5th Swiss Geoscience Meeting, Geneva 2007
Interannual-to-decadal Variability of Stratospheric
Chemistry and Climate during the 20th Century
Fischer Andreas*, Brönnimann Stefan*, Rozanov Eugene*,**
*Institute for Atmospheric and Climate Science, Universitätsstrasse 16, ETH Zürich,
CH-8092 Zürich (andreas.fischer@env.ethz.ch)
**PMOD/WRC, Dorfstrasse 33, CH-7260 Davos Dorf
Stratospheric interannual-to-decadal variability is dominated to a large degree
by external forcings, such as variability of the sun, volcanic eruptions, as well as
by internal factors like El Niño Southern Oscillation (ENSO) variability and the
quasi-biennial oscillation (QBO). The current data records as well as model
simulations addressing stratospheric chemical climate variability mostly cover
the past few decades only, which often is not sufficient to address interannualto-decadal variability.
Here we present results of transient simulations with the chemistry-climate
model (CCM) SOCOL, spanning the whole 20th century. SOCOL is a
combination of the middle atmosphere version of ECHAM4 (MPI, Hamburg) and
the chemistry-transport model MEZON (PMOD/WRC, Davos). The simulations
are carried out in ensemble-mode (9 members) prescribing sea surface
temperature, sea ice distribution, volcanic aerosols, solar variability,
greenhouse gases, ozone depleting substances, land surface changes, and
QBO.
We will present an extensive validation of model results against various
observational and (prior to 1957) reconstructed upper-air datasets as well as
several long total ozone series (Oxford starting in 1924, Arosa in 1926, Tromso
in 1935, and Spitsbergen in 1950).
Results on the effect of solar and volcanic forcings as well as on the effect of
ENSO on the stratosphere will be presented.
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