Articles | Volume 26, issue 6
Ann. Geophys., 26, 1539–1544, 2008
https://doi.org/10.5194/angeo-26-1539-2008
Ann. Geophys., 26, 1539–1544, 2008
https://doi.org/10.5194/angeo-26-1539-2008

  11 Jun 2008

11 Jun 2008

On the edge of the foreshock: model-data comparisons

D. G. Sibeck1, N. Omidi2, I. Dandouras3, and E. Lucek4 D. G. Sibeck et al.
  • 1Code 674, NASA/GSFC, Greenbelt, MD, USA
  • 2Solana Scientific, Solana Beach, CA, USA
  • 3CESR, Toulouse, France
  • 4Imperial College, London, UK

Abstract. We present the results of a global hybrid code simulation for the solar wind-interaction with the Earth's magnetosphere during an interval of steady radial IMF. The model predicts a foreshock marked by innumerable localized, correlated, and large amplitude, density and magnetic field strength variations, depressed velocities, and enhanced temperatures. The foreshock is bounded by a broad (~0.8 RE) region of enhanced densities, temperatures, and magnetic field strengths that extends far (~8.6 RE) upstream from the bow shock. Flow perturbations within the boundary are directed perpendicular to the boundary, towards the unperturbed solar wind and away from the foreshock. Cluster observations of the ion foreshock and pristine solar wind confirm the predictions of the model. The observations suggest that foreshock cavities, crater-like density and magnetic field strength structures whose cores are filled with suprathermal particles, can be interpreted in terms of transient encounters with the foreshock boundary.

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