Electron Density in the Magnetosphere
Abstract
Observations of the electron density n(sub e) based on measurement of the upper hybrid resonance frequency by the Polar spacecraft Plasma Wave Instrument (PWI) are available for March 1996 to September 1997, during which time the Polar orbit sampled all MLT values three times. In a previous study, we modeled the electron density dependence along field lines as n(sub e) = n(sub e)o(R(sub max/R)(exp alpha), where n(exp e)O is the equatorial electron density, R(sub max)= LR(sub E) is the maximum geocentric radius R to any point on the field line, and alpha = alpha(sub model) = 8.0 - 3.0 log(sub 10)n(sub e)o) + 0.28(log(sub 10)n(sub e)O)2 - O.43(R(sub max)/R(sub E)), for all categories of plasma (plasmasphere and plasmatrough). (In the formula for alpha(sub model), n(sub e)O is expressed in /cu cm) Here, we illustrate the field line dependence using several example events. We show that the plasmapause is much more evident on the large radius portion of the orbit and that at R ^2 R(sub E) the electron density tends to level out at large R(sub max) to a constant value ^lOO /cu cm. We also present an example of plasmaspheric plasma extending out to at least L^9 on the dawnside during particularly calm geomagnetic conditions (as indicated by low Kp). Then we present the average equatorial profiles of n(sub e) 0 versus R(sub max) for plasmasphere and plasmatrough. Our average plasmasphere profile is found to have values intermediate between those based on the models of Carpenter and Anderson and Sheeley et al.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 2004
- Accession Number
- ADA430435
Entities
People
- J D Menietti
- Joel Goldstein
- R. E. Denton
- R. R. Anderson
- S. L. Young
Organizations
- Air Force Research Laboratory