Planetary wave oscillations in sporadic E layer occurrence at Wuhan

Abstract

Abstract Quasi 6-day oscillations in E s occurrence were observed to occur in relation with planetary wave activity at Wuhan, China (30.6°N, 114.5°E). Wavelet analysis of E s occurrence time series revealed that a strong 5- to 7-day oscillation was present during the period from about day 120 to 137 of 2003. The same quasi 6-day planetary wave oscillation was also found to dominate the spectrum of concurrent wind data measured in the 80- to 100-km region by a meteor radar, in agreement with the E s occurrence. There is also a great deal of similarity between the 5- to 7-day band-pass filtered waveforms of E s occurrence and the wind data. By estimating the wave phase changes with altitude, the quasi 6-day PW in the zonal wind was found to be in phase with the sporadic E layer critical frequency, f o E s, at about 115 km, close to the observed E s height. The quasi 6-day PW modulation was also present in the amplitude of the 12-h and 24-h periodicities which existed in the f o E s time series. The present results provide new evidence in favor of a planetary wave indirect role on E s formation through the modulation of tides, which in line with previous studies by Haldoupis and Pancheva (2002), and Pancheva et al. (2003).