Change search
Refine search result
1 - 16 of 16
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1. Boy, Michael
    et al.
    Thomson, Erik S.
    Acosta Navarro, Juan-C.
    Arnalds, Olafur
    Batchvarova, Ekaterina
    Back, Jaana
    Berninger, Frank
    Bilde, Merete
    Brasseur, Zoe
    Dagsson-Waldhauserova, Pavla
    Castarede, Dimitri
    Dalirian, Maryam
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    de Leeuw, Gerrit
    Dragosics, Monika
    Duplissy, Ella-Maria
    Duplissy, Jonathan
    Ekman, Annica M. L.
    Stockholm University, Faculty of Science, Department of Meteorology .
    Fang, Keyan
    Gallet, Jean-Charles
    Glasius, Marianne
    Gryning, Sven-Erik
    Grythe, Henrik
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. NILU–Norwegian Institute for Air Research, Norway.
    Hansson, Hans-Christen
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Hansson, Margareta
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Isaksson, Elisabeth
    Iversen, Trond
    Jonsdottir, Ingibjorg
    Kasurinen, Ville
    Kirkevag, Alf
    Korhola, Atte
    Krejci, Radovan
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Kristjansson, Jon Egill
    Lappalainen, Hanna K.
    Lauri, Antti
    Lepparanta, Matti
    Lihavainen, Heikki
    Makkonen, Risto
    Massling, Andreas
    Meinander, Outi
    Nilsson, E. Douglas
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Olafsson, Haraldur
    Pettersson, Jan B. C.
    Prisle, Nonne L.
    Riipinen, Ilona
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Roldin, Pontus
    Ruppel, Meri
    Salter, Matthew
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Sand, Maria
    Seland, Oyvind
    Seppa, Heikki
    Skov, Henrik
    Soares, Joana
    Stohl, Andreas
    Ström, Johan
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Svensson, Jonas
    Swietlicki, Erik
    Tabakova, Ksenia
    Thorsteinsson, Throstur
    Virkkula, Aki
    Weyhenmeyer, Gesa A.
    Wu, Yusheng
    Zieger, Paul
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Kulmala, Markku
    Interactions between the atmosphere, cryosphere, and ecosystems at northern high latitudes2019In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 19, no 3, p. 2015-2061Article in journal (Refereed)
    Abstract [en]

    The Nordic Centre of Excellence CRAICC (Cryosphere-Atmosphere Interactions in a Changing Arctic Climate), funded by NordForsk in the years 2011-2016, is the largest joint Nordic research and innovation initiative to date, aiming to strengthen research and innovation regarding climate change issues in the Nordic region. CRAICC gathered more than 100 scientists from all Nordic countries in a virtual centre with the objectives of identifying and quantifying the major processes controlling Arctic warming and related feedback mechanisms, outlining strategies to mitigate Arctic warming, and developing Nordic Earth system modelling with a focus on short-lived climate forcers (SLCFs), including natural and anthropogenic aerosols. The outcome of CRAICC is reflected in more than 150 peer-reviewed scientific publications, most of which are in the CRAICC special issue of the journal Atmospheric Chemistry and Physics. This paper presents an overview of the main scientific topics investigated in the centre and provides the reader with a state-of-the-art comprehensive summary of what has been achieved in CRAICC with links to the particular publications for further detail. Faced with a vast amount of scientific discovery, we do not claim to completely summarize the results from CRAICC within this paper, but rather concentrate here on the main results which are related to feedback loops in climate change-cryosphere interactions that affect Arctic amplification.

  • 2.
    Burgos, María A.
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Andrews, Elisabeth
    Titos, Gloria
    Alados-Arboledas, Lucas
    Baltensperger, Urs
    Day, Derek
    Jefferson, Anne
    Kalivitis, Nikos
    Mihalopoulos, Nikos
    Sherman, James
    Sun, Junying
    Weingartner, Ernest
    Zieger, Paul
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    A global view on the effect of water uptake on aerosol particle light scattering2019In: Scientific Data, E-ISSN 2052-4463, Vol. 6, article id 157Article in journal (Refereed)
    Abstract [en]

    A reference dataset of multi-wavelength particle light scattering and hemispheric backscattering coefficients for different relative humidities (RH) between RH = 30 and 95% and wavelengths between lambda = 450 nm and 700 nm is described in this work. Tandem-humidified nephelometer measurements from 26 ground-based sites around the globe, covering multiple aerosol types, have been re-analysed and harmonized into a single dataset. The dataset includes multi-annual measurements from long-term monitoring sites as well as short-term field campaign data. The result is a unique collection of RH-dependent aerosol light scattering properties, presented as a function of size cut. This dataset is important for climate and atmospheric model-measurement inter-comparisons, as a means to improve model performance, and may be useful for satellite and remote sensing evaluation using surface-based, in-situ measurements.

  • 3.
    Franke, Vera
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. Swedish University of Agricultural Sciences, Sweden.
    Zieger, Paul
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Wideqvist, Ulla
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Acosta Navarro, Juan Camilo
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. Barcelona Supercomputing Center, Spain.
    Leck, Caroline
    Stockholm University, Faculty of Science, Department of Meteorology .
    Tunved, Peter
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Rosati, Bernadette
    Gysel, Martin
    Salter, Matthew Edward
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Ström, Johan
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Chemical composition and source analysis of carbonaceous aerosol particles at a mountaintop site in central Sweden2017In: Tellus. Series B, Chemical and physical meteorology, ISSN 0280-6509, E-ISSN 1600-0889, Vol. 69, article id 1353387Article in journal (Refereed)
    Abstract [en]

    The chemical composition of atmospheric particulate matter at Mt. angstrom reskutan, a mountaintop site in central Sweden, was analysed with a focus on its carbonaceous content. Filter samples taken during the Cloud and Aerosol Experiment at angstrom re (CAEsAR 2014) were analysed by means of a thermo-optical method and ion chromatography. Additionally, the particle light absorption and particle number size distribution measurements for the entire campaign were added to the analysis. Mean airborne concentrations of organic and elemental carbon during CAEsAR 2014 were OC= 0.85 +/- 0.8 mu gm(-3) and EC = 0.06 +/- 0.06 mu gm(-3), respectively. Elemental to organic carbon ratios varied between EC/OC = 0.02 and 0.19. During the study a large wildfire occurred in Vastmanland, Sweden, with the plume reaching our study site. This led to significant increases in OC and EC concentrations (OC = 3.04 +/- 0.03 mu gm(-3) and EC = 0.24 +/- 0.00 mu gm(-3)). The mean mass-specific absorption coefficient observed during the campaign was sigma(BC)(abs) = 9.1 +/- 7.3 m(2)g(-1) (at wavelength lambda= 637 nm). In comparison to similarly remote European sites, Mt. angstrom reskutan experienced significantly lower carbonaceous aerosol loadings with a clear dominance of organic carbon. A mass closure study revealed a missing chemical mass fraction that likely originated from mineral dust. Potential regional source contributions of the carbonaceous aerosol were investigated using modelled air mass back trajectories. This source apportionment pointed to a correlation between high EC concentrations and air originating from continental Europe. Particles rich in organic carbon most often arrived from highly vegetated continental areas. However, marine regions were also a source of these aerosol particles. The source contributions derived during this study were compared to emission inventories of an Earth system model. This comparison highlighted a lack of OC and EC point-sources in the model's emission inventory which could potentially lead to an underestimation of the carbonaceous aerosol reaching Mt. angstrom reskutan in the simulation of this Earth system model.

  • 4.
    Haslett, Sophie L.
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. University of Manchester, UK.
    Taylor, Jonathan W.
    Deetz, Konrad
    Vogel, Bernhard
    Babic, Karmen
    Kalthoff, Norbert
    Wieser, Andreas
    Dione, Cheikh
    Lohou, Fabienne
    Brito, Joel
    Dupuy, Regis
    Schwarzenboeck, Alfons
    Zieger, Paul
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Coe, Hugh
    The radiative impact of out-of-cloud aerosol hygroscopic growth during the summer monsoon in southern West Africa2019In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 19, no 3, p. 1505-1520Article in journal (Refereed)
    Abstract [en]

    Water in the atmosphere can exist in the solid, liquid or gas phase. At high humidities, if the aerosol population remains constant, more water vapour will condense onto the particles and cause them to swell, sometimes up to several times their original size. This significant change in size and chemical composition is termed hygroscopic growth and alters a particle's optical properties. Even in unsaturated conditions, this can change the aerosol direct effect, for example by increasing the extinction of incoming sunlight. This can have an impact on a region's energy balance and affect visibility. Here, aerosol and relative humidity measurements collected from aircraft and radiosondes during the Dynamics-Aerosol-Chemistry-Cloud Interactions in West Africa (DACCIWA) campaign were used to estimate the effect of highly humid layers of air on aerosol optical properties during the monsoon season in southern West Africa. The effects of hygroscopic growth in this region are of particular interest due to the regular occurrence of high humidity and the high levels of pollution in the region. The Zdanovskii, Stokes and Robinson (ZSR) mixing rule is used to estimate the hygroscopic growth of particles under different conditions based on chemical composition. These results are used to estimate the aerosol optical depth (AOD) at lambda = 525 nm for 63 relative humidity profiles. The median AOD in the region from these calculations was 0.36, the same as that measured by sun photometers at the ground site. The spread in the calculated AODs was less than the spread from the sun photometer measurements. In both cases, values above 0.5 were seen predominantly in the mornings and corresponded with high humidities. Observations of modest variations in aerosol load and composition are unable to explain the high and variable AODs observed using sun photometers, which can only be recreated by accounting for the very elevated and variable relative humidities (RHs) in the boundary layer. Most importantly, the highest AODs present in the mornings are not possible without the presence of high RH in excess of 95 %. Humid layers are found to have the most significant impact on AOD when they reach RH greater than 98 %, which can result in a wet AOD more than 1.8 times the dry AOD. Unsaturated humid layers were found to reach these high levels of RH in 37% of observed cases. It can therefore be concluded that the high AODs present across the region are driven by the high humidities and are then moderated by changes in aerosol abundance. Aerosol concentrations in southern West Africa are projected to increase substantially in the coming years; results presented here show that the presence of highly humid layers in the region is likely to enhance the consequent effect on AOD significantly.

  • 5. Ketterer, C.
    et al.
    Zieger, Paul
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM). Paul Scherrer Institute, Switzerland .
    Bukowiecki, N.
    Coen, M. Collaud
    Maier, O.
    Ruffieux, D.
    Weingartner, E.
    Investigation of the Planetary Boundary Layer in the Swiss Alps Using Remote Sensing and In Situ Measurements2014In: Boundary-layer Meteorology, ISSN 0006-8314, E-ISSN 1573-1472, Vol. 151, no 2, p. 317-334Article in journal (Refereed)
    Abstract [en]

    The development of the planetary boundary layer (PBL) has been studied in a complex terrain using various remote sensing and in situ techniques. The high-altitude research station at Jungfraujoch (3,580 m a.s.l.) in the Swiss Alps lies for most of the time in the free troposphere except when it is influenced by the PBL reaching the station, especially during the summer season. A ceilometer and a wind profiler were installed at Kleine Scheidegg, a mountain pass close to Jungfraujoch, located at an altitude of 2,061 m a.s.l. Data from the ceilometer were analyzed using two different algorithms, while the signal-to-noise ratio of the wind profiler was studied to compare the retrieved PBL heights. The retrieved values from the ceilometer and wind profiler agreed well during daytime and cloud-free conditions. The results were additionally compared with the PBL height estimated by the numerical weather prediction model COSMO-2, which showed a clear underestimation of the PBL height for most of the cases but occasionally also a slight overestimation especially around noon, when the PBL showed its maximum extent. Air parcels were transported upwards by slope winds towards Jungfraujoch when the PBL was higher than 2,800 m a.s.l. during cloud-free cases. This was confirmed by the in situ aerosol measurements at Jungfraujoch with a significant increase in particle number concentration, particle light absorption and scattering coefficients when PBL-influenced air masses reached the station in the afternoon hours. The continuous aerosol in situ measurements at Jungfraujoch were clearly influenced by the local PBL development but also by long-range transport phenomena such as Saharan dust or pollution from the south.

  • 6.
    Rastak, Narges
    et al.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Silvergren, S.
    Zieger, Paul
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Wideqvist, Ulla
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Ström, Johan
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Svenningsson, B.
    Maturilli, M.
    Tesche, Matthias
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Ekman, Annica M. L.
    Stockholm University, Faculty of Science, Department of Meteorology .
    Tunved, Peter
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Riipinen, Ilona
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Seasonal variation of aerosol water uptake and its impact on the direct radiative effect at Ny-Alesund, Svalbard2014In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 14, no 14, p. 7445-7460Article in journal (Refereed)
    Abstract [en]

    In this study we investigated the impact of water uptake by aerosol particles in ambient atmosphere on their optical properties and their direct radiative effect (ADRE, W m(-2)) in the Arctic at Ny-Alesund, Svalbard, during 2008. To achieve this, we combined three models, a hygroscopic growth model, a Mie model and a radiative transfer model, with an extensive set of observational data. We found that the seasonal variation of dry aerosol scattering coefficients showed minimum values during the summer season and the beginning of fall (July-August-September), when small particles (< 100 nm in diameter) dominate the aerosol number size distribution. The maximum scattering by dry particles was observed during the Arctic haze period (March-April-May) when the average size of the particles was larger. Considering the hygroscopic growth of aerosol particles in the ambient atmosphere had a significant impact on the aerosol scattering coefficients: the aerosol scattering coefficients were enhanced by on average a factor of 4.30 +/- 2.26 (mean +/- standard deviation), with lower values during the haze period (March-April-May) as compared to summer and fall. Hygroscopic growth of aerosol particles was found to cause 1.6 to 3.7 times more negative ADRE at the surface, with the smallest effect during the haze period (March-April-May) and the highest during late summer and beginning of fall (July-August-September).

  • 7. Renard, Jean-Baptiste
    et al.
    Dulac, Francois
    Berthet, Gwenael
    Lurton, Thibaut
    Vignelles, Damien
    Jegou, Fabrice
    Tonnelier, Thierry
    Jeannot, Matthieu
    Coute, Benoit
    Akiki, Rony
    Verdier, Nicolas
    Mallet, Marc
    Gensdarmes, Francois
    Charpentier, Patrick
    Mesmin, Samuel
    Duverger, Vincent
    Dupont, Jean-Charles
    Elias, Thierry
    Crenn, Vincent
    Sciare, Jean
    Zieger, Paul
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Salter, Matthew
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Roberts, Tjarda
    Giacomoni, Jerome
    Gobbi, Matthieu
    Hamonou, Eric
    Olafsson, Haraldur
    Dagsson-Waldhauserova, Pavla
    Camy-Peyret, Claude
    Mazel, Christophe
    Decamps, Thierry
    Piringer, Martin
    Surcin, Jeremy
    Daugeron, Daniel
    LOAC: a small aerosol optical counter/sizer for ground-based and balloon measurements of the size distribution and nature of atmospheric particles - Part 12016In: Atmospheric Measurement Techniques, ISSN 1867-1381, E-ISSN 1867-8548, Vol. 9, no 4, p. 1721-1742Article in journal (Refereed)
    Abstract [en]

    The study of aerosols in the troposphere and in the stratosphere is of major importance both for climate and air quality studies. Among the numerous instruments available, optical aerosol particles counters (OPCs) provide the size distribution in diameter range from about 100 nm to a few tens of mu m. Most of them are very sensitive to the nature of aerosols, and this can result in significant biases in the retrieved size distribution. We describe here a new versatile optical particle/sizer counter named LOAC (Light Optical Aerosol Counter), which is light and compact enough to perform measurements not only at the surface but under all kinds of balloons in the troposphere and in the stratosphere. LOAC is an original OPC performing observations at two scattering angles. The first one is around 12 degrees, and is almost insensitive to the refractive index of the particles; the second one is around 60 degrees and is strongly sensitive to the refractive index of the particles. By combining measurement at the two angles, it is possible to retrieve the size distribution between 0.2 and 100 mu m and to estimate the nature of the dominant particles (droplets, carbonaceous, salts and mineral particles) when the aerosol is relatively homogeneous. This typology is based on calibration charts obtained in the laboratory. The uncertainty for total concentrations measurements is +/- 20% when concentrations are higher than 1 particle cm 3 (for a 10 min integration time). For lower concentrations, the uncertainty is up to about +/- 60% for concentrations smaller than 10 2 particle cm(-3). Also, the uncertainties in size calibration are +/- 0.025 mu m for particles smaller than 0.6 mu m, 5% for particles in the 0.7-2 mu m range, and 10% for particles greater than 2 mu m. The measurement accuracy of sub-micronic particles could be reduced in a strongly turbid case when concentration of particles > 3 mu m exceeds a few particles cm(-3). Several campaigns of cross-comparison of LOAC with other particle counting instruments and remote sensing photometers have been conducted to validate both the size distribution derived by LOAC and the retrieved particle number density. The typology of the aerosols has been validated in well-defined conditions including urban pollution, desert dust episodes, sea spray, fog, and cloud. Comparison with reference aerosol mass monitoring instruments also shows that the LOAC measurements can be successfully converted to mass concentrations.

  • 8. Renard, Jean-Baptiste
    et al.
    Dulac, Francois
    Berthet, Gwenael
    Lurton, Thibaut
    Vignelles, Damien
    Jegou, Fabrice
    Tonnelier, Thierry
    Jeannot, Matthieu
    Coute, Benoit
    Akiki, Rony
    Verdier, Nicolas
    Mallet, Marc
    Gensdarmes, Francois
    Charpentier, Patrick
    Mesmin, Samuel
    Duverger, Vincent
    Dupont, Jean-Charles
    Elias, Thierry
    Crenn, Vincent
    Sciare, Jean
    Zieger, Paul
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Salter, Matthew
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Roberts, Tjarda
    Giacomoni, Jerome
    Gobbi, Matthieu
    Hamonou, Eric
    Olafsson, Haraldur
    Dagsson-Waldhauserova, Pavla
    Camy-Peyret, Claude
    Mazel, Christophe
    Decamps, Thierry
    Piringer, Martin
    Surcin, Jeremy
    Daugeron, Daniel
    LOAC: a small aerosol optical counter/sizer for ground-based and balloon measurements of the size distribution and nature of atmospheric particles - Part 22016In: Atmospheric Measurement Techniques, ISSN 1867-1381, E-ISSN 1867-8548, Vol. 9, no 8, p. 3673-3686Article in journal (Refereed)
    Abstract [en]

    In the companion (Part I) paper, we have described and evaluated a new versatile optical particle counter/sizer named LOAC (Light Optical Aerosol Counter), based on scattering measurements at angles of 12 and 60A degrees. That allows for some typology identification of particles (droplets, carbonaceous, salts, and mineral dust) in addition to size-segregated counting in a large diameter range from 0.2aEuro-A mu m up to possibly more than 100aEuro-A mu m depending on sampling conditions (Renard et al., 2016). Its capabilities overpass those of preceding optical particle counters (OPCs) allowing the characterization of all kind of aerosols from submicronic-sized absorbing carbonaceous particles in polluted air to very coarse particles (> 10-20aEuro-A mu m in diameter) in desert dust plumes or fog and clouds. LOAC's light and compact design allows measurements under all kinds of balloons, on-board unmanned aerial vehicles (UAVs) and at ground level. We illustrate here the first LOAC airborne results obtained from a UAV and a variety of scientific balloons. The UAV was deployed in a peri-urban environment near Bordeaux in France. Balloon operations include (i) tethered balloons deployed in urban environments in Vienna (Austria) and Paris (France), (ii) pressurized balloons drifting in the lower troposphere over the western Mediterranean (during the Chemistry-Aerosol Mediterranean Experiment - ChArMEx campaigns), (iii) meteorological sounding balloons launched in the western Mediterranean region (ChArMEx) and from Aire-sur-l'Adour in south-western France (VOLTAIRE-LOAC campaign). More focus is put on measurements performed in the Mediterranean during (ChArMEx) and especially during African dust transport events to illustrate the original capability of balloon-borne LOAC to monitor in situ coarse mineral dust particles. In particular, LOAC has detected unexpected large particles in desert sand plumes.

  • 9.
    Salter, Matthew E.
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Zieger, Paul
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Acosta Navarro, Juan Camilo
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Grythe, Henrik
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. Norwegian Institute for Air Research, Norway; Finnish Meteorological Institute, Finland.
    Kirkevag, A.
    Rosati, B.
    Riipinen, Ilona
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Nilsson, E. Douglas
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    An empirically derived inorganic sea spray source function incorporating sea surface temperature2015In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 15, no 19, p. 11047-11066Article in journal (Refereed)
    Abstract [en]

    We have developed an inorganic sea spray source function that is based upon state-of-the-art measurements of sea spray aerosol production using a temperature-controlled plunging jet sea spray aerosol chamber. The size-resolved particle production was measured between 0.01 and 10 mu m dry diameter. Particle production decreased non-linearly with increasing seawater temperature (between -1 and 30 degrees C) similar to previous findings. In addition, we observed that the particle effective radius, as well as the particle surface, particle volume and particle mass, increased with increasing seawater temperature due to increased production of particles with dry diameters greater than 1 mu m. By combining these measurements with the volume of air entrained by the plunging jet we have determined the size-resolved particle flux as a function of air entrainment. Through the use of existing parameterisations of air entrainment as a function of wind speed, we were subsequently able to scale our laboratory measurements of particle production to wind speed. By scaling in this way we avoid some of the difficulties associated with defining the white area of the laboratory whitecap - a contentious issue when relating laboratory measurements of particle production to oceanic whitecaps using the more frequently applied whitecap method. The here-derived inorganic sea spray source function was implemented in a Lagrangian particle dispersion model (FLEXPART - FLEXible PARTicle dispersion model). An estimated annual global flux of inorganic sea spray aerosol of 5.9 +/- 0.2 Pg yr(-1) was derived that is close to the median of estimates from the same model using a wide range of existing sea spray source functions. When using the source function derived here, the model also showed good skill in predicting measurements of Na+ concentration at a number of field sites further underlining the validity of our source function. In a final step, the sensitivity of a large-scale model (NorESM - the Norwegian Earth System Model) to our new source function was tested. Compared to the previously implemented parameterisation, a clear decrease of sea spray aerosol number flux and increase in aerosol residence time was observed, especially over the Southern Ocean. At the same time an increase in aerosol optical depth due to an increase in the number of particles with optically relevant sizes was found. That there were noticeable regional differences may have important implications for aerosol optical properties and number concentrations, subsequently also affecting the indirect radiative forcing by non-sea spray anthropogenic aerosols.

  • 10.
    Salter, Matthew E.
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Hamacher-Barth, Evelyne
    Stockholm University, Faculty of Science, Department of Meteorology .
    Leck, Caroline
    Stockholm University, Faculty of Science, Department of Meteorology .
    Werner, J.
    Johnson, C. M.
    Riipinen, Ilona
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Nilsson, E. Douglas
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Zieger, Paul
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Calcium enrichment in sea spray aerosol particles2016In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 43, no 15, p. 8277-8285Article in journal (Refereed)
    Abstract [en]

    Sea spray aerosol particles are an integral part of the Earth's radiation budget. To date, the inorganic composition of nascent sea spray aerosol particles has widely been assumed to be equivalent to the inorganic composition of seawater. Here we challenge this assumption using a laboratory sea spray chamber containing both natural and artificial seawater, as well as with ambient aerosol samples collected over the central Arctic Ocean during summer. We observe significant enrichment of calcium in submicrometer (<1m in diameter) sea spray aerosol particles when particles are generated from both seawater sources in the laboratory as well as in the ambient aerosols samples. We also observe a tendency for increasing calcium enrichment with decreasing particle size. Our results suggest that calcium enrichment in sea spray aerosol particles may be environmentally significant with implications for our understanding of sea spray aerosol, its impact on Earth's climate, as well as the chemistry of the marine atmosphere.

  • 11.
    Tesche, Matthias
    et al.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Zieger, Paul
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Rastak, Narges
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Charlson, R. J.
    Glantz, Paul
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Tunved, Peter
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Hansson, Hans-Christen
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Reconciling aerosol light extinction measurements from spaceborne lidar observations and in situ measurements in the Arctic2014In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 14, no 15, p. 7869-7882Article in journal (Refereed)
    Abstract [en]

    In this study we investigate to what degree it is possible to reconcile continuously recorded particle light extinction coefficients derived from dry in situ measurements at Zeppelin station (78.92 degrees N, 11.85 degrees E; 475 m above sea level), Ny-lesund, Svalbard, that are recalculated to ambient relative humidity, as well as simultaneous ambient observations with the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) aboard the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite. To our knowledge, this represents the first study that compares spaceborne lidar measurements to optical aerosol properties from short-term in situ observations (averaged over 5 h) on a case-by-case basis. Finding suitable comparison cases requires an elaborate screening and matching of the CALIOP data with respect to the location of Zeppelin station as well as the selection of temporal and spatial averaging intervals for both the ground-based and spaceborne observations. Reliable reconciliation of these data cannot be achieved with the closest-approach method, which is often used in matching CALIOP observations to those taken at ground sites. This is due to the transport pathways of the air parcels that were sampled. The use of trajectories allowed us to establish a connection between spaceborne and ground-based observations for 57 individual overpasses out of a total of 2018 that occurred in our region of interest around Svalbard (0 to 25 degrees E, 75 to 82 degrees N) in the considered year of 2008. Matches could only be established during winter and spring, since the low aerosol load during summer in connection with the strong solar background and the high occurrence rate of clouds strongly influences the performance and reliability of CALIOP observations. Extinction coefficients in the range of 2 to 130 Mm(-1) at 532 nm were found for successful matches with a difference of a factor of 1.47 (median value for a range from 0.26 to 11.2) between the findings of in situ and spaceborne observations (the latter being generally larger than the former). The remaining difference is likely to be due to the natural variability in aerosol concentration and ambient relative humidity, an insufficient representation of aerosol particle growth, or a misclassification of aerosol type (i.e., choice of lidar ratio) in the CALIPSO retrieval.

  • 12. Titos, G.
    et al.
    Cazorla, A.
    Zieger, Paul
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Andrews, E.
    Lyamani, H.
    Granados-Munoz, M. J.
    Olmo, F. J.
    Alados-Arboledas, L.
    Effect of hygroscopic growth on the aerosol light-scattering coefficient: A review of measurements, techniques and error sources2016In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 141, p. 494-507Article, review/survey (Refereed)
    Abstract [en]

    Knowledge of the scattering enhancement factor,.f(RH), is important for an accurate description of direct aerosol radiative forcing. This factor is defined as the ratio between the scattering coefficient at enhanced relative humidity, RH, to a reference (dry) scattering coefficient. Here, we review the different experimental designs used to measure the scattering coefficient at dry and humidified conditions as well as the procedures followed to analyze the measurements. Several empirical parameterizations for the relationship between f(RH) and RH have been proposed in the literature. These parameterizations have been reviewed and tested using experimental data representative of different hygroscopic growth behavior and a new parameterization is presented. The potential sources of error in f(RH) are discussed. A Monte Carlo method is used to investigate the overall measurement uncertainty, which is found to be around 20-40% for moderately hygroscopic aerosols. The main factors contributing to this uncertainty are the uncertainty in RH measurement, the dry reference state and the nephelometer uncertainty. A literature survey of nephelometry-based f(RH) measurements is presented as a function of aerosol type. In general, the highest f(RH) values were measured in clean marine environments, with pollution having a major influence on f(RH). Dust aerosol tended to have the lowest reported hygroscopicity of any of the aerosol types studied. Major open questions and suggestions for future research priorities are outlined.

  • 13.
    Zieger, Paul
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Aalto, P. P.
    Aaltonen, V.
    Aijala, M.
    Backman, J.
    Hong, J.
    Komppula, M.
    Krejci, Radovan
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. University of Helsinki, Finland.
    Laborde, M.
    Lampilahti, J.
    de Leeuw, G.
    Pfuller, A.
    Rosati, B.
    Tesche, Matthias
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Tunved, Peter
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Vaananen, R.
    Petaja, T.
    Low hygroscopic scattering enhancement of boreal aerosol and the implications for a columnar optical closure study2015In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 15, no 13, p. 7247-7267Article in journal (Refereed)
    Abstract [en]

    Ambient aerosol particles can take up water and thus change their optical properties depending on the hygroscopicity and the relative humidity (RH) of the surrounding air. Knowledge of the hygroscopicity effect is of crucial importance for radiative forcing calculations and is also needed for the comparison or validation of remote sensing or model results with in situ measurements. Specifically, particle light scattering depends on RH and can be described by the scattering enhancement factor f(RH), which is defined as the particle light scattering coefficient at defined RH divided by its dry value (RH < 30-40 %). Here, we present results of an intensive field campaign carried out in summer 2013 at the SMEAR II station at Hyytiala, Finland. Ground-based and airborne measurements of aerosol optical, chemical and microphysical properties were conducted. The f(RH) measured at ground level by a humidified nephelometer is found to be generally lower (e.g. 1.63 +/- 0.22 at RH = 85% and lambda = 525 nm) than observed at other European sites. One reason is the high organic mass fraction of the aerosol encountered at Hyytiala to which f(RH) is clearly anti-correlated (R-2 approximate to 0.8). A simplified parametrization of f(RH) based on the measured chemical mass fraction can therefore be derived for this aerosol type. A trajectory analysis revealed that elevated values of f(RH) and the corresponding elevated inorganic mass fraction are partially caused by transported hygroscopic sea spray particles. An optical closure study shows the consistency of the ground-based in situ measurements. Our measurements allow to determine the ambient particle light extinction coefficient using the measured f(RH). By combining the ground-based measurements with intensive aircraft measurements of the particle number size distribution and ambient RH, columnar values of the particle extinction coefficient are determined and compared to columnar measurements of a co-located AERONET sun photometer. The water uptake is found to be of minor importance for the column-averaged properties due to the low particle hygroscopicity and the low RH during the daytime of the summer months. The in situ derived aerosol optical depths (AOD) clearly correlate with directly measured values of the sun photometer but are substantially lower compared to the directly measured values (factor of similar to 2-3). The comparison degrades for longer wavelengths. The disagreement between in situ derived and directly measured AOD is hypothesized to originate from losses of coarse and fine mode particles through dry deposition within the canopy and losses in the in situ sampling lines. In addition, elevated aerosol layers (above 3 km) from long-range transport were observed using an aerosol lidar at Kuopio, Finland, about 200 km east-northeast of Hyytiala. These elevated layers further explain parts of the disagreement.

  • 14.
    Zieger, Paul
    et al.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM). Paul Scherrer Institute.
    Fierz-Schmidhauser, R.
    Weingartner, E.
    Baltensperger, U.
    Effects of relative humidity on aerosol light scattering: results from different European sites2013In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 13, no 21, p. 10609-10631Article in journal (Refereed)
    Abstract [en]

    The effect of aerosol water uptake on the aerosol particle light scattering coefficient (sigma(sp)) is described in this study by comparing measurements from five European sites: the Jungfraujoch, located in the Swiss Alps at 3580 m a.s.l.; Ny-angstrom lesund, located on Spitsbergen in the Arctic; Mace Head, a coastal site in Ireland; Cabauw, a rural site in the Netherlands; and Melpitz, a regional background site in Eastern Germany. These sites were selected according to the aerosol type usually encountered at that location. The scattering enhancement factor f(RH, lambda) is the key parameter to describe the effect of water uptake on the particle light scattering. It is defined as the sigma(sp)(RH) at a certain relative humidity (RH) and wavelength lambda divided by its dry value. f(RH) at the five sites varied widely, starting at very low values of f(RH = 85%, lambda = 550 nm) around 1.28 for mineral dust, and reaching up to 3.41 for Arctic aerosol. Hysteresis behavior was observed at all sites except at the Jungfraujoch (due to the absence of sea salt). Closure studies and Mie simulations showed that both size and chemical composition determine the magnitude of f(RH). Both parameters are also needed to successfully predict f(RH). Finally, the measurement results were compared to the widely used aerosol model, OPAC (Hess et al., 1998). Significant discrepancies were seen, especially at intermediate RH ranges; these were mainly attributed to inappropriate implementation of hygroscopic growth in the OPAC model. Replacement of the hygroscopic growth with values from the recent literature resulted in a clear improvement of the OPAC model.

  • 15.
    Zieger, Paul
    et al.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM). Paul Scherrer Institute, Switzerland .
    Fierz-Schmidhauser, Rahel
    Poulain, Laurent
    Mueller, Thomas
    Birmili, Wolfram
    Spindler, Gerald
    Wiedensohler, Alfred
    Baltensperger, Urs
    Weingartner, Ernest
    Influence of water uptake on the aerosol particle light scattering coefficients of the Central European aerosol2014In: Tellus. Series B, Chemical and physical meteorology, ISSN 0280-6509, E-ISSN 1600-0889, Vol. 66, p. 22716-Article in journal (Refereed)
    Abstract [en]

    The influence of aerosol water uptake on the aerosol particle light scattering was examined at the regional continental research site Melpitz, Germany. The scattering enhancement factor f(RH), defined as the aerosol particle scattering coefficient at a certain relative humidity (RH) divided by its dry value, was measured using a humidified nephelometer. The chemical composition and other microphysical properties were measured in parallel. f(RH) showed a strong variation, e.g. with values between 1.2 and 3.6 at RH = 85% and lambda = 550 nm. The chemical composition was found to be the main factor determining the magnitude of f(RH), since the magnitude of f(RH) clearly correlated with the inorganic mass fraction measured by an aerosol mass spectrometer (AMS). Hysteresis within the recorded humidograms was observed and explained by long-range transported sea salt. A closure study using Mie theory showed the consistency of the measured parameters.

  • 16.
    Zieger, Paul
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Vaisanen, O.
    Corbin, J. C.
    Partridge, Dan G.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Bastelberger, S.
    Mousavi-Fard, M.
    Rosati, B.
    Gysel, M.
    Krieger, U. K.
    Leck, Caroline
    Stockholm University, Faculty of Science, Department of Meteorology .
    Nenes, A.
    Riipinen, Ilona
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Virtanen, A.
    Salter, Matthew E.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Revising the hygroscopicity of inorganic sea salt particles2017In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 8, article id 15883Article in journal (Refereed)
    Abstract [en]

    Sea spray is one of the largest natural aerosol sources and plays an important role in the Earth's radiative budget. These particles are inherently hygroscopic, that is, they take-up moisture from the air, which affects the extent to which they interact with solar radiation. We demonstrate that the hygroscopic growth of inorganic sea salt is 8-15% lower than pure sodium chloride, most likely due to the presence of hydrates. We observe an increase in hygroscopic growth with decreasing particle size (for particle diameters <150 nm) that is independent of the particle generation method. We vary the hygroscopic growth of the inorganic sea salt within a general circulation model and show that a reduced hygroscopicity leads to a reduction in aerosol-radiation interactions, manifested by a latitudinal-dependent reduction of the aerosol optical depth by up to 15%, while cloud-related parameters are unaffected. We propose that a value of kappa(s) = 1.1 (at RH = 90%) is used to represent the hygroscopicity of inorganic sea salt particles in numerical models.

1 - 16 of 16
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf