High Time Resolution Observations of Magnetospheric Disturbances During Auroral Activity

Content Provider	Semantic Scholar
Author	Fillingimi, M. O. Parks, George K. Lin, Reng Rong Mccarthy, M. Szabo, Adam
Copyright Year	2003
Abstract	We present high time resolution plasma and magnetic field data from the near-Earth plasma sheet during times of active aurorae. The plasma sheet disturbance associated with the auroral activity is composed of Earthward traveling ions with large mean velocities ( = ∫ v f(v)d 3 v) and large amplitude, high frequency magnetic field fluctuations. The ion can change substantially (by up to 100%) on time scales comparable to the local proton gyroperiod. The magnetic fluctuations lead to large, rapidly varying induced electric fields. Power spectral analysis of the magnetic field data shows a significant amount of wave power present at frequencies up to and greater than the local proton cyclotron frequency. Examination of the three-dimensional ion distribution functions indicates that the distributions are complex and nongyrotropic, with large gradients and anisotropies, and dynamic, with considerable changes in the phase space features within one gyroperiod. These results illustrate that kinetic physics controls the plasma behavior during times of plasma sheet disturbances associated with auroral activity. This conclusion is in contrast to the usual interpretation that the large ion velocity moments observed during plasma sheet disturbances are convective in nature (i.e., bursty bulk flows). Additionally, we show that these kinetic effects are important in the near-Earth plasma sheet over a wide range of geomagnetic activity, from pseudobreakups to substorms. Therefore, we suggest that these kinetic processes operate during all types of geomagnetic disturbances and can occur throughout large regions of the magnetotail during substorms and storms.
Starting Page	45
Ending Page	54
Page Count	10
File Format	PDF HTM / HTML
DOI	10.1029/142GM05
Alternate Webpage(s)	http://sprg.ssl.berkeley.edu/~matt/pubs/fillingim_et_al_2003.pdf
Alternate Webpage(s)	https://doi.org/10.1029/142GM05
Language	English
Access Restriction	Open
Content Type	Text
Resource Type	Article