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Continuous magnetic reconnection at Earth's magnetopause

Nature volume 426, pages 533–537 (2003)Cite this article

Abstract

The most important process that allows solar-wind plasma to cross the magnetopause and enter Earth's magnetosphere is the merging between solar-wind and terrestrial magnetic fields of opposite sense—magnetic reconnection1. It is at present not known whether reconnection can happen in a continuous fashion or whether it is always intermittent. Solar flares2 and magnetospheric substorms3—two phenomena believed to be initiated by reconnection—are highly burst-like occurrences, raising the possibility that the reconnection process is intrinsically intermittent, storing and releasing magnetic energy in an explosive and uncontrolled manner. Here we show that reconnection at Earth's high-latitude magnetopause is driven directly by the solar wind, and can be continuous and even quasi-steady over an extended period of time. The dayside proton auroral spot in the ionosphere—the remote signature of high-latitude magnetopause reconnection4—is present continuously for many hours. We infer that reconnection is not intrinsically intermittent; its steadiness depends on the way that the process is driven.

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Figure 1: Diagram showing the link between reconnection at the magnetopause and its footprint in the ionosphere.
Figure 2: Snapshots of the proton aurora oval and spot on 18 March 2002 showing the continuous presence of the proton aurora spot.
Figure 3: Continuous presence of dayside proton aurora spot (and implied reconnection) for ∼4 h on 18 March 2002.
Figure 4: Continuous presence of dayside proton aurora spot (and implied reconnection) for ∼9 h on 17/18 September 2000.

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Acknowledgements

We are indebted to the IMAGE team and J. L. Burch for the design and successful operation of the IMAGE mission.

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Authors and Affiliations

  1. Space Sciences Laboratory, University of California, Berkeley, California, 94720-7450, USA

    H. U. Frey, T. D. Phan & S. B. Mende

  2. Lockheed Martin Advanced Technology Center, Palo Alto, California, 94304, USA

    S. A. Fuselier

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  1. H. U. Frey
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  2. T. D. Phan
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  3. S. A. Fuselier
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Correspondence to H. U. Frey.

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Frey, H., Phan, T., Fuselier, S. et al. Continuous magnetic reconnection at Earth's magnetopause. Nature 426, 533–537 (2003). https://doi.org/10.1038/nature02084

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