A statistical study of hot flow anomalies using Cluster data

G. Facskó, K. Kecskeméty, G. Erdos, M. Tátrallyay, P. W. Daly, I. Dandouras

Research output: Contribution to journalArticle

29 Citations (Scopus)


Hot flow anomalies (HFAs) are studied using observations of the RAPID suprathermal charged particle detector, the FGM magnetometer, and the CIS plasma detector aboard the four Cluster spacecraft. Previously, we studied several specific features of tangential discontinuities on the basis of Cluster measurements in February-April 2003. In this paper, we confirm the following results: the angle between the Sun direction and the tangentional discontinuity (TD) normal is larger than 45° during HFAs, the magnetic field directional change is large. We then present evidence for a new necessary condition for the formation of HFAs, that is, the solar wind speed is significantly (about200 km / s or Δ M f = 2.3 ) higher than the long-term average. The existence of this condition is also confirmed by simultaneous ACE MAG and SWEPAM solar wind observations at the L1 point 1.4 million km upstream of the Earth. The results are compared with recent hybrid simulations.

Original languageEnglish
Pages (from-to)1286-1291
Number of pages6
JournalAdvances in Space Research
Issue number8
Publication statusPublished - 2008


  • Earth's bow-shock
  • Hot flow anomaly
  • Solar wind
  • Tangential discontinuity

ASJC Scopus subject areas

  • Aerospace Engineering
  • Astronomy and Astrophysics
  • Geophysics
  • Atmospheric Science
  • Space and Planetary Science
  • Earth and Planetary Sciences(all)

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