Relationship between geomagnetic storm development and the solar wind parameter βстатья
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Дата последнего поиска статьи во внешних источниках: 4 марта 2022 г.
Аннотация:We have analyzed the dynamics of solar wind and interplanetary magnetic field (IMF) parameters during the development of 933 isolated geomagnetic storms, observed over the period from 1964 to 2010. The analysis was carried out using the epoch superposition method at intervals of 48 hrs before and 168 hrs after the moment of Dst minimum. The geomagnetic storms were selected by the type of storm commencement (sudden or gradual) and by intensity (weak, moderate, and strong). The dynamics of the solar wind and IMF parameters was compared with that of the Dst index, which is an indicator of the development of geomagnetic storms. The largest number of storms in the solar activity cycle is shown to occur in the years of minimum average values (close in magnitude to 1) of the solar wind parameter beta (beta is the ratio of plasma pressure to magnetic pressure). We have revealed that the dynamics of the Dst index is similar to that of the beta parameter. The duration of the storm recovery phase follows the characteristic recovery time of the beta parameter. We have found out that during the storm main phase the beta parameter is close to 1, which reflects the maximum turbulence of solar wind plasma fluctuations. In the recovery phase, beta returns to background values beta is approximately 2‒3.5. We assume that the solar wind plasma turbulence, characterized by the beta parameter, can play a significant role in the development of geomagnetic storms.