Calculation of Induced Electric Field During a Geomagnetic Storm Using Recursive Convolution

The relationship between the changes in the earth´s magnetic field and the induced geoelectric field during a geomagnetic disturbance is a frequency-dependent transfer function that depends on earth resistivity at different depths. Traditionally, this function is calculated in the frequency domain expressed as an impulse function in the time domain using fast Fourier transform (FFT) and convolved with dB/dt in the time domain to estimate the geoelectric field E. This paper proposes the approximation of the transfer function in the frequency domain using rational functions and to carry out the calculation of E from dB/dt using fast recursive convolution methods.