Investigating the Predictive Power of Magnetohydrodynamic Models for Geomagnetically Induced Currents in the UK

Florczak, Ewelina; Beggan, Ciaran; Whaler, Kathy. 2021 Investigating the Predictive Power of Magnetohydrodynamic Models for Geomagnetically Induced Currents in the UK. [Poster] In: European Space Weather Week 2021, Glasgow, UK, 25-29 Oct 21. (Unpublished)

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Rapid magnetic field fluctuations associated with space weather events can induce geomagnetically induced currents (GICs) in conductive structures on the Earth’s surface. Since space weather and GICs can be damaging to various technological systems and human activity, a good forecasting capability is important in order to mitigate their impacts. We used currently available magnetohydrodynamic (MHD) models of the magnetosphere and ionosphere, (SWMF, SWMF coupled with RCM, GUMICS-4 and Gorgon) to simulate ground magnetic field variations for the 7/8 September 2017 event, based on solar wind parameters propagated to the simulation domain. Modelled values of the northward (Bx) and eastward (By) magnetic field components show differences in both amplitude and temporal variability compared to the corresponding measurements, acquired via INTERMAGNET, from three UK observatories: Hartland, Eskdalemuir and Lerwick. Results indicate the accuracy of ground magnetic field forecast decreases with increasing latitude. By component tends to be predicted more accurately than Bx. It was found that the SWMF performs best in Bx forecast. Coupling with the Rice Convection Model (RCM) overestimates the field value causing poor agreement with measurements. By is best predicted by the Gorgon model. Despite being the most accurate in terms of Bx, the SWMF shows the largest error in By forecast. The resulting northward and eastward geoelectric field components were calculated from the magnetic field values using magnetotelluric transfer functions, which were then extrapolated to compute the GIC for the high-voltage UK power network. The GIC generated by a uniform electric field of 1 V/km shows that substations (nodes) located near coastlines are affected the most. Those nodes were then selected for further investigation. Error analysis suggests that GICs computed from modelled values are in closer agreement with GICs computed from our estimates of the actual geoelectric field for nodes at higher latitudes, where the SWMF performs the best. The GICs computed for substations at lower latitudes show larger discrepancies. Here, values inferred from GUMICS-4 tend to be the most accurate, despite its rather average performance in B-field forecast. Since the accuracy of the simulation of ground B-fields by MHD models included in this study is rather unsatisfactory, attempts to improve their prediction ability will be considered. Applying a method, commonly used in climate modelling, known as downscaling may potentially enhance the forecast accuracy by introducing smaller scale local variations in global variables simulated by each model.

Item Type: Publication - Conference Item (Poster)
NORA Subject Terms: Earth Sciences
Space Sciences
Date made live: 15 Nov 2021 10:16 +0 (UTC)

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