Evaluation of the Solar Quiet Reference Field (SQRF) Model for Space Weather Applications in the South America Magnetic Anomaly

Abstract

In the present work, we evaluate the accuracy of the Solar Quiet Reference Field (SQRF) model for estimating and predicting the geomagnetic solar quiet (Sq) daily field variation in the South America Magnetic Anomaly (SAMA) region. This model is based on the data set of fluxgate magnetometers from 12 magnetic stations of the Embrace Magnetometer Network (Embrace MagNet) from 2010 to 2018. The model predicts the monthly average horizontal field of the geomagnetic quiet (Sq-H) daily variation solving a set of equations for the specified geographic coordinates in terms of the solar cycle activity, the day of the year, and the universal time. We carried out two comparisons between the prediction and observational data of the Sq-H field. The first part attempts to evaluate the accuracy for estimating the Sq-H field over Medianeira (25.30°S, 54.11°W, dip angle: -33.45°) by using linear interpolation on the SQRF coefficients. The second part of the analysis attempts to evaluate the accuracy for predicting the quiet daily field variation over Cachoeira Paulista (22.70°S, 45.01°W, dip angle: -38.48°). The results of the prediction for both locations show that this empirical model presents a good agreement with the Sq-H field obtained from the magnetic field data. The accuracy of the SQRF model (high correlation, r >0.9) provides a high potential for estimating and predicting geomagnetic quiet daily field variation for space weather applications.

Ionospheric Current Variations by Empirical Orthogonal Function Analysis: Solar Activity Dependence and Longitudinal Differences

“…Earlier studies based on various observations and modeling techniques, particularly those pertaining to empirical curve fitting of Sq current variation have been conducted (e.g., S. S. Chen et al., 2020, 2021; Vanhamäki et al., 2020; Yamazaki et al., 2009, 2010, 2011). These studies explored the dynamics of the ionosphere and its interaction with the magnetosphere, in particular, examining the consequences of universal time (UT), season and day‐to‐day variations (e.g., S. S. Chen et al., 2021; Kirchhoff & Carpenter, 1976; Pfaff et al., 2020; Schlapp & Butcher, 1995; Yamazaki et al., 2016), including the effects of local neutral winds (e.g., Maute, 2017; Yamazaki et al., 2021). It was remarked that due to variations in the ionospheric conductivity and neutral winds, the Sq current system exhibits hemispheric asymmetry, with its strength in the summer hemisphere being greater than that in the winter hemisphere.…”