Distribution and Origin of Plasmaspheric Plasma Waves 

James L. Green, Shing F. Fung, Scott Boardsen, Hugh J. Christian 


Recent analysis of electric and magnetic field wave data showing the
distribution  of plasmaspheric waves is reviewed. These studies find that
equatorial electromagnetic (EM) emissions (~30-330 Hz), plasmaspheric hiss (~330
Hz Ð 3.3 kHz), chorus  (~2 kHz Ð 6 kHz), and VLF transmitters (~10-50 kHz) are
the main types of trapped  waves within the plasmasphere. Observations of the
equatorial EM emissions show  that the most intense region is on or near the
magnetic equator in the afternoon  sector and that during times of negative Bz
(interplanetary magnetic field), the  maximum intensity moves from L values of 3
to less than 2. These observations  are consistent with the origin of this
emission being particle-wave interactions in  or near the magnetic equator in
the outer plasmasphere. Plasmaspheric hiss shows  high intensities at high
latitudes and low altitudes over L values from 2 to 3 in the  early afternoon
sector. Plasmaspheric hiss, through particle-wave interactions,  maintains the
slot region in the radiation belts. The longitudinal distribution of the 
plasmaspheric hiss intensity is similar to the distribution of lightning:
stronger over  continents than over the ocean, stronger in the summer than
winter, and stronger  on the dayside than nightside. A lightning origin for
plasmaspheric hiss is also supported by the similarities in the latitudinal
distribution of hiss with that of ground  transmitters and the quiet-time
electron slot region located at slightly higher L (~3)  during solar maximum
than at solar minimum (L~2.5). 

_______________
Inner Magnetosphere Interactions: New Perspectives from Imaging,
AGU Geophysical Monograph 159, Proceedings of the 2004 Yosemite Workshop, 
(Burch, Schulz, Spence, eds.), 2005