G. Wooldridge et al., OZONE CONCENTRATION CHARACTERISTICS AT A HIGH-ELEVATION FOREST SITE, Theoretical and applied climatology, 56(3-4), 1997, pp. 153-164
Atmospheric ozone concentrations have been monitored at a subalpine fo
rest ecosystem site, 3180 m above mean sea level (msl), and at a 2680
m msl forest-steppe ecotone site 15 km to the southeast. Ozone concent
rations were monitored at three heights above the ground on a 30 m tow
er al the higher elevation site, and on a 10 m tower in a large meadow
downwind of this site. The research reported here concentrates on the
data for the first six months of 1990-1994. The diel amplitude of ozo
ne concentrations is very small in winter, increasing as the seasons a
dvance to June. Following snowmelt in late May or June. the nighttime
minima decrease under the forest canopy. The highest monthly mean ozon
e concentrations occur in April or May, depending on the year. Episoda
l high concentrations were recorded during spring months when upper le
vel atmospheric low pressure troughs and cut-off low centers occurred.
These contributions peak in May, and add about 10% to normal May back
ground ozone concentrations. varying widely from year to year. Spectra
l representations of ozone concentrations, illustrate the suppression
of the diel peak during spring months, when stratospheric-tropospheric
intrusion patterns show no significant diel cycle.