The NATO Advanced Research Workshop on "Transport Processes in the Middle Atmosphere" was held in Erice, Sicily, from November 23 through November 27, 1986. In addition to NATO, the workshop was supported by the International School of Atmospheric Physics of the Ettore Majorana Center for Scientific Culture, and by the National Research Council of Italy. The Organizing Committee was fortunate to enlist the participation of many of the experts in the field, and this book is an account of their contributions. In order to expedite publication and keep the results "as fresh as possible" , it was decided to forego formal review of the papers; instead, the authors were asked to solicit internal reviews from their colleagues. Further, each paper was thoroughly discussed and criticized during the meeting, and those discussions have been taken into account in the preparation of the final version of the manuscripts. Occasional short presentations were made by some of the Workshop participants who wished to provide information complementary to that given in the invited talks. These presentations are not included in this book, which contains only the invited papers. The book is organized into five chapters corresponding to the different topics cov­ ered by the Workshop. The first two chapters contain general reviews of the dynamical climatology of the middle atmosphere and of the growing body of data available on the dis­ tribution of chemical constituents.

1. Dynamical Climatology of the Middle Atmosphere.- Troposphere-stratosphere general circulation statistics.- A review of observations of the quasi-biennial and semiannual oscillations of wind and temperature in the tropical middle atmosphere.- Recent progress in gravity wave saturation studies.- Radar observations of gravity waves in the mesosphere.- The seasonal evolution of the stratosphere in the northern hemisphere.- 2. Observations and Analysis of Chemical Constituents.- Distributions of ozone and nitric acid measured by the Limb Infrared Monitor of the Stratosphere (LIMS).- The near global distributions of middle atmospheric H2O and NO2 measured by the NIMBUS 7 LIMS experiment.- Satellite measurements of stratospheric aerosols.- Evidence for planetary wave breaking from satellite data: The relative roles of diabatic effects and irreversible mixing.- Seasonal variation in the variance of stratospheric ozone and potential temperature over hohenpeissenberg, F.R.G..- Satellite observations of the antarctic ozone depletion.- 3. Transport in the Middle Atmosphere: Theory and Modeling.- Transport mechanisms in the middle atmosphere: anintroductory survey.- A coupled model of zonally averaged dynamics, radiation and chemistry.- The influence of the semi-annual and quasi-biennial oscillations on equatorial tracer distributions.- The effect of breaking gravity waves on the distribution of trace species in the middle atmosphere.- Modeling the transport of chemically active constituents in the stratosphere.- Comprehensive modeling of the middle atmosphere: The influence of horizontal resolution.- Dynamics and tracer transport in the middle atmosphere: an overview of some recent developments.- Evidence of planetary wave breaking in the stratosphere using a photochemical modelalong air parcel trajectories.- The production of temporal variability in trace constituents concentrations.- Parcel dispersion in stratospheric models.- Diffusion coefficients calculated from satellite data.- Vacillations induced by interference of stationary and traveling planetary waves.- 4. Radiative Processes and Transport.- Response of the middle atmosphere to changing O3 and CO2-A speculative tutorial.- The residual circulation: Interhemispheric differences and heating and eddy components.- Analysis of the mean meridional circulation using satellite data.- 5. Observational Techniques.- Irregular and diurnal variability in asynoptic measurements of stratospheric trace species.- Contribution of radar observations of winds, waves, turbulence and composition to study transport processes in the middle atmosphere.- Lidar sounding of the structure and dynamics of the middle atmosphere: a review of recent results relevant to transport processes.- Alphabetical Index of the Authors.