Accession Number : ADP006314

Title :   A Survey of Polar Cap F-Region Electron Densities Measured by the Sondrestrom Radar,

Corporate Author : LOCKHEED MISSILES AND SPACE CO INC PALO ALTO CA PALO ALTO RESEARCH LAB

Personal Author(s) : Robinson, R. M.

Report Date : 03 MAY 1990

Pagination or Media Count : 8

Abstract : The Sondrestrom incoherent scatter radar has been used to study F-region electron densities in the polar cap. The data were obtained while the radar antenna was scanned in the plane of the magnetic meridian. In this mode, electron densities are measured as a function of altitude and latitude so that ionospheric boundaries can be easily identified. One boundary that is present in much of the data is a vertical wall of electron density between 80 and 200 km altitude that separates the region of aurorally-produced electron density from the polar regions where auroral precipitation is absent. Based on this criterion we identified more than 500 radar scans during which the radar measured F-region electron densities in the polar cap. The data were sorted according to magnetic activity, solar flux, invariant latitude, and magnetic local time. Besides calculating average electron density profiles, we also examined the altitude and latitude variations of the F-region peak density. The peak density in the polar cap F region varies by a factor of four between solar zenith angles of 85 and 120 deg. The relative amplitude of large scale irregularities is approximately twice as large when the F-region is not sunlit. The only evidence for transport effects in the measured electron density is a factor of three decrease in peak density in the dawn local time sector for the same solar zenith angle.

Descriptors :   *IONOSPHERE, *RADAR REFLECTIONS, INCOHERENT SCATTERING, F REGION, ELECTRON DENSITY, POLAR REGIONS, GREENLAND, MAGNETIC FIELDS, RADAR ANTENNAS.

Subject Categories : Atmospheric Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE