Local Mapping of Polar Ionospheric Electrodynamics

Laundal, K. M.; Reistad, Jone Peter; Hatch, Spencer; Madelaire, Michael; Walker, Simon James; Hovland, A. Ø.; Ohma, Anders; Merkin, V. G.; Sorathia, Kareem

doi:10.1002/essoar.10510450.1

Cited by 3 publications

(7 citation statements)

References 44 publications

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“…This is likely the reason for the notable deviations seen in the right columns. In the Lompe code (Laundal et al., 2022), there is an option to use space magnetometer data only to constrain FACs, intended for use with satellites at relatively high orbit and/or with relatively imprecise measurements.…”

Section: Resultsmentioning

confidence: 99%

“…A Python module that implements everything that is presented in this paper has been published (Laundal et al., 2022). This code also includes the novel method presented in Section 2.4 to calculate the EUV conductance, which does not lead to infinite gradients at the sunlight terminator.…”

Section: Discussionmentioning

confidence: 99%

“…The Lompe technique, as described in this paper, has been implemented in Python, and the code is available on Zenodo (Laundal et al., 2022). The inversion code includes tools for working with SECS and their magnetic fields, and a module for working with cubed‐sphere grids (Ronchi et al., 1996).…”

Section: Discussionmentioning

confidence: 99%

“…All data that have been used in this study are included in the Lompe code repository (Laundal et al., 2022) as sample data sets. This repository also contains code to reproduce all figures in the paper, except Figure 2.…”

Section: Data Availability Statementmentioning

confidence: 99%

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Local Mapping of Polar Ionospheric Electrodynamics

Laundal¹,

Reistad²,

Hatch³

et al. 2022

JGR Space Physics

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An accurate description of the state of the ionosphere is crucial for understanding the physics of Earth's coupling to space, including many potentially hazardous space weather phenomena. To support this effort, ground networks of magnetometer stations, optical instruments, and radars have been deployed. However, the spatial coverage of such networks is naturally restricted by the distribution of land mass and access to necessary infrastructure. We present a new technique for local mapping of polar ionospheric electrodynamics, for use in regions with high data density, such as Fennoscandia and North America. The technique is based on spherical elementary current systems (SECS), which were originally developed to map ionospheric currents. We expand their use by linking magnetic field perturbations in space and on ground, convection measurements from space and ground, and conductance measurements, via the ionospheric Ohm's law. The result is a technique that is similar to the Assimilative Mapping of Ionospheric Electrodynamics (AMIE) technique, but tailored for regional analyses of arbitrary spatial extent and resolution. We demonstrate our technique on synthetic data, and with real data from three different regions. We also discuss limitations of the technique and potential areas for improvement.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Data Availability Statementmentioning

confidence: 99%

See 2 more Smart Citations

Local Mapping of Polar Ionospheric Electrodynamics

Laundal¹,

Reistad²,

Hatch³

et al. 2022

JGR Space Physics

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“…We can then analyze the ionospheric currents at time scales closer to substorm dynamics. Unlike other studies (Laundal et al., 2022) we will estimate the ionospheric currents based only on the magnetic field data, without further knowledge of the ionospheric state.…”

Section: Discussionmentioning

confidence: 99%

Statistical Temporal Variations in the Auroral Electrojet Estimated With Ground Magnetometers in Fennoscandia

et al. 2023

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The link between the Sun and geomagnetic field disturbances has been reported for a long time. In 1852 Sabine identified a link between the number of sunspots, which is an indicator of solar activity, and geomagnetic field disturbances. He found that during a minimum in the sunspot number we experience a reduction in geomagnetic field disturbances (Cliver & Cliver, 1994). Historical reports have shown that for centuries large scale features on the photosphere have coincided with observations of significant, intense geomagnetic activity in the form of low latitude aurora (Schove, 1983), however the mechanisms behind this were not understood. With the arrival of work by Chapman and Birkeland in the late 19th and early 20th century, the description of the Earth's magnetosphere immersed within the solar wind came into focus. Birkeland's early work introduced a current system, which bears his name, flowing in and out of the polar ionosphere. Despite his initial theories involving a stream of high velocity electrons being emitted from the Sun, he moved to the realization of a neutral solar wind made up of both electrons and positively charged ions (Birkeland, 1908;Chapman & Ferraro, 1931). Although a different current system and theory outlined by Chapman prevailed for some time, with the arrival of space based magnetometers Birkeland's theory proved fruitful as it explained the magnetic field perturbations observed (Zmuda et al., 1966). Chapman and Ferraro's work transformed the field of space physics when they described how magnetic storms are manifested through introduction of the magnetosphere and how it interacts with the solar wind (Chapman & Ferraro, 1931;Siscoe, 2001).

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Statistics of temporal variations in the auroralelectrojets over Fennoscandia

Walker

Laundal

Reistad

et al. 2022

Preprint

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We present the implementation of an improved technique to coherently model the high-latitude ionospheric equivalent current. By using a favourable and fixed selection of 20 ground magnetometers in Fennoscandia, we present a method based on Spherical Elementary Current Systems (SECS) to model the currents coherently during 2000-2020. Due to the north-south extent of the ground stations used, we focus on the model output along the 105 * magnetic meridian. In addition to the fixed data locations and SECS analysis grid, our improvements involve taking into account a priori knowledge of the large-scale current systems to improve the robustness of solving the underdetermined inverse problem. We account for contributions from ground induced currents assuming so-called mirror currents. An advantage of this data set over existing empirical models of ionospheric currents is the 1-min output resolution. High temporal resolution enables investigation of temporal changes in the magnetic field. We present an analysis of statistical properties of where (in magnetic latitude and local time) and at what rate ([?]Br /[?]t) the radial magnetic field component fluctuates. We show that [?]Br /[?]t, which is equivalent to the radial component of the curl of the induced electric field, is dependent on latitude, local time, and solar cycle. Other applications of the presented data set are also highlighted, including investigations of how Ultra Low Frequency oscillations in ground magnetic perturbations vary in space and time.

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Local Mapping of Polar Ionospheric Electrodynamics

Cited by 3 publications

References 44 publications

Local Mapping of Polar Ionospheric Electrodynamics

Local Mapping of Polar Ionospheric Electrodynamics

Statistical Temporal Variations in the Auroral Electrojet Estimated With Ground Magnetometers in Fennoscandia

Statistics of temporal variations in the auroralelectrojets over Fennoscandia

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