Open AccessEmpirical Modeling of Ionospheric Current Using Empirical Orthogonal Function Analysis and Artificial Neural Network
Author(s) -
Owolabi Charles,
Ruan Haibing,
Yamazaki Yosuke,
Li Jinfeng,
Zhong Jiahao,
Eyelade A. V.,
Priyadarshi Shishir,
Yoshikawa Akimasa
Publication year - 2021
Publication title -
space weather
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.254
H-Index - 56
ISSN - 1542-7390
DOI - 10.1029/2021sw002831
Subject(s) - empirical orthogonal functions , earth's magnetic field , mean squared error , empirical modelling , current (fluid) , artificial neural network , quiet , intensity (physics) , mode (computer interface) , ionosphere , meteorology , mathematics , environmental science , statistics , computer science , geology , geophysics , physics , magnetic field , optics , oceanography , quantum mechanics , machine learning , operating system , programming language
Given the potential importance of solar quiet (Sq) ionospheric current in geomagnetic field modeling, it is vital to obtain accurate parameters characterizing its variations, particularly the spatial and temporal variations. In this paper, we derived the Sq current function based on the spherical harmonic analysis (SHA) technique using a 14‐year (2006–2019) quiet geomagnetic field record over the American sector. The empirical orthogonal function (EOF) analysis was then applied to deduce temporal and spatial variations of the Sq current. It is observed that the first EOF mode of the Sq current function is dominated by solar activity, while the second and third EOF modes exhibit annual and semiannual variations, respectively. Also, the artificial neural network (ANN) model of Sq current function was constructed to validate the EOF model predictions. While the Sq current intensity predicted by the ANN model is underestimated by 2.83%, the EOF model underpredicted the Sq current intensity by 1.92% relative to the observation. The root mean square error (RMSE) of the EOF model is 0.64 kA. This RMSE is about 79% smaller than that of the ANN model. In addition, both the EOF and ANN models capture the variation of the total Sq current ( J total ) intensity with respect to solar activity. In principle, the EOF model had an optimal performance at nearly 98% accuracy, with the ANN model exhibiting almost the same degree of accuracy, which appears to be a reference point for ionospheric conditions when looking for space weather applications.