A. Gabriel
Validation of global wind fields and circulation patterns in the upper
stratosphere and lower mesosphere based on Aura/MLS satellite data
The limitations in the global coverage and maximum altitudes (>>30km) of wind
measurements by standard radiosondes might lead to large uncertainties in
the upper stratospheric and lower mesospheric wind fields produced by the
assimilation models, and to significant differences between different
reanalysis data sets for altitudes above >>30km. In the framework of a
current project daily-mean global wind fields for both the stratosphere and
mesosphere are derived from Aura/MLS satellite data, i.e., from observed
temperature profiles via standard balanced equations and by an optimization
of the balanced wind fields via an inversion calculation of the tracer
transport, where the observed day-to-day variations of O3 and H2O are used
as input. The results are verified based on local wind profiles derived from
Lidar and Radar measurements. The resulting data set will provide an
important new tool for validating upper stratospheric and mesospheric wind
fields.
In particular, we currently analyse the three-dimensional (3D) residual
circulation, as a meaningful proxy for the 3D Brewer-Dobson circulation (3D
BDC), based on ECMWF reanalysis data, model calculations and Aura/MLS data.
First results indicate a pronounced effect of the Quasibiennal Oscillation
(QBO) on the longitudinal structure of the vertical residual wind and tracer
transport at northern mid-latitudes during winter (i.e., wave-1 structure
during QBO-East, wave-2 structure during QBO-West), and a change in the
distribution of high and low anomalies in geopotential height at surface
pressure level due to the OBO-induced change in the stratospheric mass
distribution (i.e., a change towards negative phase of North-Atlantic
Oscillation). In summary, the ongoing project works could contribute to the
S-RIP Final Report by providing a validation of the global wind fields and
3D residual circulation patterns in the upper stratosphere and lower
mesosphere, as well as an analysis of their influence on the long-term
variability of trace gas distributions and regional climate conditions.
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