BISPECTRAL ANALYSIS OF THE MF RADAR WINDS

Bispectral analysis and dynamic spectral analysis are applied to the wind data of June, 1997, measured by MFradar in Yamagawa, Japan, to investigate nonlinear interactions among planetary waves, tidal waves and gravity waves in the mesopause region. Results show that there were strong diurnal tide, semi-diurnal tide and quasi-two-day wave activities, and some groups of three waves whose frequencies satisfied resonant conditions coexisted and their phases were coherent, which may suggest non-linear wave-wave interactions. Discussions on these nonlinear interactions between different kinds of waves are presented.