source of SO 2 emissions (Kyrö et al, 2014;Sipilä et al, 2021;Brus et al, 2013a, b).…”

Section: Sampling Campaignsmentioning

confidence: 99%

Experimental studies on cloud condensation nuclei activation and cloud microphysical properties

Doulgeris¹

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Atmospheric aerosol particles have the ability to affect climate through cloud interactions and direct scattering and absorption of radiation. These aerosol particles can also affect human health through respiratory system. Aerosol particles are emitted to the atmosphere through direct sources or they can be formed through chemical processes from gas phase precursors. The different atmospheric processes and climate feedbacks of aerosol particles can be studied using process-scale models as well as larger global-scale models. In recent years, it has been found out that certain aerosol species lack information on their thermodynamic properties, causing uncertainties in process-scale modelling as well as global-scale modelling. In addition, transport of aerosols to remote regions, where emissions of aerosol particles are low, is poorly modelled in global-scale models. Furthermore, sources for formed secondary organic aerosol (SOA) include uncertainties in global aerosol-climate models, which causes uncertainty to estimating the radiative forcing (RF). In this thesis, these aspects relating to uncertainties are addressed using process and global-scale modelling. This was done first by evaluating the capability of thermodynamic equilibrium model to reproduce observed hygroscopicity in terms of dimethylamine, sulfuric acid and ammonia containing particles. Second, an in-cloud wet deposition scheme was developed (hereafter referred to as the newly-developed scheme) for global models which use sectional aerosol description. The newlydeveloped wet deposition scheme was tested using ECHAM-HAMMOZ global aerosol-climate model with Sectional Aerosol model for Large-Scale Applications (SALSA) in terms of aerosol vertical distributions and lifetimes. Third, the biotic stress effects to trees over boreal region and their effects to SOA formation, clouds and radiative effects were studied using ECHAM-HAMMOZ with SALSA. The results showed that when the thermodynamic equilibrium model was used to model particles with sizes of the order of couple of tens of nanometers, it was inadequate in estimating the hygroscopic growth of dimethylamine (DMA), sulfuric acid (SA) and ammonia containing particles. Thus, more investigation is needed in terms of thermodynamics of DMA containing systems to properly evaluate its effects to climate. Global aerosol-climate models are very complex and thus making aerosol processes more physically sound can even impair the results. This was seen in the results of the newly-developed, more physical, in-cloud wet deposition scheme as it produced spurious vertical profiles and atmospheric black carbon lifetime when compared to the preexisting scheme. Especially, the atmospheric lifetime of black carbon, in the newly-developed scheme, was 1.6 times longer than in the pre-existing scheme and over 2.6 times longer than has been suggested by experimental studies. Thus, the sensitivity of the newly-developed scheme was tested in terms of internal mixing and emission size distribution of black carbon as well as ageing of aerosol species. These results showed that mixing black carbon with soluble substances produced best results in comparison with the observations as well as atmospheric lifetimes of aerosol species when compared to AEROCOM model means. Lastly, the results studying the biotic stress effects on climate showed that increasing the extent of stress in boreal trees enhanced SOA formation as the emissions of volatile organic compounds (VOCs) were increased. The enhanced SOA formation increased cloud droplet number concentration (CDNC) at cloud top and caused stronger negative RF in both all-sky and clear-sky cases. In the future, aerosol model development should investigate further on the thermodynamic properties of aerosol species, especially with respect to DMA. The wet removal and extent of internal mixing of different aerosol species, especially black carbon, should be further investigated and revised, in global climate models, to properly evaluate the transport of aerosol particles. In addition, sources of atmospheric SOA needs further investigation to properly describe its behaviour in the atmosphere as well as the effects on the climate.

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Pallas cloud experiment, PaCE 2012

Cited by 5 publications

References 8 publications

A synthesis of cloud condensation nuclei counter (CCNC) measurements within the EUCAARI network

A synthesis of cloud condensation nuclei counter (CCNC) measurements within the EUCAARI network

Influence of air mass origin on microphysical properties of low-level clouds in a subarctic environment

Experimental studies on cloud condensation nuclei activation and cloud microphysical properties

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