Carbon monoxide (CO) and water vapor (H2O) act as good dynamics tracers in the middle atmosphere. Analyzing Aura Microwave Limb Sounder (MLS) CO and H2O measurements, we obtained more complete characterization of the coupled dynamics between 316 hPa (∼ 9 km) and 0.002 hPa (∼ 90 km) in terms of the northern annular mode (NAM) in the Northern Hemisphere (NH) winters and the southern annular mode (SAM) in the Southern Hemisphere (SH) winters. We are able to evaluate the vertical descent rate of the polar vortex in NH and SH winters from the NAM and SAM evolution, as well as interplays among NAM, planetary and gravity waves.II. Gravity wave properties and propagation observed by MLS and AIRS
Microwave Limb Sounder (MLS) and Atmosphere Infrared Souder (AIRS) radiances are used to infer the temperature fluctuations induced gravity waves (GWs). The two instruments have different sensitivities to wave scales with λz/λh ∼ 0.1 and λz/λh ∼ 1 for MLS and AIRS, respectively. Because of smearing effects by the instrument field-of-view, we sort variance measurements according to the viewing angle to obtain preferred wave propagation in the meridional direction from MLS and in the zonal direction from AIRS. With careful handling of instrument measurement noise, these small wave variances reveal valuable information on global GW distribution and propagation.