Methodology for time‐domain estimation of storm time geoelectric fields using the 3‐D magnetotelluric response tensors. Issue 7 (19th July 2017)

• Record Type: Journal Article
• Authors: Kelbert, Anna; Balch, Christopher C.; Pulkkinen, Antti; Egbert, Gary D.; Love, Jeffrey J.; Rigler, E. Joshua; Fujii, Ikuko
• Is Part Of: Space weather. Volume 15:Issue 7(2017:Jul.)
• Page Start: 874
• Page End: 894
• Publication Date: 2017-07-19
• Subjects: geoelectric fields -- geomagnetically induced currents -- magnetotelluric impedance -- space weather hazards -- real‐time algorithm -- discrete time impulse response; Space environment -- Periodicals; 551.509992
• DOI: 10.1002/2017SW001594
• Languages: English
• ISSNs: 1542-7390

Abstract

Abstract: Geoelectric fields at the Earth's surface caused by magnetic storms constitute a hazard to the operation of electric power grids and related infrastructure. The ability to estimate these geoelectric fields in close to real time and provide local predictions would better equip the industry to mitigate negative impacts on their operations. Here we report progress toward this goal: development of robust algorithms that convolve a magnetic storm time series with a frequency domain impedance for a realistic three‐dimensional (3‐D) Earth, to estimate the local, storm time geoelectric field. Both frequency domain and time domain approaches are presented and validated against storm time geoelectric field data measured in Japan. The methods are then compared in the context of a real‐time application. Plain Language Summary: Magnetic storms can pose significant risks to critical technology infrastructure such as the electric power grids. Real‐time estimation of geoelectric fields can give the grid operators an opportunity for prompt intervention that would mitigate the long‐term consequences. We develop and validate a method to efficiently and accurately (to within 85–90%) "nowcast" storm time geoelectric fields in close to real time in places where both geomagnetic field data are collected or estimated, and a magnetotelluric impedance has been previously measured. This method can be applied in all regions where magnetotelluric data have been collected, including in the United States, where USArray magnetotelluric data survey is ongoing and by 2018 will cover about two thirds of the country. In this work, we focus on the algorithm development only. Key Points: New methodology to estimate geoelectric fields using 3‐D magnetotelluric impedance is developed and validated Estimates capture 85–90% of the signal for measured geoelectric storm time data in Japan Method can be efficiently applied to "nowcast" local geoelectric fields with a tradeoff between accuracy and a modest prediction delay