Solar Quiet (Sq) Ionospheric Current Computation during Solar Eclipses: MATLAB Implementation Using Spherical Harmonic Analysis

This work presents a MATLAB-based implementation for computing solar quiet (Sq) ionospheric currents during solar eclipses using the Spherical Harmonic Analysis (SHA) technique. The method decomposes ground-based geomagnetic field variations into equivalent current systems to quantify eclipse-induced perturbations in the Sq current vortices. It supports analysis of multi-station magnetometer data and captures both hemispheric and diurnal current responses with improved temporal and spatial resolution. The implementation facilitates reproducible studies of ionospheric electrodynamics and space-weather effects during solar eclipses.