Lower-thermospheric tidal variability as diagnosed by rotated empirical orthogonal function analysis

Understanding tidal variability in the lower thermosphere is essential for accurate prediction of ionospheric weather. In this study, we investigate lower-thermospheric tidal variability by applying rotated empirical orthogonal function (EOF) analysis to tides in temperature and wind fields at 80-110 km obtained from the JAWARA reanalysis over the past two decades. The rotated EOF analysis identifies the dominant modes of tidal variability as functions of latitude and altitude. The leading EOF modes exhibit latitudinal structures similar to the Hough modes predicted by classical tidal theory. Their principal component time series are compared with various meteorological indices (such as ENSO and QBO indices), allowing us to assess the relative importance of different meteorological processes for different tidal components (such as DE3 and SW2).