EVOLUTION OF THE STRATOSPHERE DURING NORTHERN WINTER 1991 92 AS DIAGNOSED FROM UK-METEOROLOGICAL-OFFICE ANALYSES/

Meteorological analyses, produced at the U.K. Meteorological Office by data assimilation, are used to study the circulation of the stratosph ere in the Northern Hemisphere during winter 1991/92. The analyses are supplemented by Lagrangian visualizations of the circulation. The mai n features discussed are 1) the changes in vertical structure of the c irculation, 2) the merger of anticyclones that precipitated a strong s tratospheric warming, 3) vortex roll up in the upper stratosphere, 4) the entrainment of air into the polar vortex in the middle and upper s tratosphere, and 5) the influence of tropospheric blocking on the lowe r stratosphere. The study provides a meteorological basis for the inte rpretation of data from the Upper Atmosphere Research Satellite.