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This study uses data from the Upper Atmosphere Research Satellite (L'ARS) to investigate two topics in middle atmosphere dynamics: the ••4-day wave" and transport processes deduced from atmospheric carbon monoxide. The 4-day wave is an eastward moving quasi-nondispersive feature with 4 day period occurring near the winter polar stratopause. Evidence of the 4day feature is presented in UARS Microwave Limb Sounder (MLS) temperature, geopotential height, quasigeostrophic potential vorticity (PV). and ozone from the late southern winters of 199^2 and 1993. Space-time spectral analyses reveal a double-peaked vertical temperature structure with an out-of-phase relationship between the two peaks. The height variation of the 4-day ozone signal compares well with a linear advective-photochemical tracer model. Regions of negative PV gradient and positive Eliassen-Palm flu.K divergence are shown to occur, con­ sistent with instability dynamics playing a role in w'ave forcing. The three-dimensional wave structure resembles the PV "•charge" concept, wherein a PV anomaly in the atmosphere (anal­ ogous to an electrical charge in a dielectric material) induces a geopotential Field, a vertically oriented temperature dipole. and circulation about the vertical a.xis. Observations of carbon monoxide in the upper stratosphere and lower mesosphere from the U.ARS Improved Stratospheric and \[esospheric Sounder (ISAMS) are presented during the early northern winter I991/199"2. High CO mixing ratios are found to saturate the polar vortex. 2D analyses in the meridional plane indicate: (I) Increasing mixing ratio with altitude. (2) Large mixing ratios near the Arctic winter pole due to downward advection from the diabatic circulation. (3) -A. tropical upper stratosphere ma.ximum likely due largely to methane oxidation. IS.A.MS CO data are compared with CO output from a 3D chemistry and transport model (CTM), initialized with ISAMS CO. ISAMS and CTM horizontal distributions compare

Dynamical processes in the middle atmosphere as observed from Upper Atmosphere Research Satellite limb-sounding data