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JOURNAL OF GEOPHYSICAL RESEARCH,
VOL. 114,
A11306,
14 PP., 2009
doi:10.1029/2009JA014281
Evidence that solar wind fluctuations substantially affect global convection and substorm occurrence
Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, California, USA
Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, California, USA
Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, California, USA
Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, California, USA
Department of Astronomy and Space Science, Chungbuk National University, Cheongju, South Korea
Center for Geospace Studies, SRI International, Menlo Park, California, USA
Center for Geospace Studies, SRI International, Menlo Park, California, USA
Department of Earth and Space Sciences, Institute for Geophysics and Planetary Physics, University of California, Los Angeles, California, USA
Space Sciences Laboratory, University of California, Berkeley, California, USA
Space Sciences Laboratory, University of California, Berkeley, California, USA
Space Sciences Laboratory, University of California, Berkeley, California, USA
Institut für Geophysik und Extraterrestrische Physik, Technische Universität Braunschweig, Braunschweig, Germany
We have used examples of Poker Flat and Sondrestrom incoherent-scatter radar observations of flows within the ionospheric mapping of the nightside plasma sheet and of Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft observations within the nightside plasma sheet to investigate whether the features found in the companion paper by Kim et al. (2009) within the dayside polar cap are also seen within the nightside plasma sheet. We find evidence that this is indeed the case: intensified interplanetary ULF fluctuations substantially enhance nightside convection flows and the fluctuations are reflected in the fluctuation power of the nightside flows. Additionally, our observations show evidence for an enhancement of earthward convection within the inner plasma sheet and an increase in plasma pressure within the plasma sheet in association with enhanced interplanetary ULF fluctuations. We have also found evidence that the enhancement in convection and plasma sheet pressure associated with strong interplanetary fluctuations may lead to a dramatic increase in substorm occurrence under northward interplanetary magnetic field conditions. More detailed testing of the above results is needed. However, if corroborated, it would indicate that interplanetary ULF fluctuations have a substantial effect on global convection and are an important contributor to the large-scale transfer of solar wind energy to the magnetosphere-ionosphere system, to plasma sheet structure and dynamics, and to the occurrence of disturbances such as substorms.
Received 23 March 2009; accepted 5 August 2009; published 10 November 2009.
Citation: (2009), Evidence that solar wind fluctuations substantially affect global convection and substorm occurrence, J. Geophys. Res., 114, A11306, doi:10.1029/2009JA014281.
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