Transport of water vapour in a stratosphere-troposphere general circulation model. II: Trajectories

Trajectories have been computed during a 10-day period in January for approximately zonal rings of parcels in the upper troposphere and lower stratosphere of a general circulation model. Time histories of ozone and water vapour highlight the central role of the subtropical jet streams as mixing agents for tropospheric and stratospheric air. There is some evidence of inertial oscillations in the upper tropical troposphere, particularly at longitudes where there is no large-scale convergence or divergence. The western tropical Pacific from about 150°E to 160°W appeared to be a centre of large-scale motion, with pronounced upper tropospheric descent below about 10 km and ascent at and above 16 km, apparently linked to large-scale ascent in the middle and high latitude stratosphere up to 30 km.