Gravity waves contribute significantly to atmospheric dynamics. Usually, in general circulation models and chemistry climate models the effect of gravity waves on the background flow has to be parametrized. A key quantity of these parametrization schemes is the vertical flux of horizontal momentum due to gravity waves.

Gravity wave parametrization schemes are poorly constrained, and for a further improvement global observations of gravity wave momentum fluxes from satellite are required. First attempts were based on absolute values of gravity wave momentum fluxes derived from satellite instruments having only one viewing direction. For a better comparison with parametrization schemes, however, directional momentum fluxes are needed.

We make use of 3D temperature distributions resulting from a dedicated high resolution temperature retrieval based on the 3D observations of the nadir scanning satellite instrument AIRS on board the EOS Aqua satellite. Full 3D gravity wave wavenumber vectors are determined in small 3D fitting volumes, and global distributions of zonal and meridional gravity wave momentum fluxes are derived. Resulting global patterns of momentum fluxes in the stratosphere are similar to those previously known from absolute momentum fluxes: enhanced values are found in the polar jets and in the summertime subtropics. Momentum fluxes derived from AIRS are directed prevalently opposite to the background winds, i.e. eastward in the summertime subtropics, and prevalently westward in the polar jets. In addition, in the polar jets meridional momentum fluxes are opposite in their direction to the meridional winds induced by planetary waves.

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*email: m.ern@fz-juelich.de
*Preference: Oral