Magnetic fields due to sea tides in the english channel |
| |
| Authors: | JA Donato CD Honebon WGV Rosser |
| |
| Institution: | Physics Department, University of Exeter, Exeter Great Britain |
| |
| Abstract: | The M2 (12.42-h period) magnetic field variation present at night in the United Kingdom can be interpreted in terms of sea tides, the main contribution being from the Atlantic Ocean. Osgood et al. (1970) observed a difference between the M2-variations in the total magnetic field (F) variations at Sidmouth (0.8 km from the coast) and Exeter (16 km from the coast) of amplitude 0.8 γ, which must be due to local effects. Analysis of the phase of this difference between Exeter and Sidmouth has shown that it cannot be due entirely to tidally induced electric current systems confined to the English Channel. Measurements with two three-component magnetometers have shown that the night-time variations in the north-south (H) component of 12.42-h period are significantly different at Sidmouth and Exeter. The difference in H is in phase with the expected electric potential difference across Devon due to the difference in the phases of the sea tides in the English Channel and the Bristol Channel. The results of Donato and Rosser (1973) on micropulsations suggest the existence of a region of high conductivity under Exeter. If this connects the English Channel to the Bristol Channel, a current will flow beneath Exeter giving a difference in the M2-variations in H at Exeter and Sidmouth. This difference in H dominates the M2-variations in the total magnetic field (F) variations at Exeter and Sidmouth measured by Osgood et al. (1970). |
| |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
