General features of 4–24-day waves in sporadic E-layer variations and their connection with equatorial stratospheric QBO

This paper summarizes the results of our research in sporadic E-layer (Es) dynamics with planetary wave periods (2–32 days) in the Northern Hemisphere and its connection with equatorial stratospheric quasi-biennial oscillation (QBO). The interpolation of averaged daily values of Es   highest frequency (foEsfoEs), amplitudes of 2–32-day foEsfoEs oscillations and filtered 16-day foEsfoEs oscillations is conducted on the basis of foEsfoEs measurement data for 1965–1989 from the world ionosonde network. Averaged monthly values of the zonal wind u¯ in the equatorial stratosphere at the 19–31 km height interval are used as the index of quasi-biennial oscillation of atmospheric circulation. A correlation analysis between the annual averaged values of u¯ index and the interpolated values of foEsfoEs and 4–24-day foEsfoEs oscillations showed significant correlation in the sector of longitude from 30° to 270° (to the East of Greenwich) and latitude from 15°N to 75°N. We have developed an original algorithm for detecting a spatial motion in scalar field of any interpolated geophysical parameter in a specific local area. The algorithm is used to obtain zonal and meridional projections of local displacement of the 4–24-day foEsfoEs wave perturbation field in the Northern Hemisphere. A connection between the annual prevailing directions of 4–24-day foEsfoEs wave perturbations and the QBO phase (eastern or western) of atmospheric circulation is revealed on the basis of correlation analysis. The strongest correlation is discovered in the area around 60° N, 120° E in the case of filtered 16-day foEs oscillation field.