Low Frequency Modulation of Plasmas and Soft Electron Precipitation Near the Dayside Cusp.
Abstract
The HILAT satellite trajectory was approximately aligned with the noon-midnight meridian while crossing the northern polar cusp/cleft region, during (1) an increase in scintillations of radio signals, (2) strongly variable fluxes of precipitating low-energy electrons (3) gradients in the thermal ion density, (4) fluctuations in the east west component of the ion draft velocities superimposed on the noon sector convection pattern and (5) field aligned currents. In the region corresponding to the highest level of radio scintillations, fluctuations in electron fluxes were detected on a time scale of half a second superimposed on a low energy inverted V event. The analysis of these measurements which provide information on both large and small scale dynamics of the dayside cusp leads to the following conclusions: (1) the large scale convection pattern is characteristic for the northern hemisphere high latitude ionosphere when the interplanetary magnetic field has negative Y and Z components; (2) the most intense scintillations and the cusp field aligned Currents occur on recently opened magnetic lines; (3) plasma created by increased fluxes of precipitating low-energy convects antisunward with velocity of 0.5 km/sec; (4) enhanced chemical reactions due to the Joule heating associated with large electric fields maximize at the equatorward edge of the cusp leading to the net depletion in TEC and plasma density measurements; (5) plasma irregularities throughout the F region are formed due to a combined effect of structured soft electron precipitation and current convective instabilities; (6) There are potential drops of a few tens of volts between the altitude of the satellite (830 km) and the lower ionosphere.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 1986
- Accession Number
- ADA176894
Entities
People
- Ewa M. Basinska
- Frederick J. Rich
- Paul F. Fougere
- Sunanda Basu
- William J. Burke
Organizations
- Regis University