Toward direct measurement of atmospheric nucleation.
Atmospheric aerosol formation is known to occur almost all over the world, and the importance of these particles to climate and air quality has been recognized. Although almost all of the processes driving aerosol formation take place below a particle diameter of 3 nanometers, observations cover only larger particles. We introduce an instrumental setup to measure atmospheric concentrations of both neutral and charged nanometer-sized clusters. By applying the instruments in the field, we come to three important conclusions: (i) A pool of numerous neutral clusters in the sub-3 nanometer size range is continuously present; (ii) the processes initiating atmospheric aerosol formation start from particle sizes of approximately 1.5 nanometers; and (iii) neutral nucleation dominates over the ion-induced mechanism, at least in boreal forest conditions.
Kulmala
Markku
M
Department of Physical Sciences, University of Helsinki, Post Office Box 64, FI-00014, Helsinki, Finland. kulmala@pcu.helsinki.fi
Riipinen
Ilona
I
Sipilä
Mikko
M
Manninen
Hanna E
HE
Petäjä
Tuukka
T
Junninen
Heikki
H
Maso
Miikka Dal
MD
Mordas
Genrik
G
Mirme
Aadu
A
Vana
Marko
M
Hirsikko
Anne
A
Laakso
Lauri
L
Harrison
Roy M
RM
Hanson
Ian
I
Leung
Carl
C
Lehtinen
Kari E J
KE
Kerminen
Veli-Matti
VM