Characteristics of magnetospheric energetics during geomagnetic storms

• Published in: Journal of Geophysical Research: Space Physics Vol. 117; no. A4
• Main Authors: Li, H., Wang, C., Xu, W. Y., Kan, J. R.
• Format: Journal Article
• Language: English
• Published: Washington, DC Blackwell Publishing Ltd 01.04.2012; American Geophysical Union
• Subjects: Atmospheric sciences; Earth sciences; Earth, ocean, space; energy budget; Energy dissipation; Exact sciences and technology; Injection; magnetic storms; Magnetism; magnetospheric energetics; partition of energy dissipation; Storms; Energetics; High latitude; efficiency; Total energy; magnetic storms; surveys; energy balance; recovery; duration; intensity; coupling; energy dissipation; magnetosphere; correlation; Ring current; injection; storms
• ISSN: 0148-0227; 2169-9380; 2156-2202; 2169-9402
• DOI: 10.1029/2012JA017584

To investigate the magnetospheric energetics during magnetic storms, we performed a statistical survey of 307 geomagnetic storms between 1995 and 2009. For the purpose of getting a detailed understanding of the energy processes, we conducted our study of storm‐time energetics for three time durations: the main phase, the recovery phase, and the total storm period. We found that 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. For moderate storms, the high‐latitude ionospheric dissipation is dominant, with only ∼30% energy dissipated via the ring current; whereas for superstorms, the ring current injection becomes dominant, with ∼70% energy dissipated via the ring current. We also confirmed the essential and crucial role of the total energy input into the magnetosphere during the main phase in controlling the storm intensity. The total energy input during the main phase is directly proportional to the storm intensity. Their correlation efficiency is as high as 0.85. The storm‐time energy budget was also quantified in this study. The coupling efficiency indicates an exponential decay as the storm intensity increases, with the coupling efficiency during the main phase less than that during the recovery phase. Key Points Partition of storm‐time energy dissipation is controlled by the storm intensity Proportion of ring current injection is positively correlated to storm intensity Total energy input is directly proportional to the storm intensity