Spatial distribution and variation of narrow L-shell bands in the plasmasphere supporting field-aligned propagating modes as observed by the RPI/IMAGE satellite Sales, G., Reinisch, B.W., Song, P., Huang, X., Galkin, I., Gallagher, D.L. Field-aligned propagating (FAP) modes have been a regular characteristic of the RPI/IMAGE plasmagrams from the beginning of the experiment. LF/MF (in the range of 3 kHz to 3 MHz) transmitted radio signals from the satellite propagate in the magnetic meridian plane along the magnetic field line passing through the satellite position to both the northern and southern hemispheres where they reflect at a level that depends on the sounding frequency. This analysis has shown that these hemispherical reflections occur on about 20\% of the plasmagrams while the IMAGE satellite is between L = 2.5 and L = 4.5. Occurrences of these FAP plasmagrams were consistently organized into two L-shell bands. The first band was found at L = 3.2 +- 0.2 moving in and out slowly over a period of a few days. This band, with a width of DL >> 0.2, is always present. The second observed band also supports hemispherical propagation and was found at higher L-shells, ranging from L = 3.5 under quiet magnetic conditions, moving to L = 4.0 as the level of magnetic activity increases. During high magnetic activity conditions this outer band disappears. When RPI/IMAGE passed through the inner band the probability of the appearance of FAP modes was 98% while for the outer band this percentage drops to 91%. Analyzing 5 months of data using an RPI sounding program that makes a new plasmagram every 3 minutes as the satellite traverses the plasmasphere has lead to a comprehensive description of these bands that can be mapped down to the mid-latitude trough region. Comparison is made between the plasmaspause location and the tail region as determined using other sensors with respect to the position of the two bands under changing magnetic conditions. _______________ Fall 2002 Meeting of the American Geophysical Union San Francisco, CA, USA, 6-10 December 2002