EGU General Assembly 2025

Warm weather conditions within the period of the EGU general assembly 2025 allowed for wearing shorts pretty much all day long.

I'm invited to give a solicited talk in the PICO session AS1.33 of "Infrasound, acoustic-gravity waves, and atmospheric dynamics", convener: Alexis Le Pichon, Co-convener: Patrick Hupe, Alain Hauchecorne, Gunter Stober, Sven Peter Näsholm

If you're interested check out my slides and my abstract below.

EGU_20250502_RR_website.pdf

PDF herunterladen • 1.64MB

On the night of 21/22 May 2018, clear-sky conditions enabled a 12-hour-long temperature measurement of the Advanced Mesospheric Temperature Mapper (AMTM) in the mesosphere-lower thermosphere (MLT) region over Río Grande, Argentina. Given a westerly forcing over Patagonia, we observe North-South-oriented phase lines in the AMTM temperature maps exclusively during the westerly phase of the semi-diurnal tide, indicating the deep propagation of mountain waves (MWs) with horizontal wavelengths between 20 km and 40 km. After a wind reversal in the MLT, we observe two large-scale gravity waves (GWs) propagating rapidly in a south-eastward direction. We use one- and two-dimensional wavelet analysis to characterize the observed GWs and find that their wavelengths and phase speeds are consistent with secondary GW theory. Ray tracing results suggest a possible source region for these 2GWs located north-westward, near the Chilean Torres del Paine region. In addition, co-located temperature and wind measurements from the Compact Rayleigh Autonomous Lidar (CORAL) and the Southern Argentine Agile Meteor Radar (SAAMER), in combination with a Monte Carlo approach, allow for the accurate determination of both the GW momentum flux and its uncertainty. Although we exclude a direct cause-and-effect relationship within our field of view, we find that, on average, the observed MWs carry momentum fluxes an order of magnitude larger than those of the 2GWs.

Photo taken by Neil Hindley. Thanks Neil :)