Estimating external magnetic field differences at high geomagnetic latitudes from a single station

Beggan, Ciarán; Billingham, L.; Clarke, Ellen

doi:10.1111/1365-2478.12641

Cited by 7 publications

(5 citation statements)

References 36 publications

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“…In our ST-IDW interpolation we assume an isotropic change of the field. However, there are differences in how the field varies in North-South and East-West directions [ 55 ]: for example, ionosphere is persistent over 1000 km in East-West direction and 800 km in the North-South direction. This could be integrated into our method, for example by either changing the form and size of the spatio-temporal kernel (e.g.…”

Section: Discussionmentioning

confidence: 99%

“…We obtained INTERMAGNET data from three observatories and three temporal periods with different levels of geomagnetic activity, which is a common way to assess how magnetic interpolation methods perform under varied conditions [ 54 , 55 ]. Our goal was to assess how the accuracy of our method varied with: i) the level of disturbance in the geomagnetic field at that location and time, ii) the latitude of the tracking location, and iii) the parameters related to the spatio-temporal kernel (i.e., the number of selected satellite points and the minimum and average spatial distance from the trajectory point to the respective satellite points).…”

Section: Methodsmentioning

confidence: 99%

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Fusion of wildlife tracking and satellite geomagnetic data for the study of animal migration

et al. 2021

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Background Migratory animals use information from the Earth’s magnetic field on their journeys. Geomagnetic navigation has been observed across many taxa, but how animals use geomagnetic information to find their way is still relatively unknown. Most migration studies use a static representation of geomagnetic field and do not consider its temporal variation. However, short-term temporal perturbations may affect how animals respond - to understand this phenomenon, we need to obtain fine resolution accurate geomagnetic measurements at the location and time of the animal. Satellite geomagnetic measurements provide a potential to create such accurate measurements, yet have not been used yet for exploration of animal migration. Methods We develop a new tool for data fusion of satellite geomagnetic data (from the European Space Agency’s Swarm constellation) with animal tracking data using a spatio-temporal interpolation approach. We assess accuracy of the fusion through a comparison with calibrated terrestrial measurements from the International Real-time Magnetic Observatory Network (INTERMAGNET). We fit a generalized linear model (GLM) to assess how the absolute error of annotated geomagnetic intensity varies with interpolation parameters and with the local geomagnetic disturbance. Results We find that the average absolute error of intensity is − 21.6 nT (95% CI [− 22.26555, − 20.96664]), which is at the lower range of the intensity that animals can sense. The main predictor of error is the level of geomagnetic disturbance, given by the Kp index (indicating the presence of a geomagnetic storm). Since storm level disturbances are rare, this means that our tool is suitable for studies of animal geomagnetic navigation. Caution should be taken with data obtained during geomagnetically disturbed days due to rapid and localised changes of the field which may not be adequately captured. Conclusions By using our new tool, ecologists will be able to, for the first time, access accurate real-time satellite geomagnetic data at the location and time of each tracked animal, without having to start new tracking studies with specialised magnetic sensors. This opens a new and exciting possibility for large multi-species studies that will search for general migratory responses to geomagnetic cues. The tool therefore has a potential to uncover new knowledge about geomagnetic navigation and help resolve long-standing debates.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Fusion of wildlife tracking and satellite geomagnetic data for the study of animal migration

et al. 2021

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“…As the effect of the ionosphere and magnetosphere is latitude-dependent (e.g., Beggan et al 2021;Chulliat et al 2020) quantifying the external field effects is not difficult. However, as these uncertainties are time-dependent (daily, seasonal, solar cycle) providing an 'average' error for these sources is difficult though possible, as long as it is clear to the user what the uncertainties represent (Beggan et al 2018). We focus on the internal parts of the IGRF that are missing from the model.…”

Section: Graphical Abstractmentioning

confidence: 99%

Evidence-based uncertainty estimates for the International Geomagnetic Reference Field

Beggan¹

2022

Preprint

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<p>The International Geomagnetic Reference Field (IGRF) is a multi-institute model of the Earth&#8217;s magnetic field, compactly described by sets of up to 195 spherical harmonic (Gauss) coefficients to degree and order 13, which allows the continuous evaluation of the field at any location and time on or above the surface. It is developed from satellite and ground-based magnetometer data and describes the large-scale variation of the magnetic field in space and time under quiet conditions. While much effort has been made on improving the forecast of the secular variation of the field over the five-year intervals between release and renewal, less emphasis has been placed on understanding the spatial errors from a user point of view. We estimate the large-scale time-invariant spatial uncertainty of the IGRF based on the globally averaged misfit of the model to semi-independent ground-based measurements at repeat stations and observatories between 1980 and 2021. As the ground measurements are reduced to quiet-time values, the external field is minimized. We find the 68.3% confidence interval is 87 nT in the North (X) component, 73 nT in the East (Y) component and 114 nT in Vertical (Z) component. Due to the Laplacian distribution of the residuals, the standard deviations are larger at 144, 136 and 293 nT, respectively.</p>

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“…The crustal field from local rocks is relatively weak in comparison (generally <1,000 nT) and may be regarded as static on geologic time scales, but electrical currents flowing in the upper atmosphere driven by the variable solar wind can cause large and rapid fluctuations on time scales of minutes to hours. During severe magnetic storms, the intensity of the electrical currents reach over 3,000 nT and can cause variations of several degrees in the geomagnetic-field vector direction, particularly at high latitudes close to the auroral regions (Beggan et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Quantifying Global and Random Uncertainties in High Resolution Global Geomagnetic Field Models Used for Directional Drilling

Beggan

Macmillan

Brown

et al. 2021

SPE Drilling &Amp; Completion

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Summary Total field strength, declination, and dip angle of the Earth's magnetic field, in conjunction with gravity, are used by magnetic-survey tools to determine a wellbore's location. Magnetic field values may be obtained from global models that, depending on the model, have a wide range of spatial resolution at the Earth's surface from large scale (3000 km) to small scale (28 km). The magnetic field varies continuously in both time and space, so no model can fully capture the complexity of all sources; hence, there are uncertainties associated with the values provided. The SPE Wellbore Positioning Technical Section/Industry Steering Committee on Wellbore Surveying Accuracy (ISCWSA) published their original measurement-while-drilling (MWD) error model in 2000. Such models and uncertainties define positional error ellipsoids along the wellbore, which assist the driller in achieving their geological target, in addition to aiding collision avoidance. With the recent update to Revision 5 of the ISCWSA error model, we have reassessed the uncertainties associated with our latest high-resolution global magnetic field model. We describe the derivation of location-specific global and random uncertainties for use with predicted geomagnetic values from high-resolution models within magnetic MWD survey-tool-error models. We propose a sophisticated approach to provide realistic values at different locations around the globe; for example, we determine separate errors for regions where the models have high spatial resolution from aeromagnetic data compared to regions where only satellite data are available. The combined uncertainties are freely available via a web service with which the user can also see how they vary with time. The use of the revised uncertainty values in the MWD-error model, in most cases, reduces the positional error ellipsoids and allows better use of the increased accuracy from recent improvements in geomagnetic modeling. This is demonstrated using the new uncertainty values in the MWD-error model for three standard ISCWSA well profiles. A fourth theoretical well offshore Brazil where the vertical magnetic field is weak shows that with drillstring interference correction relying on the more uncertain magnetic dip, the positional error ellipsoids can increase. This is clearly of concern for attaining geological targets and collision avoidance.

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Estimating external magnetic field differences at high geomagnetic latitudes from a single station

Cited by 7 publications

References 36 publications

Fusion of wildlife tracking and satellite geomagnetic data for the study of animal migration

Fusion of wildlife tracking and satellite geomagnetic data for the study of animal migration

Evidence-based uncertainty estimates for the International Geomagnetic Reference Field

Quantifying Global and Random Uncertainties in High Resolution Global Geomagnetic Field Models Used for Directional Drilling

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