Dependence of geomagnetic activity during magnetic storms on solar-wind parameters for different types of streams: 4. Simulation for magnetic clouds

In this work, we confirm the possibility of approximating the main phase of a magnetic storm (Dst ≤ −50 nT) caused by magnetic clouds (MCs) with a linear dependence on solar-wind parameters, which are integral electric field sumEy, dynamic pressure Pd, and level of field fluctuations σB. The results show that the main phase of magnetic storm induced by MC is described best by a model with individual values of the main phase approximation coefficients: the correlation coefficient between the measured and model Dst values is 0.99, and the rms deviation is 2.6 nT. The model version with coefficients averaged over all storms describes the main phase much more poorly: the correlation coefficient is 0.65, and the rms deviation is 21.7 nT. A more precise version of the model of the storm main phase induced by MC was developed after introducing corrections that takes into account the history of development of onset of the magnetic-storm main phase: the correlation coefficient is 0.83, and the rms deviation is 15.6 nT. The Dst prediction results during the main phase using the technique suggested are shown for individual magnetic storms as examples.