In-situ meteorological observations collected during long-duration balloon flights in the lower stratosphere provide unique information to study gravity waves over wide geographical areas. One important characteristic of these flights is that the balloons are advected by the wind, so that observations directly provide the gravity-wave intrinsic frequencies. During balloon flights performed in 2010 both in the tropics (Pre-Concordiasi) and in the Southern Hemisphere polar vortex (Concordiasi), meteorological measurements were performed every 30 s, which enables us to virtually resolve the whole gravity-wave spectrum. Methods recently updated to analyze this high-resolution dataset give access to the full wave characteristics (direction of propagation, horizontal and vertical wavelengths, phase speeds, etc) The balloon observations are in particular used to report on the vertical fluxes of horizontal momentum carried by gravity waves, which allows us to identify the major sources of wave activity in the sampled regions. The momentum fluxes probability distribution functions are furthermore used to describe wave intermittency. Phase-speed spectrum of momentum fluxes, which partly controls where wave break in the atmosphere, will be presented. They exhibit strong anisotropy already in the lower stratosphere. Last, momentum-flux and energy distributions in the wavenumber/frequency space will be contrasted: they notably highlight the role of high-frequency waves in forcing the middle atmosphere circulation.

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*email: albert.hertzog@lmd.polytechnique.fr
*Preference: Invited