Reconstruction of the IMF polarity using midlatitude geomagnetic observations in the nineteenth century

• Published in: Journal of geophysical research. Space physics 2016-12, Vol.121 (12), p.11,943-11,951
• Main Authors: Vokhmyanin, M. V., Ponyavin, D. I.
• Format: Article
• Language: English
• Subjects: 19th century; Geomagnetic data; Geomagnetic field; Geomagnetic fields; Geomagnetic observations; geomagnetic variations; Geomagnetism; Grounds; IMF polarity; IMF reconstruction; Interplanetary magnetic field; Interplanetary magnetic fields; Latitude; long term; Magnetic fields; Observatories; Perturbation methods; Polarity; Regression analysis; Stations
• ISSN: 2169-9380; 2169-9402
• DOI: 10.1002/2016JA023138

The interplanetary magnetic field (IMF) By component affects the configuration of field‐aligned currents (FAC) whose geomagnetic response is observed from high to low latitudes. The ground magnetic perturbations induced by FACs are opposite on the dawnside and duskside and depend upon the IMF By polarity. Based on the multilinear regression analysis, we show that this effect is presented at the midlatitude observatories, Niemegk and Arti, in the X and Y components of the geomagnetic field. This allows us to infer the IMF sector structure from the old geomagnetic records made at Ekaterinburg and Potsdam since 1850 and 1890, respectively. Geomagnetic data from various stations provide proxies of the IMF polarity which coincide for the most part of the nineteenth and twentieth centuries. This supports their reliabilities and makes them suitable for studying the large‐scale IMF sector structure in the past. Plain Language Summary The interplanetary space is filled with solar plasma which carries the magnetic field of the solar corona ‐ the outer layer of the solar atmosphere.The first regular observations of the solar wind magnetic field started in the 1960s. In this study we reconstructed the directions of this field since 1850. This was achieved through utilizing of the old ground magnetic measurements made at Potsdam and Ekaterinburg. Our results provide an insight into the evolution of the solar magnetic field over the last 150 years and hence may help to solve the enigma of the solar activity cycle. Key Points The IMF By magnetic effect allows us to reconstruct the IMF polarity using midlatitude magnetic observations We infer the daily IMF polarities in the nineteenth century using the Ekaterinburg and Potsdam geomagnetic observations We verify the IMF polarities in the nineteenth century and find them suitable to study the large‐scale IMF sector structure