M. Vanroozendael et al., GROUND-BASED OBSERVATIONS OF STRATOSPHERIC NO2 AT HIGH AND MIDLATITUDES IN EUROPE AFTER THE MOUNT-PINATUBO ERUPTION, JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, 102(D15), 1997, pp. 19171-19176
Nitrogen dioxide has been monitored at the International Scientific St
ation at the Jungfraujoch (46 degrees N, 8 degrees E) since June 1990
and at Sodankyla (67 degrees N, 27 degrees E) since January 1990. NO2
vertical column abundances are measured during the morning and evening
twilights by application of the differential absorption method using
the sunlight scattered at zenith in the visible range. The available t
ime series shows a significant reduction of NO2 starting in winter 199
2, after the eruption of the Mount Pinatubo volcano. A maximum decreas
e of about 35% is observed in January 1992 at both stations. The conti
nued series of observations shows the recovery of the NO2 column until
August 1995. These results are compared with two-dimensional chemical
model calculations, including the effect of heterogeneous reactions o
n observed Pinatubo aerosols. In general, the modeled NO2 columns agre
e qualitatively with the observations although the amplitude of the se
asonal variation is underestimated, possibly due to internal limitatio
ns of the model which, for example, does not include diurnal changes.
The observed and calculated NO2 percent changes are in good agreement,
which confirms quantitatively the impact of the heterogeneous chemist
ry on stratospheric NO2.