OUYANG Xin-Yan,
ZHANG Xue-Min,
SHEN Xu-Hui et al
.2013.Background features of Schumann resonance observed in Yunnan, southwestern China.Chinese Journal Of Geophysics,56(6): 1937-1944,doi: 10.6038/cjg20130616
1. School of Earth and Space Sciences, Peking University, Beijing 100087, China;
2. Institute of Earthquake Science, China Earthquake Administration, Beijing 100036, China;
3. DFH Satellite Co. Ltd., Beijing 100094, China
This paper presents the background features of Schumann resonance (SR) observed at Yongsheng observatory in Yunnan, southwestern China. Through obtaining the hourly average of the frequency and power spectral density (PSD) of the lowest three SR modes, we analyzed diurnal variation of SR frequency and PSD both in BNS and BEW components around equinoxes and solstices. Diurnal variation of SR PSD is found to be related to the dominant intervals of Asian, African and American thunderstorm centers and the relative position of the observatory to three thunderstorm centers. Diurnal variation of SR frequency is more complicated. SR frequency and PSD at the lowest three modes around summer solstice and autumn equinox are more changeable than that in spring equinox and winter solstice. The daily median of SR peak frequency in 2011 shows that seasonal variation of peak frequency is blurry, while annual variation of daily median of PSD shows a clear seasonal variation which resembled half a period of sine curve and was symmetrically distributed before and after July. The seasonal variation of PSD is in accordance with that of lightning activities. Frequency of the first mode is about at 7.5 Hz both in BNS and BEW components. However, with the higher mode, SR frequency in BNS component is 0.5 Hz larger than that in BEW component. The cause of this frequency shift is not clear yet.
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