| Autor: |
Kellerman, Adam C., Mcgranaghan, Ryan, Bortnik, Jacob, Carter, Brett A., Hughes, Joseph, Arritt, Robert F., Venkataramani, Karthik, Perry, Charles H., McCormick, Jackson, Ngwira, Chigomezyo M., Cohen, Morris, Yue, Jia |
| Předmět: |
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| Zdroj: |
Space Weather: The International Journal of Research & Applications; Feb2022, Vol. 20 Issue 2, p1-13, 13p |
| Abstrakt: |
Geomagnetically induced currents (GICs) at middle latitudes have received increased attention after reported power grid disruptions due to geomagnetic disturbances. However, quantifying the risk to the electric power grid at middle latitudes is difficult without understanding how the GIC sensors respond to geomagnetic activity on a daily basis. Therefore, in this study the question "Do measured GICs have distinguishable and quantifiable long‐period and short‐period characteristics?" is addressed. The study focuses on the long‐term variability of measured GIC, and establishes the extent to which the variability relates to quiet‐time geomagnetic activity. GIC quiet‐day curves (QDCs) are computed from measured data for each GIC node, covering all four seasons, and then compared with the seasonal variability of thermosphere‐ionosphere‐electrodynamics general circulation model (TIE‐GCM)‐simulated neutral wind and height‐integrated current density. The results show strong evidence that the middle‐latitude nodes routinely respond to the tidal‐driven Sq variation, with a local time and seasonal dependence on the direction of the ionospheric currents, which is specific to each node. The strong dependence of GICs on the Sq currents demonstrates that the GIC QDCs may be employed as a robust baseline from which to quantify the significance of GICs during geomagnetically active times and to isolate those variations to study independently. The QDC‐based significance score computed in this study provides power utilities with a node‐specific measure of the geomagnetic significance of a given GIC observation. Finally, this study shows that the power grid acts as a giant sensor that may detect ionospheric current systems. Plain Language Summary: Changes in the activity of our star, the Sun, can lead to currents flowing through the power grid (known as geomagnetically induced currents, or GICs) at middle latitudes, potentially causing disruptions to our daily lives. In this study, the question "Do measured GICs have patterns over the course of a day, and over different seasons that can be easily identified?" is answered. The study focuses on times when the Sun is quiet, and connects the observed GICs to changes in the upper atmosphere. The results show that indeed, there is a signal in the GICs, which can be connected to atmospheric changes. The study provides a new method which can help power grid operators understand (a) the performance of their current GIC monitors, and (b) whether or not a measured change in current is due to activity driven by the Sun. Key Points: Variability in quiet‐time geomagnetically induced currents (GICs) at middle latitudes follows a semidiurnal and annual cycleMiddle‐latitude GIC observations are sensitive to quiet‐time magnetic perturbations associated with the Sq currentGIC quiet‐day curves provide a robust baseline for significance analysis of GICs during geomagnetically disturbed times [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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