Mesopause temperatures and relative densities at midlatitudes observed by the Mengcheng meteor radar

The atmospheric temperatures and densities in the mesosphere and lower thermosphere (MLT) region are essential for studying the dynamics and climate in the middle and upper atmosphere. In this study, more than 9 years of mesopause temperatures and relative densities estimated by using ambipolar diffusion coefficient measurements observed by the Mengcheng meteor radar (33.4°N, 116.5°E) are presented. The intercomparison between the meteor radar and Thermosphere Ionosphere Mesosphere Energetics and Dynamics/Sounding of the Atmosphere by Broadband Emission Radiometry (TIMED/SABER) and EOS Aura/Microwave Limb Sounder (MLS) observations indicates that the meteor radar temperatures and densities agree well with the simultaneous satellite measurements. The annual variations dominate mesopause temperatures, with a maximum during winter and a minimum during summer. The mesopause relative densities also show annual variations with strong maxima near the spring equinox and weak maxima before the winter solstices and with a minimum during summer. In addition, the mesopause density exhibits a structure similar to that of the zonal wind; as the zonal wind flow is eastward (westward), the mesopause density decreases (increases). At the same time, the meridional wind shows a structure similar to that of the mesopause temperature; as the meridional wind shows northward (southward) enhancements, the mesopause temperature increases (decreases). Simultaneous horizontal wind, temperature, and density observations provide multiple mesospheric parameters for investigating mesospheric dynamics and thermodynamic processes and have the potential to improve widely used empirical atmospheric models.