Joint Seminar: Iodine monoxide above Antarctica – 4 years of satellite observations

Research over the past years has revealed the importance of iodine for
tropospheric composition. In the reaction with ozone, atomic iodine
radicals form iodine monoxide (IO) thereby destroying the ozone.
Starting with IO, higher iodine oxides can form, which may lead to the
formation of fine new particles possibly growing to condensation nuclei.

In several locations, IO and other iodine species were observed by means
of ground-based instrumentation with amounts in the range of several
pptv. With the development of sensitive satellite sensors, it is now
possible to retrieve atmospheric IO columns from space. This provides
the opportunity to observe IO on a more global scale. Due to low
abundances and the high temporal and spatial variation of the reactive
iodine species, the detection limit of the satellite analysis lies close
to the expected IO amounts. As a higher surface spectral reflectance
leads to a better signal-to-noise ratio and to an enhanced sensitivity
towards the ground layers, where most of the IO is situated, the best
detection limit for IO is achieved in the Antarctic region.

In this talk, IO detection using the SCIAMACHY sensor will be discussed
and the results of several years of satellite observations will be
shown. A seasonal cycle of IO around Antarctica is revealed, which is
repeated in every year and compares well to the few existing
ground-based measurements. In parts, the observations can be understood
by current knowledge of release processes and chemical reaction
pathways. To some extent, the observations remain unexplained and ask
for more observational confirmation as well as modelling support and
discussion.

Date

29.04.2008

Time

15:15 h

Place

Bundesstr. 53, room 022/023
Seminar Room 022/023, Ground Floor, Bundesstrasse 53, 20146 Hamburg, Hamburg

Speaker

Anja Schönhardt, Institut für Umweltphysik, Universität Bremen

Organizers


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