Articles | Volume 26, issue 8
Ann. Geophys., 26, 2449–2458, 2008
https://doi.org/10.5194/angeo-26-2449-2008

Special issue: STAMMS: Spatio-Temporal Analysis and Multipoint Measurements...

Ann. Geophys., 26, 2449–2458, 2008
https://doi.org/10.5194/angeo-26-2449-2008

  13 Aug 2008

13 Aug 2008

Momentum transfer at the high-latitude magnetopause and boundary layers

E. J. Lund1, C. J. Farrugia1, and P. E. Sandholt2 E. J. Lund et al.
  • 1Space Science Center, University of New Hampshire, Durham, New Hampshire, USA
  • 2Department of Physics, University of Oslo, Oslo, Norway

Abstract. How and where momentum is transferred from the solar wind to the magnetosphere and ionosphere is one of the key problems of space physics. Much of this transfer occurs through direct reconnection on the dayside, particularly when the IMF is southward. However, momentum transfer also occurs at higher latitudes via Alfvén waves on old open field lines, even for southward IMF. This momentum is transferred to the ionosphere via field-aligned currents (FACs), and the flow channel associated with these FACs produces a Hall current which causes magnetic variations at high latitude (the Svalgaard-Mansurov effect). We show examples where such momentum transfer is observed with multiple spacecraft and ground-based instruments.