Identification of Vortex Currents in the Ionosphere and Estimation of Their Parameters Based on Ground Magnetic Data
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tification of Vortex Currents in the Ionosphere and Estimation of Their Parameters Based on Ground Magnetic Data V. E. Chinkina, *, A. A. Solovieva, b, and V. A. Pilipenkoa, b a
b
Geophysical Center, Russian Academy of Sciences, Moscow, 119296 Russia Schmidt Institute of Physics of the Earth, Russian Academy of Sciences, Moscow, 123995 Russia *e-mail: [email protected] Received December 3, 2019; revised January 31, 2020; accepted May 21, 2020
Abstract—A system to process data from a 2D network of magnetic stations is proposed for the identification of eddy currents in the ionosphere and the estimation of their parameters. The methodology is applied to an analysis of the structure of daytime traveling convection vortices (TCVs) based on data from Arctic. The problem is solved with optimization methods for various functions obtained via spatial interpolation and subsequent data regularization. The developed approach makes it possible not only to find eddy structures automatically but also to determine the current values of their characteristic parameters: the spatial structure of the field aligned currents (FACs), and the group velocity of the horizontal propagation of the vortex along the ionosphere. DOI: 10.1134/S0016793220050035
1. INTRODUCTION The transfer of electromagnetic-disturbance energy from the Earth’s magnetosphere to the ionosphere occurs mainly due to field aligned currents (FACs), which flow along the lines of force of the magnetosphere magnetic field. At high latitudes, where the geomagnetic field B is almost vertical, a terrestrial magnetic disturbance is created by Hall eddy currents excited by FACs. Depending on the type of magnetospheric disturbance, ionospheric eddy structures can occur on very different scales: from the planetary scale, when they are induced by an interplanetary shock wave (Fujita et al., 2005), to small kinetic scales in auroral structures (Chmyrev et al., 1988). Most of the energy of unsteady magnetospheric–ionospheric disturbances is concentrated in the localized structures associated with eddy currents. These are responsible for geomagnetically induced current bursts in extended power lines (Ngwira et al., 2015; Belakhovsky et al., 2019). Thus, the ability to automatically isolate localized eddy structures and determine their parameters with ground-based magnetometers is an extremely important objective. As a rule, the presence of eddies in the disturbed geomagnetic field is determined visually from the pattern of equivalent ionospheric currents constructed from magnetic data (e.g., Engebretson et al., 2013). The new method proposed in this paper makes is possible to find simultaneous vortex structures in the ionosphere automatic from the data of a 2D network of
ground-based magnetometers and to quantify their characteristic parameters. Convective Hall vortices (traveling convection vortices, TCVs, Glassmeier, 1992) were used to test the method for the identification of vortex structures. Convective vortices in the ionosphere are a wellknown and illustrative manifestati
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