CONICET | Buscador de Institutos y Recursos Humanos

The Antarctic peninsula and Patagonia region (the south of South America) haverecently been identiﬁed as the regions with the highest gravity-wave activity in theworld. In this work, the generation and propagation of gravity waves in the Patagoniaregion in an event of strong wave activity from 30 October 1995?1 November 1995 isexamined by means of radiosonde measurements and simulations with the WeatherResearch and Forecasting (WRF) model. The waves are generated by strong surfacewinds found near the Andes mountains at a latitude of 49?51◦ S. The strong low-levelwinds are related to an extratropical cyclone that propagates southeastward in theSouth Paciﬁc ocean and approaches the western coast of the continent. The wavespropagate southeast toward Tierra del Fuego and they continue their propagationover the Drake Passage. They are found to propagate long meridional (lateral) dis-tances due to the shear background conditions. This fact is corroborated with WRFsimulations and a novel technique that combines wavelet analysis and backwardray-tracing. Therefore, this work provides further evidence that high gravity-waveactivity found by several studies over Drake Passage may have an orographic origin.During the orographic wave event, which lasts about 72 hours, the horizontalwavelength is unexpectedly found to change day-to-day. The analysis shows thatchanges in the near-surface meteorological conditions produced by the cyclonepassage may trigger different components of the forcing orography. The orographicwaves propagate toward their critical levels, which are found at 25 km and above.The radiosonde measurements show that the wave is breaking continuously along a wide altitude range; this ﬁnding from measurements supports the picture of continuous wave erosion along the ray path instead of abrupt wave-breaking for the examined wave event.

enviar mensaje