科研之友
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摘要
Sea-surface and sea-bottom measurements at the same location can yield different results of the geomagnetic field due to the disturbance of seawater cutting geomagnetic lines and relevant electromagnetic induction. Although previous studies more or less document such differences, little measurements can characterize their space-temporal variations. This paper presents observations from a recent experiment in the southwest subbasin of the South China Sea by using a 4-km-long deep-sea geomagnetic buoy. The data display a complete measurement of the geomagnetic field in the seawater column at all depths, allowing us to analyze its vertically-varying characteristics in the total intensity and phase. Compared with three nearby observatories with a Sq model, observed diurnal variations show similarity in magnetic quiet periods. However, during the magnetic disturbance period, notable discrepancies exist, probably caused by the effects of diverse sub-seafloor electric media on induced current. This study is significant in evidencing the changes of the geomagnetic field with both time and depth in an abyssal basin, as well as in advising for the design of the diurnal variation observatory in marine magnetic surveys.
- 出版日期2017-3
- 单位广州海洋地质调查局; 中国地震局
