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| Titel |
Airborne observations of new particle formation events in the boundary layer using a Zeppelin |
| VerfasserIn |
Janne Lampilahti, Hanna E. Manninen, Tuomo Nieminen, Sander Mirme, Iida Pullinen, Taina Yli-Juuti, Siegfried Schobesberger, Juha Kangasluoma, Jenni Kontkanen, Katrianne Lehtipalo, Mikael Ehn, Thomas F. Mentel, Tuukka Petäjä, Markku Kulmala  |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250093103
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| Publikation (Nr.) |
 EGU/EGU2014-7511.pdf |
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| Zusammenfassung |
| Atmospheric new particle formation (NPF) is a frequent and ubiquitous process in the
atmosphere and a major source of newly formed aerosol particles [1]. However, it is still
unclear how the aerosol particle distribution evolves in space and time during an NPF. We
investigated where in the planetary boundary layer does NPF begin and how does the aerosol
number size distribution develop in space and time during it. We measured in Hyytiälä,
southern Finland using ground based and airborne measurements. The measurements were
part of the PEGASOS project.
NPF was studied on six scientific flights during spring 2013 using a Zeppelin NT class
airship. Ground based measurements were simultaneously conducted at SMEAR II
station located in Hyytiälä. The flight profiles over Hyytiälä were flown between
sunrise and noon during the growth of the boundary layer. The profiles over Hyytiälä
covered vertically a distance of 100-1000 meters reaching the mixed layer, stable
(nocturnal) boundary layer and the residual layer. Horizontally the profiles covered
approximately a circular area of four kilometers in diameter. The measurements include
particle number size distribution by Neutral cluster and Air Ion Spectrometer (NAIS),
Differential Mobility Particle Sizer (DMPS) and Particle Size Magnifier (PSM) [2],
meteorological parameters and position (latitude, longitude and altitude) of the
Zeppelin.
Beginning of NPF was determined from an increase in 1.7-3 nm ion concentration.
Height of the mixed layer was estimated from relative humidity measured on-board the
Zeppelin. Particle growth rate during NPF was calculated. Spatial inhomogeneities in particle
number size distribution during NPF were located and the birthplace of the particles was
estimated using the growth rate and trajectories.
We observed a regional NPF event that began simultaneously and evolved uniformly
inside the mixed layer. In the horizontal direction we observed a long and narrow
high concentration plume of growing particles that moved over the measurement
site. The particles of the regional event as well as the particles of the plume were
uniformly distributed in the vertical direction and showed a similar growth rate
of approximately 2 nm/h. The plume caused sharp discontinuities in the number
size distribution of the growing particle mode. These kinds of discontinuities are
seen quite often on SMEAR II data during NPF events and it is likely that they are
caused by inhomogeneous NPF in the horizontal direction (possibly narrow long
plumes).
This work is supported by European Commission under the Framework Programme 7
(FP7-ENV-2010-265148) and by the Academy of Finland Centre of Excellence program
(project no. 1118615). The Zeppelin is accompanied by an international team of scientists
and technicians. They are all warmly acknowledged.
References
[1]Kulmala, M., et al., (2013), Direct Observations of Atmospheric Aerosol
Nucleation, Science, 339, 943-946
[2]Kulmala, M., et al., (2012), Measurement of the nucleation of atmospheric
aerosol particles, Nature Protocols, 7, 1651-1667 |
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