Parameters influencing the growth and decay of the regular part of the AE index

The statistical behavior of the AE index, which describes the intensity of auroral electrojets, has been studied using hourly data. It has been shown that the AE index depends on the solar wind parameters as well as on its own value in the preceding hour. This makes it possible to describe the AE index behavior by the first-order inhomogeneous differential equation. The index growth rate is proportional mainly to the southward component of the interplanetary magnetic field (IMF). The timescale of the breakup of the currents responsible for the index is approximately 2 h. A similarity in the time variations in the AE and Dst indices has been referred to. The empirical formulas, which make it possible to restore the missing values of the IMF southward component from the available AE or Dst indices, have been proposed.