Neutral Wind Determination from SuperDARN Backscatter: Technique and Application to the Study of Atmospheric Waves and Tides.

摘要

The Super Dual Auroral Radar Network (SuperDARN) is a network of high-frequency (HF) radars designed to detect the horizontal motion of plasma drifting in the ionosphere over the Earth's mid- to high-latitude regions. These radars are also sensitive to ionization trails caused by meteors ablating in the upper atmosphere at mesosphere altitudes (85-100 km). Since the ionized meteor trails drift with the neutral atmosphere at these altitudes, they serve as a tracer for studying the dynamics of atmospheric waves.;To analyze the background mean wind flow and atmospheric waves, a more reliable technique was developed for identifying meteor echoes from the variety of signals detected by these radars. Applying this technique to data obtained from several mid-latitude radars in 2011 reveals a diurnal and seasonal dependence of the occurrence of meteor echoes. In addition there is a dependence on the orientation between the radar viewing direction and the background wind direction. Further analysis identifies bursts of wave activity throughout the year, showing interesting results from a particular source known as the quasi-two-day wave (QTDW). It is shown that the variability in the amplitude of the QTDW maximizes near particular longitudes across North America. Furthermore, a detailed study of non-linear interactions between the QTDW and multiple wave periods is performed. A technique known as bispectral analysis, a third-order statistical method that identifies phase coupling between harmonic frequencies and secondary waves, is used to confirm that nonlinear wave interactions exist with the QTDW, as suggested by the power spectrum. This research provides a more reliable method for identifying meteor echoes from SuperDARN measurements and furthers our understanding of atmospheric dynamics in the mesosphere.