Planetary wave oscillations in sporadic E layer occurrence at Wuhan
© The Society of Geomagnetism and Earth, Planetary and Space Sciences (SGEPSS); The Seismological Society of Japan; The Volcanological Society of Japan; The Geodetic Society of Japan; The Japanese Society for Planetary Sciences. 2008
Received: 23 September 2007
Accepted: 7 January 2008
Published: 4 July 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).