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JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 112, A06201, doi:10.1029/2006JA012141, 2007

Dayside reconnection enhancement resulting from a solar wind dynamic pressure increase

A. Boudouridis

Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, Los Angeles, California, USA


L. R. Lyons

Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, Los Angeles, California, USA


E. Zesta

Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, Los Angeles, California, USA


J. M. Ruohoniemi

Applied Physics Laboratory, Johns Hopkins University, Laurel, Maryland, USA


Abstract

It is well known that the Interplanetary Magnetic Field (IMF) is the major contributor to geomagnetic activity on Earth. Recent studies, however, have shown that solar wind dynamic pressure variations also cause global effects when they encounter the terrestrial magnetosphere. In particular, it has been shown that solar wind dynamic pressure enhancements significantly increase particle precipitation and cause global intensification of the aurora. Further studies using Defense Meteorological Satellite Program (DMSP) measurements have demonstrated that solar wind pressure increases also significantly affect the size of the polar cap and the cross-polar cap potential drop. This implies that the dynamic pressure has an important effect on the coupling efficiency between the solar wind and the Earth’s magnetosphere, which is in addition to that due to the IMF. It was previously suggested, on the basis of the DMSP data, that solar wind dynamic pressure enhancements induce enhanced magnetotail reconnection and magnetospheric convection. We now present Super Dual Auroral Radar Network (SuperDARN) observations for a number of events that demonstrate significantly enhanced ionospheric convection in the dayside ionosphere associated with the impact of solar wind pressure fronts. The enhanced convection extends to the vicinity of the expected location of the dayside separatrix, suggesting that the solar wind dynamic pressure strongly affects dayside reconnection as well as polar-cap convection.

Received 1 November 2006; accepted 7 March 2007; published 2 June 2007.

Keywords: Solar wind dynamic pressure; ionospheric convection; reconnection.

Index Terms: 2784 Magnetospheric Physics: Solar wind/magnetosphere interactions; 2723 Magnetospheric Physics: Magnetic reconnection (7526, 7835); 2776 Magnetospheric Physics: Polar cap phenomena; 2760 Magnetospheric Physics: Plasma convection (2463); 2712 Magnetospheric Physics: Electric fields (2411).

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Citation: Boudouridis, A., L. R. Lyons, E. Zesta, and J. M. Ruohoniemi (2007), Dayside reconnection enhancement resulting from a solar wind dynamic pressure increase, J. Geophys. Res., 112, A06201, doi:10.1029/2006JA012141.