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

Abstract

Large-amplitude internal gravity waves were observed using Rayleigh lidar temperature soundings above Rio Grande, Argentina ($$54^\circ \; \hbox {S}$$ 54 ∘ S , $$68^\circ \; \hbox {W}$$ 68 ∘ W ), in the period 16–23 June 2018. Temperature perturbations in the upper stratosphere amounted to 80 K peak-to-peak and potential energy densities exceeded 400 J/kg. The measured amplitudes and phase alignments agree well with operational analyses and short-term forecasts of the Integrated Forecasting System (IFS) of the European Centre for Medium-Range Weather Forecasts (ECMWF), implying that these quasi-steady gravity waves resulted from the airflow across the Andes. We estimate gravity wave momentum fluxes 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 a long-lasting deceleration of the stratospheric flow. The accumulated mountain wave drag affected the 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 energy density, signifying their importance by perturbing the stratospheric polar vortex.

An 18‐Year Climatology of Directional Stratospheric Gravity Wave Momentum Flux From 3‐D Satellite Observations

“…This structure is relatively unperturbed by topographically forced planetary wave activity, unlike in the NH. These factors provide ideal conditions for the propagation of mountain waves into the stratosphere and higher during winter (e.g., Kaifler et al., 2020; Liu et al., 2019).…”

SOUTHTRAC-GW: An Airborne Field Campaign to Explore Gravity Wave Dynamics at the World’s Strongest Hotspot

“…The Estación Astrónomicas Río Grande (EARG) which is located close to the airport of Rio short-term weather forecasts of clouds and precipitation. CORAL lidar data was used to study a long-term, large-amplitude stratospheric mountain wave event, and was combined with another lidar and satellite data to spatially resolve the structure of a GW (Kaifler et al 2020;Alexander et al 2020).…”

Modeling Responses of Polar Mesospheric Clouds to Gravity Wave and Instability Dynamics and Induced Large‐Scale Motions

“…These parameters were chosen to be representative of a GW packet arising from a strong lower atmosphere source of high‐frequency GWs such as mountain waves (MWs) arising over the Southern Andes. Recent lidar observations over Rio Grande Tierra del Fuego (53.8°S) well in the lee and south of the major peaks reveal MWs with amplitudes often of ∼30 K near and below ∼40 km, implying (Kaifler et al., 2020). GW imaging at ∼87 km and radar wind measurements from ∼80–100 km also reveal that under suitable propagation conditions, these MWs readily penetrate well into the MLT (D. Pautet and K. limura, private communications, 2017).…”