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Ann. Geophys., 24, 2227-2242, 2006
www.ann-geophys.net/24/2227/2006/
© European Geosciences Union 2006
Dayside flow bursts and high-latitude reconnection when the IMF is strongly northward
H. Hu1,2, T. K. Yeoman2, M. Lester2, R. Liu1, H. Yang1, and A. Grocott2
1Polar Research Institute of China, Shanghai, China
2Department of Physics and Astronomy, University of Leicester, Leicester, UK
Abstract. The characteristics of dayside ionospheric convection are
studied using Northern Hemispheric SuperDARN data and DMSP particle and flow
observations when the interplanetary magnetic field (IMF) was strongly
northward during 13:00–15:00 UT on 2 March 2002. Although IMF Bx was
positive, which is believed to favour Southern Hemisphere high-latitude
reconnection at equinox, a four-cell convection pattern was observed and
lasted for more than 1.5 h in the Northern Hemisphere. The reconnection
rate derived from an analysis of the Northern Hemisphere SuperDARN data
illustrates that the high-latitude reconnection was quasi-periodic, with a
period between 4–16 min. A sawtooth-like and reverse-dispersed ion signature
was observed by DMSP-F14 in the sunward cusp convection at around 14:41 UT,
confirming that the high-latitude reconnection was pulsed. Accompanying the
pulsed reconnection, strong antisunward ionospheric flow bursts were
observed in the post-noon LLBL region on closed field lines, propagating with
the same speed as the plasma convection. DMSP flow data show that a similar
flow pattern and particle precipitation occurred in the conjugate Southern Hemisphere.
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