ENERGETIC EVALUATION OF THE LARGEST GEOMAGNETIC STORMS OF SOLAR CYCLE 24 ON MARCH 17, 2015 AND SEPTEMBER 8, 2017 DURING SOLAR MAXIMUM AND MINIMUM, RESPECTIVELY

Some of the most powerful Earth's directed coronal mass ejections (CMEs) from the current 24 solar cycle have been investigated. These are CMEs on March 15, 2015 and on September 4 and 6, 2017. As a result of these impacts of Sun on Earth, the highest intensity of the geomagnetic storms for the 24th solar cycle is observed. These G4 - Severe geomagnetic storms are in the periods March 17-19, 2015 and September 7-10, 2017. We use the solar wind parameters (velocity V, density or concentration N, temperature T-p and intensity of the magnetic field B) from measurements by WIND, ACE and SOHO space crafts in the Lagrange equilibrium point L1 between Sun and Earth. We make calculations for the kinetic (dynamic) energy density E-k, thermal energy density E-t and magnetic energy density E-m during the investigated periods May 10-24, 2015 and September 2-16, 2017. Both the energy densities for the individual events and the cumulative energy for each of them are evaluated. The quantitative analysis shows that not always the size of the geomagnetic reaction is commensurate with the density of the energy flux reaching the magnetosphere. In both studied periods, the energy densities have different behaviour over time. But for both periods, we can talk about the prognostic effect - with varying degrees of increase of the dynamic and thermal energies. Such an effect is not observed in the density of magnetic energy. An inverse relationship between the magnitude of the density of energies and the effect of Forbush decrease of the galactic cosmic rays is established.