The NATO Advanced Research Workshop on "Dynamics, Transport am. Photochemistry in the Middle Atmosphere of the Southern Hemisphere" was held in San Francisco, California, U.S.A., 15-17 April 1989. In addition to NATO, the workshop was supported by the University of California, Los Angeles, and by the National Aeronautics and Space Administration, U.S.A. (NASA). The American Meteorological Society was a co-operating organization. The venue for the workshop was the Lone Mountain Conference Center of the University of San Francisco. The workshop was organized and directed by Dr A.O'Neill (Hadley Centre for Climate Prediction and Research, Meteorological Office, Bracknell, U.K.) and Prof C.R. Mechoso (Dept of Atmospheric Sciences, University of California, Los Angeles, U.S.A.). The workshop was the third one held as part of the Middle Atmosphere in the Southern Hemisphere (MASH) project, an international effort (under the auspices of the Middle Atmosphere Program) to learn more about dynamics, transport and photochemistry in the middle atmosphere of the southern hemisphere. Before the discovery that, during recent years, a dramatic thinning of the ozone layer takes place over Antarctica in spring - the "ozone hole" - the middle atmosphere of the southern hemisphere had received much less attention than that of the northern hemisphere from meteorologists and atmospheric chemists. The MASH project was instituted to remedy this comparative lack of interest.

Middle atmosphere dynamics and transport: some current challenges to our understanding.- On data sources and quality for the southern hemisphere stratosphere.- The seasonal evolution of the extra-tropical stratosphere in the southern and northern hemispheres: systematic changes in potential vorticity and non-conservative effects of radiation.- The final warming of the statosphere.- Comparison of the Southern Hemisphere springs of 1988 and 1987.- A comparison of the dynamic life cycles of tropospheric medium-scale waves and stratospheric planetary waves.- Traveling planetary waves in the middle atmosphere.- Dynamical properties of the Antarctic circumpolar vortex inferred from aircraft observations.- Large stratospheric sudden warming in Antarctic late winter and shallow ozone hole in 1988: observation by Japanese Antarctic research expedition.- A possible influence of sea surface temperature variation on the recent development of ozone hole.- Gravity Waves in the Southern Hemisphere Middle Atmosphere: A Review of Observations.- Gravity waves in the middle atmosphere of the southern hemisphere.- Nitrogen chemistry in Antarctica: a brief review.- The potential role of HOx and C10x interactions in ozone hole photochemistry.- Ozone transport in the southern hemisphere.- Future observations of the middle atmosphere.- Modelling and observations: The use of diagnostics.- Antarctic ozone depletion and potential effects on the global ozone budget.- Alphabetical index of authors.