Analysis of gravity waves during the POLINAT experiment and some consequences for stratosphere-troposphere exchange

Measurements of horizontal wind speed and direction obtained during the Pollution from Aircraft Emissions in the North Atlantic Flight Corridor experiment are used to identify some waves propagating near the tropopause level. The variation observed simultaneously in the ozone and water vapor distribution allows the signature and different characteristics of the waves to be identified. With the help of the analysis of European Centre for Medium-Range Weather Forecasts the conditions for generation of different kinds of waves are reviewed. It is shown that some of the characteristics of the observed waves are a consequence of nonlinear wave-wave interaction. The irregularity of the tropopause height in the region suggests that the propagating waves can be a mechanism for cross-tropopause mixing.