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Ten-Year SCIAMACHY Stratospheric
Aerosol Data Record: Signature
of the Secondary Meridional Circulation
Associated with the Quasi-Biennial
Oscillation
Lena A. Brinkhoff, Alexei Rozanov, Ren
Hommel,
Christian von Savigny, Florian Ernst, Heinrich Bovensmann
and John P. Burrows
é
Abstract The ten-year long stratospheric aerosol data record, retrieved from
SCIAMACHY limb scattered sunlight measurements, is a continuous data set
during the period from 2002 to 2012. As a result of the relatively high vertical
resolution (3
4 km) and near global coverage on the sun-facing side of the Earth,
the retrieved data set (V1.1) provides global information about the variability of
stratospheric aerosol extinction between the tropopause and about 33 km altitude.
Stratospheric aerosols are near-spherical droplets mainly comprised of sulfuric acid
and water. The background aerosol load in the stratosphere results from the tropical
injection of tropospheric air containing precursors of stratospheric aerosols. A
sporadic but important source is the injection of gases from volcanic eruptions.
These release the precursor gas SO
2
into the troposphere or even directly into the
stratosphere due to convection induced by volcanic heat. Stratospheric aerosols
belong to the essential climate variables, as they in
-
s radiation
budget and are involved in the depletion of ozone. In this study, we analyse the time
series of SCIAMACHY observed tropical aerosol extinction coef
fl
uence the Earth
'
cients at 30 km
altitude. A distinct biennial variation has been found. Based on ECMWF ERA-
Interim reanalysis data, this variation is explained by the secondary meridional
circulation that is induced by the quasi-biennial oscillation of the tropical zonal
wind in the stratosphere.
Keywords Stratospheric aerosols
Tropical stratosphere
QBO
Secondary
meridional circulation
SCIAMACHY
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