G. Stiller, T. von Clarmann, F. Haenel, E. Eckert, B. Funke,
N. Glatthor, U. Grabowski, S. Kellmann, M. Kiefer, A. Linden,
S. Lossow, and M. Lopez-Puertas
Global stratospheric mean age of air and its temporal variation
from MIPAS SF6 observations
The first global stratospheric mean age of air observational data record
covering almost 10 years has been derived from monthly zonal means of
SF6 measured by MIPAS/Envisat. The 10-years time series of global
stratospheric age of air has been analysed regarding its short-term
variations (seasonal, semi-annual, QBO), and its decadal behaviour.
The derived linear trends were found to be inhomogeneous over the globe,
with increasing age of air in Northern mid-latitudes and middle tropics,
and decreasing age of air in the tropical lowermost stratosphere and
larger parts of the Southern mid-latitudes. The trend pattern will be
compared to that of other transport tracers measured by MIPAS.
Analysis of the amplitudes and phases of the seasonal variation allows
conclusions on the coupling of stratospheric regions to each other.
The observational data will be interpreted in terms of a
accelaration/decelaration of the Brewer-Dobson circulation and
discussed in context with recent published modelling results.
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