Articles | Volume 22, issue 12
Ann. Geophys., 22, 4243–4258, 2004
Ann. Geophys., 22, 4243–4258, 2004

  22 Dec 2004

22 Dec 2004

Measuring the dayside reconnection rate during an interval of due northward interplanetary magnetic field

G. Chisham1, M. P. Freeman1, I. J. Coleman1, M. Pinnock1, M. R. Hairston2, M. Lester3, and G. Sofko4 G. Chisham et al.
  • 1British Antarctic Survey, Natural Environment Research Council, High Cross, Madingley Road, Cambridge, CB3 0ET, UK
  • 2Center for Space Sciences, The University of Texas at Dallas, Richardson, Texas, USA
  • 3Department of Physics and Astronomy, University of Leicester, Leicester, LE1 7RH, UK
  • 4Institute of Space and Atmospheric Studies, University of Saskatchewan, Saskatoon, Saskatchewan, Canada

Abstract. This study presents, for the first time, detailed spatiotemporal measurements of the reconnection electric field in the Northern Hemisphere ionosphere during an extended interval of northward interplanetary magnetic field. Global convection mapping using the SuperDARN HF radar network provides global estimates of the convection electric field in the northern polar ionosphere. These are combined with measurements of the ionospheric footprint of the reconnection X-line to determine the spatiotemporal variation of the reconnection electric field along the whole X-line. The shape of the spatial variation is stable throughout the interval, although its magnitude does change with time. Consequently, the total reconnection potential along the X-line is temporally variable but its typical magnitude is consistent with the cross-polar cap potential measured by low-altitude satellite overpasses. The reconnection measurements are mapped out from the ionosphere along Tsyganenko model magnetic field lines to determine the most likely reconnection location on the lobe magnetopause. The X-line length on the lobe magnetopause is estimated to be ~6–11 RE in extent, depending on the assumptions made when determining the length of the ionospheric X-line. The reconnection electric field on the lobe magnetopause is estimated to be ~0.2mV/m in the peak reconnection region.

Key words. Space plasma physics (Magnetic reconnection) – Magnetospheric physics (Magnetopause, cusp and boundary layers) – Ionosphere (Plasma convection)