Incoherent scatter observations of tides in the lower thermosphere at high latitudes

摘要: Abstract Incoherent scatter measurements at high latitudes show that in the height range between 100 and 130 km velocity of neutral atmosphere shows a prominent sinusoidal component with 12-hour period. The variation phase for this is approximately constant from day to day, corresponds predicted (2,4) mode global tide; greater heights, much slower (2,2) mode. amplitude semi-diurnal as measured EISCAT deep modulation period about 53 hours, interpreted result non-linear interaction mesosphere tide most planetary wave these latitudes. A diurnal also observed which even day-to-day variability. There good qualitative agreement made EISCAT, Chatanika Sondrestrom, especially semidiurnal component. reasonable predictions using various models lower thermosphere, but effect ion on-drag driven by magnetospheric convection difficult model detail, Sondrestrom. Tidal modes are temperature.