Coincident measurements of ground-based lidar and the AWE OH imager onboard the ISS above the Southern Andes

Kurzfassung

Ground-based lidar measurements with the CORAL instrument at the southern tip of South America (53.8S, 67.8E) provide vertical temperature measurements and gravity wave characteristics at a resolution of 15 min throughout the middle atmosphere, up to the OH emission layer. Of this layer, the AWE instruments onboard the International Space Station provides global imaging of OH brightness and temperature at 2 km x 2 km resolution. We identified coincident and common-volume observations during winter 2024 and analyze these for gravity wave and instability dynamics. The geographic region is known for strong orographic wave forcing and deep propagation of gravity waves into the middle atmosphere during winter, including mountain wave breaking, secondary wave generation, and the generation of vortex rings and Kelvin-Helmholtz instabilities in the upper mesosphere. Gravity waves identified by lidar are typically 2-3 hours in period and 10-15 km in vertical wavelength in the upper stratosphere, lower mesosphere. In the upper mesosphere, smaller scales prevail. By wavelet analysis, we find that periods down to 40 min sporadically occur in thin, confined altitude layers. These observations are combined with AWE measurements showing varied local responses including mesospheric bores, small-scale mountain waves and large- and small-scale vortex rings and ring clusters related to the breaking of the gravity waves propagating from below.