A measuring profile was set up in both sides of the Qiongzhou strait to carry out the simultaneous observation of three component geomagnetic variation. The observed synchronous geomagnetic vertical variations of shor...A measuring profile was set up in both sides of the Qiongzhou strait to carry out the simultaneous observation of three component geomagnetic variation. The observed synchronous geomagnetic vertical variations of short periods were reversed on the both sides of the strait. It means that there is a abnormal concentration of electric current in the area. Spatial wave number domain analysis was performed by Sompi spectral analysis for the spatial distribution and the internal and the external parts of the geomagnetic variation field were separated. Inversion of the internal field was carried out by generalized inverse matrix inversion based on singular value decomposition and the distribution of undergrond current density was obtained. The discussion suggests that this abnormal current concentration comes from current channelling effect in the Quaternary sediment in this region.展开更多
The principle of Accurately Controlled Routinely Operated Signal System (ACROSS) is introduced in this paper. A sample machine is made and tested. The experiment shows that the signal stacking technique is effective i...The principle of Accurately Controlled Routinely Operated Signal System (ACROSS) is introduced in this paper. A sample machine is made and tested. The experiment shows that the signal stacking technique is effective in improving signal to noise ratio and the sompi cepstrum method is applicable to deconvolute a set of travel times of wave elements from accurate transfer function data in frequency domain.展开更多
The monthly means of north component X of geomagnetic field from 16 observatories during 1984-1988 were analyzed using the Sompi spectral analysis technique. Most of these observatories are located in China. The analy...The monthly means of north component X of geomagnetic field from 16 observatories during 1984-1988 were analyzed using the Sompi spectral analysis technique. Most of these observatories are located in China. The analysis of the semiannual variations indicates that the latitude has no apparent effect on the X component. This clearly implies that the source field mode of semiannual variations cannot simply be described by using the P°1 mode. Using the P°1 mode to estimate the inductive scale length C in the semiannual period, the value of C at each observatory would be biased significantly. The purpose of this study is to find which kind of modes is optimal for estimating the values of C corresponding to the semiannual variations. The results show that a composite mode, involving five terms P°n(n = 1,....,5), might be a reasonable and acceptable one.展开更多
文摘A measuring profile was set up in both sides of the Qiongzhou strait to carry out the simultaneous observation of three component geomagnetic variation. The observed synchronous geomagnetic vertical variations of short periods were reversed on the both sides of the strait. It means that there is a abnormal concentration of electric current in the area. Spatial wave number domain analysis was performed by Sompi spectral analysis for the spatial distribution and the internal and the external parts of the geomagnetic variation field were separated. Inversion of the internal field was carried out by generalized inverse matrix inversion based on singular value decomposition and the distribution of undergrond current density was obtained. The discussion suggests that this abnormal current concentration comes from current channelling effect in the Quaternary sediment in this region.
文摘The principle of Accurately Controlled Routinely Operated Signal System (ACROSS) is introduced in this paper. A sample machine is made and tested. The experiment shows that the signal stacking technique is effective in improving signal to noise ratio and the sompi cepstrum method is applicable to deconvolute a set of travel times of wave elements from accurate transfer function data in frequency domain.
文摘The monthly means of north component X of geomagnetic field from 16 observatories during 1984-1988 were analyzed using the Sompi spectral analysis technique. Most of these observatories are located in China. The analysis of the semiannual variations indicates that the latitude has no apparent effect on the X component. This clearly implies that the source field mode of semiannual variations cannot simply be described by using the P°1 mode. Using the P°1 mode to estimate the inductive scale length C in the semiannual period, the value of C at each observatory would be biased significantly. The purpose of this study is to find which kind of modes is optimal for estimating the values of C corresponding to the semiannual variations. The results show that a composite mode, involving five terms P°n(n = 1,....,5), might be a reasonable and acceptable one.
