| 2. |
- Junninen, Heikki, et al.
(författare)
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Terpene emissions from boreal wetlands can initiate stronger atmospheric new particle formation than boreal forests
- 2022
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Ingår i: Communications Earth and Environment. - : Springer Science and Business Media LLC. - 2662-4435. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- Aerosols and their interaction with clouds constitute the largest uncertainty in estimating the radiative forcing affecting the climate system. Secondary aerosol formation is responsible for a large fraction of the cloud condensation nuclei in the global atmosphere. Wetlands are important to the budgets of methane and carbon dioxide, but the potential role of wetlands in aerosol formation has not been investigated. Here we use direct atmospheric sampling at the Siikaneva wetland in Finland to investigate the emission of methane and volatile organic compounds, and subsequently formed atmospheric clusters and aerosols. We find that terpenes initiate stronger atmospheric new particle formation than is typically observed over boreal forests and that, in addition to large emissions of methane which cause a warming effect, wetlands also have a cooling effect through emissions of these terpenes. We suggest that new wetlands produced by melting permafrost need to be taken into consideration as sources of secondary aerosol particles when estimating the role of increasing wetland extent in future climate change.
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| 3. |
- Lampilahti, Janne, et al.
(författare)
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Zeppelin-led study on the onset of new particle formation in the planetary boundary layer
- 2021
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Ingår i: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 21:16, s. 12649-12663
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Tidskriftsartikel (refereegranskat)abstract
- We compared observations of aerosol particle formation and growth in different parts of the planetary boundary layer at two different environments that have frequent new particle formation (NPF) events. In summer 2012 we had a campaign in Po Valley, Italy (urban background), and in spring 2013 a similar campaign took place in Hyytiälä, Finland (rural background). Our study consists of three case studies of airborne and ground-based measurements of ion and particle size distribution from ∼1 nm. The airborne measurements were performed using a Zeppelin inside the boundary layer up to 1000 m altitude. Our observations show the onset of regional NPF and the subsequent growth of the aerosol particles happening almost uniformly inside the mixed layer (ML) in both locations. However, in Hyytiälä we noticed local enhancement in the intensity of NPF caused by mesoscale boundary layer (BL) dynamics. Additionally, our observations indicate that in Hyytiälä NPF was probably also taking place above the ML. In Po Valley we observed NPF that was limited to a specific air mass.
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| 4. |
- Schobesberger, Siegfried, et al.
(författare)
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Airborne measurements over the boreal forest of southern Finland during new particle formation events in 2009 and 2010
- 2013
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Ingår i: Boreal environment research. - 1239-6095 .- 1797-2469. ; 18:2, s. 145-163
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Tidskriftsartikel (refereegranskat)abstract
- Schobesberger, S., Vaananen, R., Leino, K., Virkkula, A., Backman, J., Pohja, T., Siivola, E., Franchin, A., Mikkila, J., Paramonov, M., Aalto, P.P., Krejci, R., Petaja, T. & Kulmala, M. 2013: Airborne measurements over the boreal forest of southern Finland during new particle formation events in 2009 and 2010. Boreal Env. Res. 18: 145-163. We conducted airborne observations of aerosol physical properties over the southern Finland boreal forest environment. The aim was to investigate the lower tropospheric aerosol (up to 4-km altitude) over an area of 250 by 200 km, in particular during new particle formation (NPF) events, and to address the spatial variability of aerosol number concentration and number size distribution. The regional NPF events, detected both airborne and at the ground, with air masses originating from the Arctic or northern Atlantic Ocean were studied throughout the boundary layer and throughout the area covered. Three suitable case studies are presented in more detail. In two of these studies, the concentrations of nucleation mode particles (3-10 nm in diameter) were found considerably higher (up to a factor of 30) in the upper parts of the planetary boundary layer compared to ground-based measurements during the nucleation events. The observed vertical variation can be connected to boundary layer dynamics and interactions between the boundary layer and the lower free troposphere, likely yielding high concentrations of newly formed aerosol particles. Our results suggest that nucleation does not necessarily occur close to the surface. In one presented case we found evidence of NPF occurring in a limited area above cloud, in the complete absence of a regional NPF event.
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