Possible Physical Mechanisms for Quasi 23-day Oscillation in DW1 Tidal Variability in the MLT Region

Atmospheric tides observed in the Mesosphere and lower Thermosphere (MLT) region exhibits significant long (variability period > 30 days) and short-term (variability period < 30 days) variability in amplitude and phases. We found a quasi-23 day oscillation in DW1 short-term tidal variability in both extended Canadian Middle Atmospheric Model (eCMAM) data and Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) temperature observations in the MLT region. We developed an empirical statistical model based on auto regression (AR), to predict the DW1 tidal weather as a linear combination of the 23 days of tidal weather data prior to the prediction day. AR model can predict 1-day tidal weather with an accuracy of 89% and 5-day forecast up to 65% accuracy.

The subject of the present study is to understand this quasi - 23 day oscillation observed in DW1 tidal weather and it is more difficult to explain and possibly the result of several mechanisms. we perform cross-correlations and bi-spectral analysis techniques to investigate the plausible sources and mechanisms of this including wave-mean flow interaction, wave-wave interaction, and heating, and a combination of them using thermodynamic budget equation form eCMAM.