Development and Energetics of Geomagnetic Storms Driven by the Solar Wind

Abstract:

Geomagnetic storm is a major geomagnetic disturbance with a global depression of the magnetic field observed in low-latitude and mid-latitude. Based on a statistical survey, we will show some results of its development and energetics, and the impacts from the solar wind. When IMF turns southward, the ring current increases very fast, about 6-10 minutes later. And the ring current enhancement is not symmetric, with a peak near the dusk, revealing the importance of the partial ring current during magnetic storm processes. The location, evolution, and quantitative contribution of the partial ring current are all further obtained. The partial ring current forms in the early main phase, increases gradually until the SYMH index reaches its minimum, and then quickly decreases in the recovery phase. Its contribution weakens gradually as the storm intensity increases. The storm-time energetics is conducted for three time durations: the main phase, the recovery phase, and the total storm period. The partition of the energy dissipation via the ring current injection and high-latitude ionospheric dissipation is controlled by the storm intensity. The proportion of the ring current injection increases linearly as the storm intensity increases for all three time durations. The storm intensity is linearly controlled by the dayside solar wind E-field and the total energy input into the magnetosphere during the main phase.