Observation of gravity wave generation and breaking in the lowermost stratosphere

Measurements with the Aberystwyth VHF radar have revealed a striking illust ration of gravity wave generation and breaking in the lowermost stratospher e. Horizontal wind measurements show an inertia-gravity wave that was essen tially monochromatic and persisted for longer than 5 days, with a maximum p erturbation amplitude of approximately 10 ms(-1). Radiosonde measurements s how that this wave induced shear instability that led to intense turbulence close to the tropopause. The event was associated with a highly curved jet stream over Europe, suggesting that geostrophic adjustment was a likely so urce mechanism.