Relationship of the ASY-H index with interplanetary medium parameters and auroral activity in magnetic storm main phases during CIR and ICME events

• Main Authors: Boroyev R.N., Vasiliev M.S.
• Format: Article
• Language: English
• Published: INFRA-M 2020-03-01
• Series: Solar-Terrestrial Physics
• Subjects: magnetic storm; asy-h index; dst index; solar wind; electric field
• Online Access: https://naukaru.ru/en/nauka/article/36815/view

In this study, we examine the relationship of the ASY-H index characterizing the partial ring current intensity with interplanetary medium parameters and auroral activity during the main phase of magnetic storms, induced by the solar wind (SW) of different types. Over the period 1979–2017, 107 magnetic storms driven by CIR and ICME (MC + Ejecta) events have been selected. We consider magnetic storms with Dstmin≤ – 50 nT. The average ASY-H index (ASYaver) during the magnetic storm main phase is shown to increase with increasing SW electric field and southward IMF Bz regardless of SW type. There is no relationship between ASYaver and SW velocity. For the CIR and ICME events, the average AE (AEaver) and Kp (Kp aver) indices have been found to correlate with ASYaver. The highest correlation coefficient between AEaver and ASYaver (r = 0.74) is observed for the magnetic storms generated by CIR events. A closer relationship between Kp aver and ASYaver (r = 0.64) is observed for the magnetic storms induced by ICME events. The ASYaver variations correlate with Dstmin. The relationship between ASYaver and the rate of storm development is weak.