Chemistry Reference
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Fig. 9 Typical ranges of Aitken and accumulation mode number concentrations (separated by
100 nm dry diameter) in different European environments. The areas show the densest parts of the
different environment concentration scatter (see Asmi et al. [
18
] for details, adapted from the same
article)
sign that the two modes are relatively non-correlated in these air masses. In the case
of Atlantic and polluted Italian background, the two modes are correlated, but not in
diagonal direction. Atlantic air masses seem to increase in concentration mostly in
Aitken mode, suggesting that most of the variability is in sub-100 nm range. The
polluted background environments instead have a strong increase in accumulation
mode, with relatively low variability in Aitken mode. Only Arctic haze environ-
ment has very strong dominance of the accumulation mode, although considerable
parts of most other environments sometimes show such behavior.
Overall, in most environments the two modes are correlated, but different
environments have very varying concentration levels of the two modes (see
Table
1
), and their relationship varies strongly from environment to environment
and has relatively large scatter.
