Lidar observations of large-amplitude mountain waves in the stratosphere above Tierra del Fuego, Argentina

KAIFLER, N.; KAIFLER, B.; DÖRNBRACK, A.; RAPP, M.; HORMAECHEA, J. L.; DE LA TORRE, A.

Scientific Reports

Nature Publishing Group

Lugar: Londres; Año: 2020 vol. 10

Large-amplitude internal gravity waves were observed using Rayleigh lidar temperature soundingsabove Rio Grande, Argentina ( 54◦S , 68◦W ), in the period 16?23 June 2018. Temperatureperturbations in the upper stratosphere amounted to 80 K peak-to-peak and potential energydensities exceeded 400 J/kg. The measured amplitudes and phase alignments agree well withoperational analyses and short-term forecasts of the Integrated Forecasting System (IFS) of theEuropean Centre for Medium-Range Weather Forecasts (ECMWF), implying that these quasi-steadygravity waves resulted from the airflow across the Andes. We estimate gravity wave momentumfluxes larger than 100 mPa applying independent methods to both lidar data and IFS model data.These mountain waves deposited momentum at the inner edge of the polar night jet and led to along-lasting deceleration of the stratospheric flow. The accumulated mountain wave drag affectedthe stratospheric circulation several thousand kilometers downstream. In the 2018 austral winter,mountain wave events of this magnitude contributed more than 30% of the total potential energydensity, signifying their importance by perturbing the stratospheric polar vortex.