Ambient atmospheric
concentrations of monoterpene compounds were measured above a boreal forest in
Hyytiälä, Finland during 2000–2007. For most of the time, two samples per week
were collected, although there are some gaps in the data due to analytical or
other issues. The monoterpene concentrations reached their maximum in summer,
although they were found to be quite high also during winter. The main compounds
found during winter were [alpha]-pinene, [delta]³-carene,
[beta]-pinene and camphene. In summer 1,8-cineol and sabinene were also present
in the samples. The concentrations of [alpha]-pinene, [beta]-pinene/myrcene,
camphene, [delta]³-carene increased during the measurement period
both in winter and in summer. This increase cannot be explained by
meteorological conditions. The possible explanations could be human activities
in the vicinity of the sampling site in addition to forest growth. The seasonal
cycles of daytime concentrations were found to follow emission fluxes modeled
using a simple temperature dependent parameterisation. The measured monoterpene
concentrations were used, together with emission rate measurements, for
estimating ambient atmospheric [beta]-caryophyllene concentration which cannot
be directly measured due to its high reactivity against
ozone.