The Correction of Shipboard Magnetic Observations

Roden, Robert B.; Mason, Cathy

doi:10.1111/j.1365-246x.1964.tb06310.x

Cited by 11 publications

(3 citation statements)

References 3 publications

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“…The reduction problems of marine magnetic surveys have received more attention because cross-overs cannot be made rapidly enough to provide suitable checks and because of the technical difficulties of maintaining buoyed local base stations. The characteristics of a daily magnetic variation at sea were investigated by Hill and Mason (1962) in the English Channel area, subsequently Roden and Mason (1964) discussed the prediction of the variation at a point between two widely separated observatories using data from the Indian Ocean. They concluded that a suitably weighted average of the two stations provided the most valuable estimate of the variations at the intermediate point.…”

Section: Introductionmentioning

confidence: 99%

Diurnal Corrections to Magnetic Surveys—an Assessment of Errors*

Riddihough

1971

Geophysical Prospecting

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The comparison of a group of continuous total field stations in Ireland with the record of the total field from Valentia Observatory enables the errors which would be involved in using the Observatory as a diurnal correction base to be examined. For the most part, for a single correction, these errors lie between ± 2 and ± 6 gammas. However, they have three notable characteristics: (i) they are not closely dependent on the magnetic ‘noisiness’ of the day, (ii) they are only marginally reduced by the application of station‐base time differences and (iii), they are strongly related to differences between the amplitude of the daily magnetic variation at the station and at the base. A permanent geographical basis for the latter differences enables a system for the estimation of the errors to be proposed.

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Section: Introductionmentioning

confidence: 99%

Diurnal Corrections to Magnetic Surveys—an Assessment of Errors*

Riddihough

1971

Geophysical Prospecting

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“…Walker [5] was the first to use the method of geographic interpolation of latitude and longitude to calculate the geomagnetic diurnal variation correction in the magnetic measurement of the British Isles. Roden [6] found that a single station cannot effectively correct the far-distance measurement area when correcting the daily variation in magnetic measurement observation data. He proposed using the separation reconstruction method and the weighted average method, which have equivalent calculation accuracy, but the weighted average method is faster and more convenient.…”

Section: Introductionmentioning

confidence: 99%

A Prediction Model of Marine Geomagnetic Diurnal Variation Using Machine Learning

Xiong,

Bian,

Liu

et al. 2024

Applied Sciences

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Geomagnetic diurnal variation significantly influences the precision of marine magnetic measurements. Precise estimation of this variation is crucial for enhancing the accuracy of offshore magnetic surveys. To address the challenges in achieving the desired accuracy with current estimation methods for geomagnetic diurnal variation, this study introduces a high-precision estimation model that integrates support vector machine (SVM) and random forest (RF) techniques. Initially, the data preprocessing phase includes an innovative extreme value adjustment method to rectify the temporal discrepancies across different stations, alongside employing the base period technique for daily baseline correction. Subsequently, we construct models to capture the daily variation trends at various times, facilitating an in-depth analysis of the diurnal variation patterns. The culmination of this process involves employing a fusion model algorithm to compute the diurnal variations across all stations comprehensively. Comparative analyses with conventional methods, such as distance weighting, bifactor weighting, and latitude weighting, reveal that our proposed model achieves a significant reduction in the root mean square error (RMSE) by an average of 31%, decreases the mean absolute error (MAE) by 35%, and enhances the Pearson correlation coefficient by 20% on average. These improvements underscore the superior accuracy of our geomagnetic diurnal variation estimation model.

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“…Loncarevic (1963), Nettleton et al (1962), Allan et al (1962) and more recently Valliant et al (1976) carefully analysed possible sources of error in gravity measurements. Roden and Mason (1964)and Riddihough (1971) have studied the errors due to incorrect diurnal corrections to magnetic observations using simultaneous observations of magnetic field strength at several locations. Haworth (1971), Wells (1976), Johnson (1971), and Foster et al (1971) have used statistical methods to model marine geophysical survey errors by applying various corrections to observed values in order to reduce discrepancies between values measured at trackline intersections.…”

Section: Introductionmentioning

confidence: 99%

Crossover differences as an indication of survey accuracy

Swan

Young

1978

Marine Geophysical Researches

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Abstract. Differences in values obtained at trackline crossovers can be used to give an indication of the overall accuracy of marine geophysical surveys. A study of the statistical validity and interpretative value of several parameters commonly used to summarize crossover discrepancies has been made. It was found that the interpretation of commonly reported statistical parameters such as standard deviation and R.M.S. error can be complicated by the presence of a systematic error in the survey data, by possible nonnormalities in the error distribution, or by the use of a distribution of positive differences. A standard procedure for the analysis of survey error on the basis of crossover discrepancies is outlined, including techniques for estimating systematic survey errors and for the evaluation of the normality of the observed distribution of crossover discrepancies.

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The Correction of Shipboard Magnetic Observations

Cited by 11 publications

References 3 publications

Diurnal Corrections to Magnetic Surveys—an Assessment of Errors*

Diurnal Corrections to Magnetic Surveys—an Assessment of Errors*

A Prediction Model of Marine Geomagnetic Diurnal Variation Using Machine Learning

Crossover differences as an indication of survey accuracy

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