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2.2. STRATOSPHERIC OZONE 39
2.2.2 Stratospheric photochemistry of ozone, nitrogen and chlorine species
Participating scientists at IUP Heidelberg Butz, A., M. Dorf, F. Weidner, and K. Pfeilsticker
Abstract In the recent past the LPMA/DOAS balloon payload has conducted several stratospheric
balloon flights at various locations and in different seasons. The inferred abundances of stratospheric
ozone (O3) and nitrogen dioxide (NO2) are checked for internal consistency and compared to correlative
data measured by the satellite borne instrument SCIAMACHY.
Figure 2.15: Relative deviations between satellite (retrieved by IUP Bremen) and balloon borne measurements
of O3 (left panel) and NO2 (right panel) vertical profiles. Observation sites and conditions are indicated in the
legend. The mean deviation of all coincident data in the 20 km – 31 km altitude is 4.3% with 10.8% standard
deviation for O3 and 1.8% with 12.4% standard deviation for NO2. The grey lines indicate the mean and the
one and two times standard deviation boundaries with respect to the 20 km – 31 km altitude range. Note the
broken abscissa.
Background Nitrogen oxides dominate the catalytic
destruction of stratospheric O3 between 25
and 40 km altitude. Thus, NO2 and O3 measurements
are of primary importance to study
stratospheric photochemistry. Recent studies indicate
that for selected geophysical conditions the
agreement between measured and modeled O3 and
NO2 is better than 10%. Accordingly, measurements
of high accuracy are required to constrain
or to be compared with photochemical models.
Our study aims at estimating the accuracy of
state-of-the-art remote sensing measurements of
O3 and NO2.
Funding The present work has been supported
by ESA, BMBF, DLR and the European Union.
Methods and results Abundances of stratospheric
O3 and NO2 inferred from traditional
solar occultation measurements of the
LPMA/DOAS balloon payload are checked for internal
consistency and subsequently compared to
collocated observations of the SCanning Imaging
Absorption spectroMeter for Atmospheric CHartographY
(SCIAMACHY) onboard the European
Envisat satellite. Our comparison scheme accounts
for the temporal and spatial mismatch (airmass
trajectory modell) as well as for the differing
photochemical conditions (1D chemistry modell)
between the balloon and the satellite borne observations.
The internal agreement of the balloon borne
measurements is 10% and 20% for O3 and NO2,
respectively. Typical deviations between SCIA-
MACHY and the balloon borne data amount to
20% for both gases in the 20 to 30 km altitude
range, see figure (2.15). Below 20 km the agreement
worsens mainly due to lower sensitivity of
the satellite retrieval.
Outlook/Future work
• Extension of the O3 and NO2 validation
study to tropical latitudes
• Case studies of the stratospheric nitrogen
and chlorine budget/partitioning and implications
for ozone loss
• Abundance of iodine radicals in the tropical
upper troposphere and stratosphere
Main publication Butz, A. et al., Intercomparison
of Stratospheric O3 and NO2 abundances
retrieved from balloon borne direct sun observations
and Envisat/SCIAMACHY limb measurements,
Atmos. Chem. Phys. Disc. 5, 10747–
10797, 2005.