Reconnection driven lobe convection: Interball tail probe observations and global simulations |
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| Affiliation: | 1. Institute of Geophysics and Planetary Physics, University of California, 405 Hilgard Avenue, Los Angeles, CA 90095-1567, USA;2. Space Research Institute, Russian Academy of Sciences, Moscow, Russia;1. Tree Ring Laboratory, Lamont Doherty Earth Observatory of Columbia University, Palisades, NY, 10964, USA;2. Department of Earth and Environmental Science, Columbia University, New York, NY, 10027, USA;3. NASA Goddard Institute for Space Studies, New York, NY, 10025, USA;4. Ocean & Climate Physics, Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY, 10964, USA;5. Department of Geography and Development and Laboratory of Tree Ring Research, University of Arizona, Tucson, AZ, 85721, USA;6. Department of Geography, University of Cambridge, Cambridge, CB2 3EN, UK;7. Department of Physical Geography, Stockholm University, Stockholm, 106-91, Sweden;1. Istituto Nazionale di Geofisica e Vulcanologia, Via di Vigna Murata 605, 00143 Rome, Italy;2. DISIM, University of L’Aquila, via Vetoio 1, 67100 L’Aquila, Italy;3. University of Oslo, Problemveien 7, 0315 Oslo, Norway;4. Space Environment and Radio Engineering Group (SERENE), University of Birmingham, B15 2TT Birmingham, UK;5. SpacEarth Technology, Via di Vigna Murata, 00143 Rome, Italy;6. Institute of Atmospheric Physics of the Czech Academy of Sciences, Boční II 1401, 14100 Prague, Czech Republic;7. Istituto di Astrofisica e Planetologia Spaziali, INAF, Via del Fosso del Cavaliere 100, 00133 Rome, Italy;1. New Mexico Consortium, Los Alamos, NM, USA;2. NASA Goddard Space Flight Center, Greenbelt, MD, USA;3. Department of Physics, Lancaster University, UK;4. JHU Applied Physics Laboratory, Laurel, MD, USA;5. NOAA Space Weather Prediction Center, Boulder, CO, USA |
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| Abstract: | We present Interball Tail Probe observations from the high latitude mid-tail magnetopause which provide evidence of reconnection between the interplanetary magnetic field (IMF) and lobe field lines during a 6 h interval of stable northward and dawnward IMF on October 19, 1995. Results from a global magnetohydrodynamic simulation for this interval compare well with the Interball observations. With the simulations, we provide an extended global view of this event which gives us insight into the reconnection and convection dynamics of the magnetosphere. We find that reconnection occurs in a region of limited spatial extent near the terminator and where the IMF and the lobe field are anti-parallel. Reconnected IMF field lines drape over the dayside magnetosphere, convect along the flanks into the nightside, and enter the magnetotail through a small entry window that is located in the flank opposite to the reconnection site. Ionospheric convection is consistent with previous observations under similar IMF conditions and exhibits a two cell pattern with a dominant lobe cell over the pole. The magnetic mapping between the ionosphere and the lobe boundary is characterized by two singularities: the narrow entry window in the tail maps to a 6 h wide section of the ionospheric lobe cell. A singular mapping line cuts the lobe cell open and maps to almost the entire tail magnetopause. By this singularity the magnetosphere avoids having a stagnation point, i.e., the lobe cell center maps to a tailward convecting field line. The existence of singularities in the magnetic mapping between the ionosphere and the tail has important implications for the study of tail–ionosphere coupling via empirical magnetic field models. Because the lobe–IMF reconnection cuts away old lobe flux and replaces it with flux tubes of magnetosheath origin, solar wind plasma enters the lobes in a process that is similar to the one that operates during southward IMF. |
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