We report the results of a recent study to examine possible causal factors that could explain the observed differences in PMSE intensity in the northern and southern hemispheres. A variety of satellite data, models and ground‐based radar observations in the two hemispheres during local summer have been examined in this attempt. We will show results of inter‐hemispheric comparisons of temperatures, winds, and water vapor. The primary conclusions that can be drawn from these studies are that, while water vapor differences in the two hemispheres are difficult to interpret at near‐mesopause altitudes, the inter‐hemispheric temperature comparisons show clearly that the southern hemispheric mesopause is indeed a few degrees warmer. Moreover, southern summer mesospheric mean winds are considerably weaker than they are in the north. These results provide support for earlier speculations ...

Vertical velocity measurements of atmospheric winds are becoming increasingly important. To obtain the long-term mean vertical motion of the atmosphere is difficult to do, both because of the small velocities involved and because of the finite width of the antenna beam. Since the vertical wind measurement is very sensitive to the tilt of the vertically-directed antenna beam, we decided to get the Jicamarca beam direction by measuring the phase and amplitude of a ref­erence signal at each of the antenna feed points. Our results tell us that, while the antenna pointing direction is already good, there is room for improvement.