Seasonal vertical coupling of gravity waves over the Southern Andes from 3D satellite and high-resolution lidar observations

In the mesosphere, vertical wind velocities can exceed tens of m/s, driven by gravity wave (GW) processes such as wave breaking and the generation of secondary GWs. These dynamic events play a crucial role in redistributing energy and momentum across atmospheric layers. In this study, we investigate the GW dynamics over the Southern Andes—a prominent hotspot for GW activity—using a combination of satellite and ground-based observations. In particular, we analyze nearly two decades of atmospheric infrared sounder (AIRS) data, along with approximately 5 years of sodium (Na) lidar observations from the Andes Lidar Observatory (ALO). Our analysis reveals a clear seasonal co-variation between lower-stratospheric GW activity and mesospheric perturbations, with both datasets exhibiting pronounced austral-winter enhancements. The mesospheric Na-lidar variance also exhibits secondary maxima during late summer and spring; a simple vertical-wavenumber spectral analysis indicates that these shoulder enhancements result from modest, broadband increases in short-vertical-wavelength power. This variability is consistent with vertical coupling mediated by seasonally varying background winds and mesospheric wave dissipation.