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Detailed Reference Information |
Huang, L., Hawkins, J.G. and Lee, L.C. (1990). On the generation of the pulsating aurora by the loss cone driven whistler instability in the equatorial region. Journal of Geophysical Research 95: doi: 10.1029/89JA02857. issn: 0148-0227. |
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Whistler waves are believed to play an important role in the generation of the pulsating aurora. Calculations in the literature show that either a loss cone or a thermal anisotropy in the hot plasma component of the magnetosphere can lead to the generation of incoherent whistler waves. In this paper, we have calculated the characteristics of incoherent whistler mode waves generated along the L=5 geomagnetic field line, and considered the implications for the pulsating aurora if these waves play an important role in the pulsation mechanism. For the loss cone driven whistler instability, the growth rate along the L=5 field line is largest just above the ionosphere where the loss cone angle is also large. However, the total amplification factor is actually much larger near the equator due to the more gradual magnetospheric variations and the smaller group velocity in this region. Thus, the largest wave growth from this process is expected in the same location where pitch angle scattering is believed to occur during auroral pulsations. The peak growth rate at the equator occurs at approximately 100 Hz, corresponding to ~1% of the local electron cyclotron frequency. This frequency is much smaller than the peak growth rate frequency at altitudes nearer to the ionosphere on the L=5 field line. It is also in contrast to the frequently stated assumption that the whistler instability results in wave generation near the electron cyclotron frequency. Consequently, if the loss cone driven whistler instability plays an important role in the pulsation mechanism of the pulsating aurora, then the present calculations imply that pulsating whistler emissions in the frequency range of 50 to 150 Hz should be observed near the equator along auroral field lines. ¿ American Geophysical Union 1990 |
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Abstract |
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Keywords
Ionosphere, Equatorial ionosphere, Ionosphere, Auroral ionosphere |
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Publisher
American Geophysical Union 2000 Florida Avenue N.W. Washington, D.C. 20009-1277 USA 1-202-462-6900 1-202-328-0566 service@agu.org |
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