Open AccessEquatorial auroral records reveal dynamics of the paleo-West Pacific geomagnetic anomaly
Author(s) -
Fei He,
Yong Wei,
Stefano Maffei,
Philip W. Livermore,
Christopher J. Davies,
J. E. Mound,
Kaihua Xu,
Shenshen Cai,
Rixiang Zhu
Publication year - 2021
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.2026080118
Subject(s) - earth's magnetic field , anomaly (physics) , paleomagnetism , geology , south atlantic anomaly , geophysics , magnetic anomaly , geomagnetic secular variation , magnetic field , physics , magnetosphere , geomagnetic storm , van allen radiation belt , quantum mechanics , condensed matter physics
Localized regions of low geomagnetic intensity such as the South Atlantic Anomaly allow energetic particles from the Van Allen radiation belt to precipitate into the atmosphere and have been linked to a signature in the form of red aurora-like airglow visible to the naked eye. Smoothed global geomagnetic models predict a low-intensity West Pacific Anomaly (WPA) during the sixteenth to nineteenth centuries characterized by a simple time dependence. Here, we link the WPA to an independent database of equatorial aurorae recorded in Seoul, South Korea. These records show a complex fluctuating behavior in auroral frequency, whose overall trend from 1500 to 1800 AD is consistent with the locally weak geomagnetic field of the WPA, with a minimum at 1650 AD. We propose that the fluctuations in auroral frequency are caused by corresponding and hitherto unknown fluctuations in the regional magnetic intensity with peaks at 1590 and 1720 AD, a time dependence that has been masked by the smoothing inherent in regularized global geomagnetic models. A physical core flow model demonstrates that such behavior requires localized time-dependent upwelling flows in the Earth's core, possibly driven by regional lower-mantle anomalies.