Identification of high‐latitude acoustic gravity wave sources using the Goose Bay HF Radar

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Abstract
Observations of medium‐scale acoustic gravity waves using the Goose Bay HF radar are presented. Data were examined for the period of November and December 1991, and days that showed evidence of traveling ionospheric disturbances (TIDs) were selected for analysis. TIDs were identified in the HF radar data by quasi‐periodic enhancements of the power in the ground‐scattered portion of the radar signal. Various parameters were determined from the data, including the wave frequency, the wavelength, the propagation direction, and the phase velocity. It was found that multiple wave packets from multiple directions are often present simultaneously. Source times and locations were identified from data from 2 days, December 5 and 6, 1991, and these were compared with data from the Greenland magnetometer chain. The source times and locations were found to correspond to sudden magnetometer deflections, indicating the correlation of gravity wave sources with the occurrence of ionospheric electrojet current surges. Finally, the source times and locations were examined in local time and magnetic latitude, and it was found that the sources were clustered in two locations: near the magnetospheric cusp; and near 1600 MLT at about 75° magnetic latitude.