Distribution of density along magnetospheric field lines
Abstract
We discuss the dependence of magnetospheric plasma density along field lines. Observations of the electron density N_e based on measurement of the upper hybrid resonance frequency by the Polar spacecraft Plasma Wave Instrument (PWI) have been used to derive a statistical model for the average field line dependence of electron density ne0. Assuming a power law form along field lines N_e = ne0 ( Rmax / R)^α, where ne0 is the equatorial electron density and Rmax ≈ L R_E is the maximum geocentric radius R to any point on the field line, we model the statistical average of α as αmodel = 8.0 - 3.0 log10{ne0} + 0.28 ( log10{ne0} )^2 - 0.43(Rmax/R_E) for all categories of plasma (plasmasphere and plasmatrough), with an average error of 0.65. The data set on which this result is based is limited to 2.5 R_E <= Rmax <= 8.5 R_E, 2 R_E <= R <= Rmax, and 2 <= ne0 <= 1500 cm-3. There is no remaining dependence of the average α - αmodel on MLT or K_p. We also present determinations of the parallel dependence of mass density using the harmonics of toroidal Alfv&{acute;e}n wave eigenmodes observed by the CRRES spacecraft. We then compare the inferred mass density at the spacecraft location to the electron density determined from the plasma wave experiment onboard CRRES.
- Publication:
-
EGS - AGU - EUG Joint Assembly
- Pub Date:
- April 2003
- Bibcode:
- 2003EAEJA....14323D