Earth Planets Space, Vol. 60 (No. 6), pp. 647-652, 2008
Xiaomin Zuo1,2,3,4 and Weixing Wan1
1Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029, China
2Mathematics and Physics Department, China University of Geosciences, 430074, China
3Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, China
4Graduate School, Chinese Academy of Sciences, China
(Received September 23, 2007; Revised November 26, 2007; Accepted January 7, 2008; Online published July 4, 2008)
Quasi 6-day oscillations in Es occurrence were observed to occur in relation with planetary wave activity at Wuhan, China (30.6°N, 114.5°E). Wavelet analysis of Es 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 Es occurrence. There is also a great deal of similarity between the 5- to 7-day band-pass filtered waveforms of Es 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, foEs, at about 115 km, close to the observed Es 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 foEs time series. The present results provide new evidence in favor of a planetary wave indirect role on Es formation through the modulation of tides, which in line with previous studies by Haldoupis and Pancheva (2002), and Pancheva et al. (2003).
Key words: Sporadic E layers, planetary waves, atmospheric tides, PW modulation of tides.