Abstract
Abstract. Zenith-directed Fabry-Perot Spectrometer (FPS) and 3-Field Photometer (3FP) observations of the λ630 nm emission (~240 km altitude) were obtained at Davis station, Antarctica, during the austral winter of 1999. Eleven nights of suitable data were searched for significant periodicities common to vertical winds from the FPS and photo-metric variations from the 3FP. Three wave-like events were found, each of around one or more hours in duration, with periods around 15 minutes, vertical velocity amplitudes near 60 ms–1 , horizontal phase velocities around 300 ms–1 , and horizontal wavelengths from 240 to 400 km. These characteristics appear consistent with polar cap gravity waves seen by other workers, and we conclude this is a likely interpretation of our data. Assuming a source height near 125 km altitude, we determine the approximate source location by calculating back along the wave trajectory using the gravity wave property relating angle of ascent and frequency. The wave sources appear to be in the vicinity of the poleward border of the auroral oval, at magnetic local times up to 5 hours before local magnetic midnight.Key words. Meteorology and atmospheric dynamics (thermospheric dynamics; waves and tides)
Highlights
Generation of atmospheric gravity waves in or near the auroral electrojets is well documented
In four of the other cases, the ‘wave-like’ event in the FabryPerot Spectrometer (FPS) wind appeared to be due to a quasi-periodic movement into and out of the FPS field-of-view of a region of upward wind at the poleward edge of the auroral oval
For these cases the FPS and 3-Field Photometer (3FP) intensities showed no significant power at the detected frequency, but instead, showed a decline and recovery, with a minimum centred on the time of occurrence of the wind event
Summary
Generation of atmospheric gravity waves in or near the auroral electrojets is well documented. Evidence of ionospheric waves travelling from the polar regions Optical studies revealed evidence for gravity waves with auroral sources. Herrero et al (1984) using a FabryPerot Spectrometer (FPS) observed wave-like vertical velocity and temperature fluctuations in oxygen λ630 nm emission data (∼240 km altitude) at high northern latitudes, which appeared consistent with their model of a heating source at 120 km altitude. Rees et al (1984b) considered the implications of these data for the generation of gravity waves
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