The Diurnal Variation Of Geo-electric Field Along The Longitude And Latitude Chains In China Mainland And Its Physical Interpretation

This paper has studied the time and frequency characteristics of the geo-electric field diurnal variation along the two longitude chains and the two latitude chains, using the data of the geo-electric field observed at the40stations along the chains. Accordingly, the following significant results are obtained:the semi-diurnal wave of the diurnal variation with two-fluctuation changes appears chiefly at most of the stations, near before and after the noon; according to the big to small order of the FFT amplitude spectrums, the main periods of the diurnal variation have12.4h/12h,8h,24h, etc, which are in accordance with the periods of the tidal harmonic components; the diurnal variation has the latitude effect which peak-to-valley amplitude gradually becomes bigger/smaller with the latitude of the station reduced/increased, and also has the longitude effect which phase difference agrees with the local-time difference between the stations in a same latitude; Furthermore, the amplitude of the diurnal variation is related with the Loyd season, which reduces orderly in J-, E-and D-seasons. The possible reasons which cause the main periodic components of the diurnal variation have been discussed, as a result, it is believed that There are some correlations between geo-electric field and variational geomagnetic field. However, the geo-electric field diurnal variation is not only related to variational geomagnetic field, it also involves changes of underground medium. So, the geo-electric field diurnal variation is a complex process, which closely related to both Space electromagnetic activities and changes of underground medium. the variation of the ground eddy current intensity caused by lunisolar tidal forces and the space electromagnetic activity aroused by the solar wind jointly produce the semi-diurnal period components of the geo-electric diurnal variation.