| 1. |
- Asmi, A., et al.
(författare)
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Aerosol decadal trends - Part 2: In-situ aerosol particle number concentrations at GAW and ACTRIS stations
- 2013
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Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7324. ; 13:2, s. 895-916
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Tidskriftsartikel (refereegranskat)abstract
- We have analysed the trends of total aerosol particle number concentrations (N) measured at long-term measurement stations involved either in the Global Atmosphere Watch (GAW) and/or EU infrastructure project ACTRIS. The sites are located in Europe, North America, Antarctica, and on Pacific Ocean islands. The majority of the sites showed clear decreasing trends both in the full-length time series, and in the intra-site comparison period of 2001-2010, especially during the winter months. Several potential driving processes for the observed trends were studied, and even though there are some similarities between N trends and air temperature changes, the most likely cause of many northern hemisphere trends was found to be decreases in the anthropogenic emissions of primary particles, SO2 or some co-emitted species. We could not find a consistent agreement between the trends of N and particle optical properties in the few stations with long time series of all of these properties. The trends of N and the proxies for cloud condensation nuclei (CCN) were generally consistent in the few European stations where the measurements were available. This work provides a useful comparison analysis for modelling studies of trends in aerosol number concentrations.
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| 2. |
- Asmi, A., et al.
(författare)
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Number size distributions and seasonality of submicron particles in = rope 2008-2009
- 2011
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Ingår i: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 11:11, s. 5505-5538
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Tidskriftsartikel (refereegranskat)abstract
- Two years of harmonized aerosol number size distribution data from 24 = ropean field monitoring sites have been analysed. The results give a = mprehensive overview of the European near surface aerosol particle = mber concentrations and number size distributions between 30 and 500 = of dry particle diameter. Spatial and temporal distribution of = rosols in the particle sizes most important for climate applications = e presented. We also analyse the annual, weekly and diurnal cycles of = e aerosol number concentrations, provide log-normal fitting parameters = r median number size distributions, and give guidance notes for data = ers. Emphasis is placed on the usability of results within the aerosol = delling community.
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| 3. |
- Fors, Erik, et al.
(författare)
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Hygroscopic properties of the ambient aerosol in southern Sweden - a two year study
- 2011
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Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7324. ; 11:16, s. 8343-8361
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Tidskriftsartikel (refereegranskat)abstract
- The hygroscopic growth of the atmospheric aerosol is a critical parameter for quantifying the anthropogenic radiative forcing. Until now, there has been a lack of long term measurements due to limitations in instrumental techniques. In this work, for the first time the seasonal variation of the hygroscopic properties of a continental background aerosol has been described, based on more than two years of continuous measurements. In addition to this, the diurnal variation of the hygroscopic growth has been investigated, as well as the seasonal variation in CCN concentration. These physical properties of the aerosol have been measured with a Hygroscopic Tandem Differential Mobility Analyzer (H-TDMA), a Differential Mobility Particle Sizer (DMPS), and a Cloud Condensation Nuclei Counter (CCNC). The results show that smaller particles are generally less hygroscopic than larger ones, and that there is a clear difference in the hygroscopic properties between the Aitken and the accumulation mode. A seasonal cycle was found for all particle sizes. In general, the average hygroscopic growth is lower during wintertime, due to an increase in the relative abundance of less hygroscopic or barely hygroscopic particles. Monthly averages showed that the hygroscopic growth factors of the two dominating hygroscopic modes (one barely hygroscopic and one more hygroscopic) were relatively stable. The hygroscopic growth additionally showed a diurnal cycle, with higher growth factors during day time. CCN predictions based on H-TDMA data underpredicted the activated CCN number concentration with 7% for a 1% water supersaturation ratio. The underprediction increases with decreasing s, most likely due to a combination of measurement and modeling uncertainties. It was found that although the aerosol is often externally mixed, recalculating to an internal mixture with respect to hygroscopicity did not change the CCN concentration as a function of supersaturation significantly.
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| 4. |
- Hamburger, T., et al.
(författare)
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Overview of the synoptic and pollution situation over Europe during the EUCAARI-LONGREX field campaign
- 2011
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Ingår i: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 11:3, s. 1065-1082
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Tidskriftsartikel (refereegranskat)abstract
- In May 2008 the EUCAARI-LONGREX aircraft field campaign was conducted within the EUCAARI intensive observational period. The campaign aimed at studying the distribution and evolution of air mass properties on a continental scale. Airborne aerosol and trace gas measurements were performed aboard the German DLR Falcon 20 and the British FAAM BAe-146 aircraft. This paper outlines the meteorological situation over Europe during May 2008 and the temporal and spatial evolution of predominantly anthropogenic particulate pollution inside the boundary layer and the free troposphere. Time series data of six selected ground stations are used to discuss continuous measurements besides the single flights. The observations encompass total and accumulation mode particle number concentration (0.1–0.8 μm) and black carbon mass concentration as well as several meteorological parameters. Vertical profiles of total aerosol number concentration up to 10 km are compared to vertical profiles probed during previous studies.During the first half of May 2008 an anticyclonic blocking event dominated the weather over Central Europe. It led to increased pollutant concentrations within the centre of the high pressure inside the boundary layer. Due to long-range transport the accumulated pollution was partly advected towards Western and Northern Europe. The measured aerosol number concentrations over Central Europe showed in the boundary layer high values up to 14 000 cm−3 for particles in diameter larger 10 nm and 2300 cm−3 for accumulation mode particles during the high pressure period, whereas the middle free troposphere showed rather low concentrations of particulates. Thus a strong negative gradient of aerosol concentrations between the well mixed boundary layer and the clean middle troposphere occurred.
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| 5. |
- Kivekäs, Niku, et al.
(författare)
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Contribution of ship traffic to aerosol particle concentrations downwind of a major shipping lane
- 2014
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Ingår i: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 14:16, s. 8255-8267
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Tidskriftsartikel (refereegranskat)abstract
- Particles in the atmosphere are of concern due to their toxic properties and effects on climate. In coastal areas, ship emissions can be a significant anthropogenic source. In this study we investigated the contribution from ship emissions to the total particle number and mass concentrations at a remote location. We studied the particle number concentration (12 to 490 nm in diameter), the mass concentration (12 to 150 nm in diameter) and number and volume size distribution of aerosol particles in ship plumes for a period of 4.5 months at Hovsore, a coastal site on the western coast of Jutland in Denmark. During episodes of western winds, the site is about 50 km downwind of a major shipping lane and the plumes are approximately 1 hour old when they arrive at the site. We have used a sliding percentile-based method for separating the plumes from the measured background values and to calculate the ship plume contribution to the total particle number and PM0.15 mass concentration (mass of particles below 150 nm in diameter, converted from volume assuming sphericity) at the site. The method is not limited to particle number or volume concentration, but can also be used for different chemical species in both particle and gas phase. The total number of analyzed ship plumes was 726, covering on average 19% of the time when air masses were arriving at the site over the shipping lane. During the periods when plumes were present, the particle concentration exceeded the background values on average by 790 cm(-3) by number and 0.10 gm(-3) by mass. The corresponding daily average values were 170 cm-3 and 0.023 gm-3, respectively. This means that the ship plumes contributed between 11 and 19% to the particle number concentration and between 9 and 18% to PM0.15 during days when air was arriving over the shipping lane. The estimated annual contribution from ship plumes, where all wind directions were included, was in the range of 5-8% in particle number concentration and 4-8% in PM0.15.
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| 6. |
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| 7. |
- Kristensson, Adam, et al.
(författare)
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Cloud Droplet Activation of Amino Acid Aerosol Particles.
- 2010
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Ingår i: Journal of physical chemistry. A. - : American Chemical Society (ACS). - 1520-5215 .- 1089-5639. ; 114:1, s. 379-386
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Tidskriftsartikel (refereegranskat)abstract
- In this work we investigated the ability of a series of amino acids to act as cloud condensation nuclei using a static thermal gradient diffusion type cloud condensation nucleus counter. Particles of pure dry l-glycine, glycyl-glycine, l-serine, l-methionine, l-glutamic acid, l-aspartic acid, and l-tyrosine were studied as well as internally mixed dry particles containing ammonium sulfate and one or two of the following amino acids: l-methionine, l-aspartic acid, or l-tyrosine. The amino acids ranged in water solubility from high (>100 g/L), intermediate (10-100 g/L), low (3-10 g/L), to very low (<3 g/L). With the exception of l-methionine and l-tyrosine, all the studied pure amino acid particles activated as though they were fully soluble, although Kohler theory modified to account for limited solubility suggests that the activation of the intermediate and low solubility amino acids l-serine, l-glutamic acid, and l-aspartic acid should be limited by solubility. Activation of mixed particles containing at least 60% dry mass of l-tyrosine was limited by solubility, but the activation of the other investigated mixed particles behaved as if fully soluble. In general, the results show that particles containing amino acids at atmospherically relevant mixture ratios are good cloud condensation nuclei.
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| 8. |
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| 9. |
- Kristensson, Adam, et al.
(författare)
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NanoMap: Geographical mapping of atmospheric new-particle formation through analysis of particle number size distribution and trajectory data
- 2014
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Ingår i: Boreal Environment Research: An International Interdisciplinary Journal. - 1239-6095. ; 19, s. 329-342
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Tidskriftsartikel (refereegranskat)abstract
- Particle number size distributions at various field sites are used to identify atmospheric new-particle formation (NPF) event days. However, the spatial distribution of regionally extensive events is unknown. To remedy this situation, the NanoMap method has been developed to enable the estimation of where NPF occurs within 500 km from any field station using as input size distribution and meteorological trajectories only. Also, the horizontal extension of NPF can be determined. An open-source program to run NanoMap is available on the internet. NanoMap has been developed using as an example the Finnish field site at Hyytiala. It shows that there are frequent NPF events over the Baltic Sea, but not as frequent as over Finland for certain wind directions; hence NanoMap is able to pinpoint areas with a low or high occurrence of NPF events. The method should be applicable to almost any field site.
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| 10. |
- Kristensson, Adam
(författare)
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Partiklar i Malmöluften - Sammansättning, källor, hälsoeffekter, åtgärder
- 2011
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Rapport (populärvet., debatt m.m.)abstract
- En femtedel av befolkningen i Malmö exponeras i utomhusluften för masshalter av inandningsbara partiklar (PM10) som ligger över Sveriges miljömål för 2010. Resterande del exponeras för halter som är högre än lågrisknivån bedömd av Institutet för miljömedicin vid Karolinska institutet. Drygt 200 människor i Malmö stad beräknas dö i förtid varje år på grund av denna exponering. Malmö miljöförvaltning har i många år mätt masskoncentrationen av partiklar i Malmö, men ingen utredning har gjorts om varifrån partiklarna härstammar. Med anledning av detta har Lunds universitet fått i uppdrag av förvaltningen att ta fram underlag från olika vetenskapliga arbeten för att få svar på fyra grundläggande frågor: 1. Vad består Malmös partiklar av? 2. Vilka är källorna till Malmös partikelhalter? 3. Hur stor roll spelar intransport från kontinenten för halterna? 4. Vilka hälsoeffekter kan förväntas utifrån exponeringen? I förlängningen vill man ha svar på vilka riktade åtgärder som går att utföra för att få bukt med effekterna av exponeringen. Dessa frågor besvaras i denna rapport, som är riktad till Malmös kommunpolitiker och allmänheten. I korta drag visar rapporten att de som exponeras för de högsta PM10-halterna vistas vid hårt trafikerade gator, där de förhöjda halterna huvudsakligen beror på att asfaltpartiklar blir luftburna genom nötningen av asfalten av bilarna. Övriga partiklar som kommer från Malmö och som majoriteten av Malmöborna exponeras för, är från bilavgaserna. Den enskilt största källan i Malmö är dock långdistanstransport. I motsats till PM10, är det avgaspartiklar från Malmös egen biltrafik som dominerar bidragen till de förhöjda halterna av antalet partiklar i Malmö. Det är okänt om slitagepartiklarna ger upphov till förtida dödlighet, men man vet att de ger en ökad frekvens av astma och luftvägssjukdomar. Det är fina partiklar (PM2.5) som framförallt ger upphov till ökad dödlighet samt hjärt/kärlsjukdomar och det är troligt att det är avgaspartiklarna som är orsaken till detta. Hjärt/kärlsjukdomar och luftvägssjukdomar förefaller även vara kopplade till långdistanstransporterade partiklar. Riktade åtgärder mot asfaltpartiklar på de hårdast trafikerade gatorna i Malmö låter sig göras för att få bukt med de högsta PM10-halterna, medan åtgärder för hela stadens biltrafik är nödvändiga för att minska avgaspartiklarnas effekter. Flera olika åtgärdsstrategier, som Malmö kommun kan arbeta efter beskrivs i rapporten. Rapporten är uppdelad i en sammanfattande del samt i en längre del, med metodik, beräkningar av källtilldelningar och utförliga diskussioner kring hälsoeffekter och åtgärder.
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