Developing an Empirical Density Model of the Plasmasphere
Using IMAGE/RPI Observations

Xueqin Huang, Bodo W. Reinisch, Paul Song
  Environmental, Earth, and Atmosphereic Science Department,
  Center for Atmospheric Research, University of Massachusetts,
  Lowell, MA 01854, USA

James L. Green
  NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA

Dennis L. Gallagher
  NASA Marshal Space Flight Center, 320 Sparkman Drive,
  Huntsville, AL 35805, USA

The radio plasma imager (RPI) on the IMAGE satellite performs radio
sounding in the magnetosphere, transmitting coded signals stepping
through the frequency range of interest and receiving the returned
echoes. The measurements provide the echo amplitude as a function of
frequency and echo delay time on a so-called plasmagram. A newly
developed algorithm inverts the echo traces on a plasmagram to electron
density spatial distributions. Based on these observed density
distributions, an empirical model is constructed to describe the
two-dimensional density distribution in the inner magnetosphere.