University of Oulu

Kärhä, O., & Tanskanen, E. I. (2022). Newly digitized data from Scandinavian magnetometer array network shows large regional differences in magnetic environment. Journal of Geophysical Research: Space Physics, 127, e2022JA030311.

Newly digitized data from Scandinavian Magnetometer Array network shows large regional differences in magnetic environment

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Author: Kärhä, O.1; Tanskanen, E. I.1,2
Organizations: 1Sodankylä Geophysical Observatory, University of Oulu, Sodankylä, Finland
2Department of Electronics and Nanoengineering, Aalto University, Espoo, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 7.5 MB)
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Language: English
Published: American Geophysical Union, 2022
Publish Date: 2022-06-10


The International Magnetospheric Study (IMS) took place from 1977 to 1979. An objective was to study the magnetosphere at different heights on the Earth and in space simultaneously. The Scandinavian Magnetometer Array (SMA), where a dense magnetometer array was placed in the northern part of Scandinavia, was part of the IMS. This array extended 1,570 km in north-south and 1,290 km in east-west directions. The SMA-magnetometers contained a camera with 35 mm film and three wire-suspended magnets. These instruments recorded the movement of the magnets optically on the film. The usability of the SMA data has been limited by time-consuming digitization by hand. Thus, most of the recordings has been left nondigitized and unstudied. We have developed a method, named DigiMAG, to digitize the SMA recordings by using a custom-built device. This article presents the high-latitude dynamics of the strongest magnetic storm in 1977 between October 26 and 30. We analyze newly digitized data from Rostadalen (ROS), Evenes (EVE), Ritsemjokk (RIJ), and Kiruna (KIR) stations for the three storm-time substorms on October 26–29, 1977. The results show that in the vicinity of the 65° latitude, the storm-time differences of horizontal magnetic components can exceed 500 nT. During the recovery phase of a substorm, 2.8 nT km⁻¹ difference arises over a distance of 167 km between the H-component time derivatives of ROS and RIJ stations in 3 minutes.

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Series: Journal of geophysical research. Space physics
ISSN: 2169-9380
ISSN-E: 2169-9402
ISSN-L: 2169-9380
Volume: 127
Issue: 5
Article number: e2022JA030311
DOI: 10.1029/2022ja030311
Type of Publication: A1 Journal article – refereed
Field of Science: 114 Physical sciences
115 Astronomy and space science
1171 Geosciences
Funding: This work was supported by ReSoLVE Center of Excellence funded by the Academy of Finland (projects 272157 and 307411); FLEX-EPOS & G-EPOS infrastructures within EPOS and FIN-EPOS (numbers 293488, 311714, and 328778); and Vilho, Yrjö and Kalle Väisälä Foundation of the Finnish Academy of Science and Letters.
Academy of Finland Grant Number: 272157
Detailed Information: 272157 (Academy of Finland Funding decision)
307411 (Academy of Finland Funding decision)
Copyright information: © 2022. The Authors. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.