The Correspondence Between Sudden Commencements and Geomagnetically Induced Currents: Insights From New Zealand

Smith, A. W.; Rodger, Craig J.; Manus, Daniel H. Mac; Forsyth, C.; Rae, I. J.; Freeman, M. P.; Clilverd, Mark A.; Petersen, Tanja; Dalzell, Michael D

doi:10.1029/2021sw002983

Cited by 8 publications

(22 citation statements)

References 72 publications

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“…We note that high latitude magnetic field spikes which can cause GICs are not confined solely to geomagnetic storm conditions. At mid and low latitudes, sudden commencements are found to be a major factor in producing spikes (e.g., Smith et al, 2019;Smith et al, 2021Smith et al, , 2022), but we do not find a significant population of high latitude spikes near noon. More comparisons of the driving mechanisms of spikes at high and mid-to-low latitudes are required.…”

Section: Discussioncontrasting

confidence: 84%

“…In the main, we focus on spikes with dB/ dt > 300 nT min −1 , as spikes of this magnitude were responsible for power grid blackouts during the 2003 Halloween storm (Kappenman, 2005). The focus on large dB/dt means that our results apply to high latitudes only: more modest values of dB/dt occur at mid and low latitudes (e.g., Rogers et al, 2020;Smith et al, 2019Smith et al, , 2021Smith et al, , 2022 but will not be included in our analysis.…”

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confidence: 99%

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Solar Cycle and Solar Wind Dependence of the Occurrence of Large dB/dt Events at High Latitudes

et al. 2023

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We investigate sharp changes in magnetic field that can produce Geomagnetically Induced Currents (GICs) which damage pipelines and power grids. We use one‐minute cadence SuperMAG observations to find the occurrence distribution of magnetic field “spikes.” Recent studies have determined recurrence statistics for extreme events and charted the local time distribution of spikes; however, their relation to solar activity and conditions in the solar wind is poorly understood. We study spike occurrence during solar cycles 23 and 24, roughly 1995 to 2020. We find three local time hotspots in occurrence: the pre‐midnight region associated with substorm onsets, the dawn sector often associated with omega band activity, and the pre‐noon sector associated with the Kelvin‐Helmholtz instability (KHI) occurring at the magnetopause. Magnetic field perturbations are mainly North‐South for substorms and KHI, and East‐West for omega bands. Substorm spikes occur at all phases of the solar cycle, but maximize in the declining phase. Omega‐band and KHI spikes are confined to solar maximum and the declining phase. Substorm spikes occur during moderate solar wind driving, omega band spikes during strong driving, and KHI spikes during quiet conditions but with high solar wind speed. We show that the shapes of these distributions do not depend on the magnitude of the spikes, so it appears that our results can be extrapolated to extreme events.

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Section: Discussioncontrasting

confidence: 84%

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confidence: 99%

Solar Cycle and Solar Wind Dependence of the Occurrence of Large dB/dt Events at High Latitudes

et al. 2023

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“…Examining more than 15 years of GIC observations made at a single power grid transformer near Christchurch in New Zealand, Smith et al. (2022) showed that SCs that occurred while New Zealand was on the dayside of the planet were related to GICs that were 30% larger than if New Zealand were on the night‐side for the same magnetic field rate of change. This could not be accounted for by controlling for the dominant orientation of the largest rate of change of the field, and was inferred to be partly due to the different frequency content of the SC signature at different local times.…”

Section: Introductionmentioning

confidence: 99%

“…In this study, we expand on the work of Smith et al. (2022), assessing how GIC observed at 75 different power grid transformers in the New Zealand power network are impacted by SCs. We determine whether the type of SC is important, if the previous day/night asymmetry is common across the network, and how the dominant orientation of the SC signature impacts distinct part of the system.…”

Section: Introductionmentioning

confidence: 99%

Sudden Commencements and Geomagnetically Induced Currents in New Zealand: Correlations and Dependance

Smith,

Rodger,

Mac Manus

et al. 2024

Space Weather

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Changes in the Earth's geomagnetic field induce geoelectric fields in the solid Earth. These electric fields drive Geomagnetically Induced Currents (GICs) in grounded, conducting infrastructure. These GICs can damage or degrade equipment if they are sufficiently intense—understanding and forecasting them is of critical importance. One of the key magnetospheric phenomena are Sudden Commencements (SCs). To examine the potential impact of SCs we evaluate the correlation between the measured maximum GICs and rate of change of the magnetic field (H′) in 75 power grid transformers across New Zealand between 2001 and 2020. The maximum observed H′ and GIC correlate well, with correlation coefficients (r2) around 0.7. We investigate the gradient of the relationship between H′ and GIC, finding a hot spot close to Dunedin: where a given H′ will drive the largest relative current (0.5 A nT−1 min). We observe strong intralocation variability, with the gradients varying by a factor of two or more at adjacent transformers. We find that GICs are (on average) greater if they are related to: (a) Storm Sudden Commencements (SSCs; 27% larger than Sudden Impulses, SIs); (b) SCs while New Zealand is on the dayside of the Earth (27% larger than the nightside); and (c) SCs with a predominantly East‐West magnetic field change (14% larger than North‐South equivalents). These results are attributed to the geology of New Zealand and the geometry of the power network. We extrapolate to find that transformers near Dunedin would see 2000 A or more during a theoretical extreme SC (H′ = 4000 nT min−1).

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“…Mathie and Mann, 2000;Murphy et al, 2011) and event based studies of Ultra-low Frequency waves (e.g., Rae et al, 2019) which can be used in radiation belt modeling (e.g., Mann et al, 2016;Ozeke et al, 2017;Ma et al, 2018); studies of the spatial distribution and expansion of waves (e.g. Milling et al, 2008;Murphy et al, 2009), field aligned currents (e.g., Pulkkinen et al, 2003;Weygand et al, 2011), the substorm current wedge (e.g., Lester et al, 1983;Cramoysan et al, 1995), and geomagnetically induced currents (e.g., Pulkinen et al, 2005;Pulkinen et al, 2017;Smith et al, 2022); analysis of field line resonances (e.g., Mann et al, 2002;Rae et al, 2005); remote sensing of in-situ plasma properties (e.g., e.g., Mann et al, 2002;Rae et al, 2005); and magnetoseismology of ionospheric disturbances (e.g., Waters et al, 1996;Chi and Russell, 2005;Chi et al, 2013;Kale et al, 2009). For more examples see Mann et al (2008), Russell et al (2008), Menk and Waters (2013), Engebretson and Zesta (2017), and Murphy et al (2022a)).…”

Section: Introductionmentioning

confidence: 99%

GMAG: An open-source python package for ground-based magnetometers

Murphy

Rae

Halford

et al. 2022

Front. Astron. Space Sci.

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Magnetometers are a key component of heliophysics research providing valuable insight into the dynamics of electromagnetic field regimes and their coupling throughout the solar system. On satellites, magnetometers provide detailed observations of the extension of the solar magnetic field into interplanetary space and of planetary environments. At Earth, magnetometers are deployed on the ground in extensive arrays spanning the polar cap, auroral and sub-auroral zone, mid- and low-latitudes and equatorial electrojet with nearly global coverage in azimuth (longitude or magnetic local time—MLT). These multipoint observations are used to diagnose both ionospheric and magnetospheric processes as well as the coupling between the solar wind and these two regimes at a fraction of the cost of in-situ instruments. Despite their utility in research, ground-based magnetometer data can be difficult to use due to a variety of file formats, multiple points of access for the data, and limited software. In this short article we review the Open-Source Python library GMAG which provides rapid access to ground-based magnetometer data from a number of arrays in a Pandas DataFrame, a common data format used throughout scientific research.

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The Correspondence Between Sudden Commencements and Geomagnetically Induced Currents: Insights From New Zealand

Cited by 8 publications

References 72 publications

Solar Cycle and Solar Wind Dependence of the Occurrence of Large dB/dt Events at High Latitudes

Solar Cycle and Solar Wind Dependence of the Occurrence of Large dB/dt Events at High Latitudes

Sudden Commencements and Geomagnetically Induced Currents in New Zealand: Correlations and Dependance

GMAG: An open-source python package for ground-based magnetometers

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