Abstract
A marine magnetic survey was conducted over the Dellwood Knolls area of the northeast Pacific in September 1977 using a proton precession magnetometer and Loran-C positioning. Geomagnetic field reference stations were located at Victoria and Port Hardy. In addition, a recently developed ocean bottom magnetometer was deployed in the survey area. The cross-over error, a measure of survey accuracy, and the factors contributing to it are discussed. In high magnetic gradient regions, the part of the error related to the uncertainty in ship position implies that the repeatability of the Loran-C navigation system is of the order of 30 metres. Part of the error is also due to time variations of the geomagnetic field. This latter effect can be significantly reduced by correcting to a well located reference station. Because of the areal distribution of the geomagnetic coast effect, a land station close to the survey area may not be as effective as a more distant site. Referencing to an ocean bottom magnetometer, at least to moderate levels of disturbance, is comparable to correcting to a well located land station. Using a combination of land and ocean bottom reference data produced a reduction in the cross-over error from 25 to 11 nT for this survey, effectively removing the geomagnetic variation term. This technique should prove even more useful for surveys conducted during periods of higher geomagnetic activity.
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References
Barrett, D. L.: 1968, ‘Frequency Modulation of a Shipborne Proton Magnetometer Signal Due to the Hydrodynamic Instability of the Towed Vehicle’, J. Geophys. Res. 73, 5327–34.
Bullard, E. C., and Mason, R.G.: 1961, ‘The Magnetic Field Astern of a Ship’, Deep-Sea Res. 8, 20–27.
Caner, B., Auld, D. R., Dragert, H., and Camfield, P.A.: 1971, ‘Geomagnetic Depth-Sounding and Crustal Structure in Western Canada’, J. Geophys. Res. 76, 7181–7201.
Dosso, H.W.: 1965, ‘The Electric and Magnetic Fields in a Stratified Flat Conductor for Incident Plane Waves’, Can. J. Phys. 43, 898–909.
Eaton, R. M.: 1975, ‘Tests of Loran-C Performance’, Can. Aero. Space J. 21, 129–32.
Hill, M. N., and Mason, C. S.: 1962, lsDiurnal Variation of the Earth's Magnetic Field at Sea’, Nature, 195, 365–66.
Law, L. K.: 1978, ‘An Ocean Bottom Magnetometer: Design and First Deployment Near the Explorer Ridge’, Trans. Am. Geophys. Union, 59, 235. (abstract)
Law, L. K., and Greenhouse, J. P.: 1978, ‘Ocean Bottom Magnetometer Results from the Juan de Fuca Ridge’, Trans. Am. Geophys. Union, 59, 1055. (abstract)
Nienaber, W., Dosso, H. W., Law, L. K., Jones, F. J., and Ramaswamy, V.: ‘Electromagnetic Induction in the Vancouver Island Region: Field Station and Analogue Model Results’, J. Geomagn. Geoelectr. (In Press)
Raff, A. D., and Mason, R. G.: 1961, ‘Magnetic Survey off the West Coast of North America, 40°N to 52°N latitude’, Geol. Soc. Am. Bull. 72, 1267–70.
Roden, R. B., and Mason, C. S.: 1964, ‘The Correction of Shipboard Magnetic Observations’, Geophys. J. Roy. Astron. Soc. 9, 9–13.
Riddihough, R. P.: 1967, ‘Marine Geophysical Investigations off the North Coast of Ireland’, Ph.D. Thesis, University of London.
Riddihough, R. P.: 1971, ‘Diurnal Corrections to Magnetic Surveys — An Assessment of Errors’, Geophys. Prosp. 19, 551–67.
Swan, D., and Young, I. F.: 1978, ‘Crossover Differences as an Indication of Survey Accuracy’, Marine Geophys. Res. 3, 393–400.
Vine, F. J., and Wilson, J. T.: 1965, ‘Magnetic Anomalies Over a Young Oceanic Ridge off Vancouver Island’, Science, 150, 485–89.
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Contribution from the Earth Physics Branch No. 824.
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Auld, D.R., Law, L.K. & Currie, R.G. Cross-over error and reference station location for a marine magnetic survey. Marine Geophysical Researches 4, 167–179 (1979). https://doi.org/10.1007/BF00286403
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DOI: https://doi.org/10.1007/BF00286403