Substorm‐Ring Current Coupling:A Comparison of Isolated and Compound Substorms

Sandhu, J. K. and Rae, I.J. and Freeman, M.P. and Gkioulidou, M. and Forsyth, C. and Reeves, G. D. and Murphy, K. R. and Walach, Maria (2019) Substorm‐Ring Current Coupling:A Comparison of Isolated and Compound Substorms. Journal of Geophysical Research: Space Physics, 124 (8). pp. 6776-6791. ISSN 2169-9402

[thumbnail of 851553_1_merged_1561735871_final]
Text (851553_1_merged_1561735871_final)
851553_1_merged_1561735871_final.pdf - Accepted Version
Available under License Creative Commons Attribution-NonCommercial.

Download (6MB)


Substorms are a highly variable process, which can occur as an isolated event or as part of a sequence of multiple substorms (compound substorms). In this study we identify how the low‐energy population of the ring current and subsequent energization varies for isolated substorms compared to the first substorm of a compound event. Using observations of H+ and O+ ions (1 eV to 50 keV) from the Helium Oxygen Proton Electron instrument onboard Van Allen Probe A, we determine the energy content of the ring current in L‐MLT space. We observe that the ring current energy content is significantly enhanced during compound substorms as compared to isolated substorms by ∼20–30%. Furthermore, we observe a significantly larger magnitude of energization (by ∼40–50%) following the onset of compound substorms relative to isolated substorms. Analysis suggests that the differences predominantly arise due to a sustained enhancement in dayside driving associated with compound substorms compared to isolated substorms. The strong solar wind driving prior to onset results in important differences in the time history of the magnetosphere, generating significantly different ring current conditions and responses to substorms. The observations reveal information about the substorm injected population and the transport of the plasma in the inner magnetosphere.

Item Type:
Journal Article
Journal or Publication Title:
Journal of Geophysical Research: Space Physics
Additional Information:
An edited version of this paper was published by AGU. Copyright 2019 American Geophysical Union. Sandhu, J. K., Rae, I. J., Freeman, M. P., Gkioulidou, M., Forsyth, C., Reeves, G. D., et al. ( 2019). Substorm‐ring current coupling: A comparison of isolated and compound substorms. Journal of Geophysical Research: Space Physics, 124. To view the published open abstract, go to and enter the DOI.
ID Code:
Deposited By:
Deposited On:
27 Aug 2019 13:15
Last Modified:
27 Sep 2023 00:21