Empirical Modeling of the Geomagnetic Field for GIC Predictions

Weimer, D. R.

doi:10.1002/9781119434412.ch4

Cited by 2 publications

(2 citation statements)

References 33 publications

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“…They are generated by fast variations of the magnetic field (dB/dt) on the ground, so that fast magnetic fluctuations may have a great relevance on it. Global magnetohydrodynamics, empirical and numerical models (see for example Pulkkinen et al., 2011; Weimer, 2013, 2019, Welling, 2019) have been developed in the past to model and forecast geomagnetic perturbations at ground level responsible of GICs. However, while these models are capable of predicting the low‐frequency variations in the magnetic field, they are unable to reproduce the high‐frequency fluctuations and fast substorm perturbations that is, fluctuations at time scale shorter than 5 min.…”

Section: Discussionmentioning

confidence: 99%

Hints on the Multiscale Nature of Geomagnetic Field Fluctuations During Quiet and Disturbed Periods

2021

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Recently, investigating the behavior of some geomagnetic indices (AE indices, SYM-H and ASY-H), the Perreault-Akasofu coupling function and the Bz component of the interplanetary magnetic field, it has been displayed (Alberti et al., 2017) that the magnetic time series, associated with the geomagnetic indices, are characterized by fluctuations which present a different amount of shared information (which AbstractWe analyze the geomagnetic data recorded at 78 stations from 13 to 31 March 2015. Using the empirical mode decomposition (EMD) method, we focus our attention on geomagnetic signal due to sources which are external to the Earth, that is, due to current systems flowing in the ionosphere and magnetosphere. We analyze the short timescale fluctuations (τ < 200 min) of this magnetic signal, their dependence on magnetic latitude, magnetic local time, and geomagnetic activity. At high geomagnetic latitudes (>|60°|), these short timescale fluctuations constitute more than 30% of the external magnetic field. Their maximum contribution occurs along the auroral oval suggesting that they are mainly triggered by the ionospheric electric current systems active in these regions. A discussion of the relevance of these short timescale magnetic fluctuations to result in a more significant modeling and prediction of geomagnetically induced currents in the auroral zones is also provided. SANTARELLI ET AL.

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Section: Discussionmentioning

confidence: 99%

Hints on the Multiscale Nature of Geomagnetic Field Fluctuations During Quiet and Disturbed Periods

2021

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“…The ground‐level magnetic field, which is typically extrapolated from much higher in the magnetospheric domain, is used to drive geoelectric field models. Empirical models also exist (Weimer, 2013, 2019).…”

Section: Introductionmentioning

confidence: 99%

Toward GIC Forecasting: Statistical Downscaling of the Geomagnetic Field to Improve Geoelectric Field Forecasts

et al. 2022

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Geomagnetically induced currents (GICs) are an impact of space weather that can occur during periods of enhanced geomagnetic activity. GICs can enter into electrical power grids through earthed conductors, potentially causing network collapse through voltage instability or damaging transformers. It would be beneficial for power grid operators to have a forecast of GICs that could inform decision making on mitigating action. Long lead‐time GIC forecasting requires magnetospheric models as drivers of geoelectric field models. However, estimation of the geoelectric field is sensitive to high‐frequency geomagnetic field variations, which operational global magneto‐hydrodynamic models do not fully capture. Furthermore, an assessment of GIC forecast uncertainty would require a large ensemble of magnetospheric runs, which is computationally expensive. One solution that is widely used in climate science is “downscaling,” wherein sub‐grid variations are added to model outputs on a statistical basis. We present proof‐of‐concept results for a method that temporally downscales low‐resolution magnetic field data on a 1‐hr timescale to 1‐min resolution, with the hope of improving subsequent geoelectric field magnitude estimates. An analog ensemble (AnEn) approach is used to select similar hourly averages in a historical data set, from which we separate the high‐resolution perturbations to add to the hourly average values. We find that AnEn outperforms the benchmark linear‐interpolation approach in its ability to accurately drive an impacts model, suggesting GIC forecasting would be improved. We evaluated the ability of AnEn to predict extreme events using the FSS, HSS, cost/loss analysis and BSS, finding that AnEn outperforms the “do‐nothing” approach.

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Empirical Modeling of the Geomagnetic Field for GIC Predictions

Cited by 2 publications

References 33 publications

Hints on the Multiscale Nature of Geomagnetic Field Fluctuations During Quiet and Disturbed Periods

Hints on the Multiscale Nature of Geomagnetic Field Fluctuations During Quiet and Disturbed Periods

Toward GIC Forecasting: Statistical Downscaling of the Geomagnetic Field to Improve Geoelectric Field Forecasts

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