Polar Hiss Observed by Isis Satellites
- Joseph R. Kan,
- Thomas A. Potemra,
- Susumu Kokubun and
- Takesi Iijima
Published Online: 19 MAR 2013
Copyright 1991 by the American Geophysical Union.
How to Cite
Ondoh, T. (1991) Polar Hiss Observed by Isis Satellites, in Magnetospheric Substorms (eds J. R. Kan, T. A. Potemra, S. Kokubun and T. Iijima), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM064p0387
- Published Online: 19 MAR 2013
- Published Print: 1 JAN 1991
Print ISBN: 9780875900308
Online ISBN: 9781118663981
- Magnetospheric substorms—Congresses
The polar occurrence map for polar hiss (auroral hiss called hitherto) obtained from ISIS-VLF Syowa data is qualitatively similar to that for the inverted-V electron precipitations obtained from Atmospheric Explorer-D [Hoffman and Lin,1981], especially, concerning the low latitude boundary around invariant latitude 70° and the axial symmetry of the 10–22 hour geomagnetic local time (MLT) meridian. A statistical distribution of polar hiss in geomagnetic quiet conditions (Kp= 0–1) also shows the axial symmetry of the 10–22 hour MLT meridian and the low latitude boundary which is higher than that in various geomagnetic conditions. Thus, the occurrence map of polar hiss is different from the auroral zone which has the axial symmetry of the noon-midnight meridian. So, the auroral hiss called hitherto should be hereafter called by name of the polar hiss. The frequency range of the polar hiss is discussed in terms of whistler mode Cherenkov radiation generated from inverted-V electrons with energy below about 40 keV using realistic electron density distribution of the polar magnetosphere. The whistler mode Cherenkov radiation has an upper limit frequency given by the electron plasma frequency, electron gyrofrequency and electron energy. The frequencies of this radiation are higher when generated at lower altitudes than when generated at higher altitudes on the same field line in the polar magnetosphere. The frequency range of the downgoing polar hiss seems to be explained by the whistler-mode Cherenkov radiation generated from inverted-V electrons at geocentric distances below about 2 Re (earth's radius) along geomagnetic field lines between invariant latitudes of 70° and 77°.