University of Oulu

Vanhamäki, H., Maute, A., Alken, P. et al. Dipolar elementary current systems for ionospheric current reconstruction at low and middle latitudes. Earth Planets Space 72, 146 (2020).

Dipolar elementary current systems for ionospheric current reconstruction at low and middle latitudes

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Author: Vanhamäki, Heikki1; Maute, Astrid2; Alken, Patrick3;
Organizations: 1Ionospheric Research Unit, University of Oulu, Oulu, Finland
2High Altitude Observatory, National Center for Atmospheric Research, Boulder, Colorado, USA
3Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado, USA
4Department of Earth and Planetary Sciences, Kyushu University, Fukuoka, Japan
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 1.9 MB)
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Language: English
Published: Springer Nature, 2020
Publish Date: 2020-11-17


The technique of spherical elementary current systems (SECS) is a powerful way to determine ionospheric and field-aligned currents (FAC) from magnetic field measurements made by low-Earth-orbiting satellites, possibly in combination with magnetometer arrays on the ground. The SECS method consists of two sets of basis functions for the ionospheric currents: divergence-free (DF) and curl-free (CF) components, which produce poloidal and toroidal magnetic fields, respectively. The original CF SECS are only applicable at high latitudes, as they build on the assumption that the FAC flow radially into or out of the ionosphere. The FAC at low and middle latitudes are far from radial, which renders the method inapplicable at these latitudes. In this study, we modify the original CF SECS by including FAC that flow along dipolar field lines. This allows the method to be applied at all latitudes. We name this method dipolar elementary current systems (DECS). Application of the DECS to synthetic data, as well as Swarm satellite measurements are carried out, demonstrating the good performance of this method, and its applicability to studies of ionospheric current systems at low and middle latitudes.

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Series: Earth, planets and space
ISSN: 1343-8832
ISSN-E: 1880-5981
ISSN-L: 1343-8832
Volume: 72
Article number: 146
DOI: 10.1186/s40623-020-01284-1
Type of Publication: A1 Journal article – refereed
Field of Science: 115 Astronomy and space science
Funding: This work was conducted under a contract with the European Space Agency (ESA; ESRIN contract 4000118382/16/I-EF). The work of HV was supported by the Academy of Finland project 314664. AM was supported by by NASA grant NNX16AK88G. HL acknowledges support by JSPS KAKENHI grants 18H01270, 18H04446, 17KK0095, and JSPS-DFG bilateral grant.
Academy of Finland Grant Number: 314664
Detailed Information: 314664 (Academy of Finland Funding decision)
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