NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Collections About News Help Login
Back to Results
Cluster Observations of Multiple Dipolarization FrontsWe present Cluster observations of a series of dipolarization fronts (DF 1 to 6) at the central current sheet in Earth's magnetotail. The velocities of fast earthward flow following behind each DF 1-3, are comparable to the Alfven velocity, indicating that the flow bursts might have been generated by bursty reconnection that occurred tailward of the spacecraft. Based on multi-spacecraft timing analysis, DF normals are found to propagate mainly earthward at $160-335$ km/s with a thickness of 900-1500 km, which corresponds to the ion inertial length or gyroradius scale. Each DF is followed by significant fluctuations in the $x$ and $y$ components of the magnetic field whose peaks are found 1-2 minutes after the DF passage. These $(B_{x},B_{y} )$-fluctuations propagate dawnward (mainly) and earthward. Strongly enhanced field-aligned beams are observed coincidently with $(B_{x},B_{y})$ fluctuations, while an enhancement of cross-tail currents is associated with the DFs. From the observed pressure imbalance and flux-tube entropy changes between the two regions separated by the DF, we speculate that interchange instability destabilizes the DFs and causes the deformation of the mid-tail magnetic topology. This process generates significant field-aligned currents, and might power the auroral brightening in the ionosphere. However, this event is neither associated with the main substorm auroral breakup nor the poleward expansion, which might indicate that the observed multiple DFs have been dissipated before they reach the inner plasma sheet boundary.
Document ID
20120002021
Acquisition Source
Goddard Space Flight Center
Document Type
Conference Paper
Authors
Hwang, Kyoung-Joo (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Goldstein, Melvyn L. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Lee, Ensang (Kyunghee Univ. Taejon, Korea, Republic of)
Pickett, Jolene S. (Iowa Univ. Iowa City, IA, United States)
Date Acquired
August 25, 2013
Publication Date
December 4, 2011
Subject Category
Geosciences (General)
Report/Patent Number
SM11D-04
GSFC.ABS.5713.2011
Meeting Information
Meeting: American Geophysical Union 2011 Fall Meeting
Location: San Francisco, CA
Country: United States
Start Date: December 4, 2011
End Date: December 9, 2011
Distribution Limits
Public
Copyright
Public Use Permitted.

Related Records

There are no records associated with this record.
No Preview Available