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The Distant Magnetotail Under Long Duration, Very Northward IMF Conditions: October 22-24, 2003A unique 32 hour interval of very northward Interplanetary Magnetic Field (IMF) on October 22-24, 2003 created a exceptionally thick cold dense magnetotail plasma sheet, a small polar cap and accompanying small tail lobe. These features were detected by the Cluster DMSP and FAST spacecraft and modeled by a global simulation as described in papers by Oieroset et al. (2005) and Li et al. (2005). During the same interval the Wind spacecraft was passing through the center of the magnetotail about 130 Re downstream of Earth. Wind results will be described that reveal a very unusual magnetotail characterized by (1) continual tailward flow of 200-400 km/s with densities in the range 0.2-3/cc, both of whch are clearly less than those expected in the magnetosheath, (2) a mostly northward Bz but with a predominant Bx field component with sign reversals indicating crossings between the two hemispheres of the tail, and (3) velocity waves superposed on the downstream flow with peak-to-peak amplitudes of 100 to 200 km/s, periods of 10 to 20 minutes and clockwise polarization. Low altitude DMSP and Fast measurements reveal an auroral oval with enhanced latitudinal thickness and a small polar cap filled with structured precipitzting electrons and few ions. A new global MHD simulation of the event exhibits a highly elliptical tail of diminished cross-section at 130 Re with major axis aligned with the northward IMF. The tail current sheet also tends to be aligned in a north-south direction with the two tail hemispheres to the east and west with their polarities depending on prior history of the IMF. The simulation appears to be consistent with many, but not all, of the observations. High latitude cusp reconnection and subsequent downtail flow of closed field lines may explain the tail structure, but the waves are more likely due to the Kelvin-Helmholtz instability often thought to occur during northward IMF conditions.
Document ID
20070018239
Acquisition Source
Goddard Space Flight Center
Document Type
Conference Paper
Authors
Fairfield, Donald H.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Oieroset, M.
(California Univ. Berkeley, CA, United States)
Raeder, J.
(New Hampshire Univ. Durham, NH, United States)
Lepping, R. P.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Newell, P. T.
(Johns Hopkins Univ. Laurel, MD, United States)
Wind, S.
(Johns Hopkins Univ. Laurel, MD, United States)
Date Acquired
August 23, 2013
Publication Date
January 1, 2006
Subject Category
Geophysics
Meeting Information
Meeting: 2006 AGU Fall Meeting
Location: San Francisco, CA
Country: United States
Start Date: December 11, 2006
End Date: December 15, 2006
Sponsors: American Geophysical Union
Distribution Limits
Public
Copyright
Other

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