Accession Number : ADP006150

Title :   Specular Scatter: A New Mechanism for Ionospheric Backscatter,

Corporate Author : LOWELL UNIV MA CENTER FOR ATMOSPHERIC RESEARCH

Personal Author(s) : Sales, Gary S.

Report Date : MAY 1987

Pagination or Media Count : 8

Abstract : Recent investigation into backscatter from ionospheric irregularities at high frequency (3 to 30 MHz) has indicated that the usual scatter mechanism requiring orthogonality with the field-aligned irregularities in the E and F region of the ionosphere is not sufficient to explain all the observations. Particularly the range dependence of ionospheric clutter as seen by an OTH radar system looking into or near the auroral region poses a major problem. Assuming field-aligned electron density irregularities, ray tracing shows that clutter originates in the region where the ray becomes perpendicular to the earth's magnetic field lines within the ionosphere. The intensity of these irregularities can be described in terms of Delta/N, the fractional deviation from the ambient electron density. The actual distribution of electron density fluctuations is described using a power law spectrum with an exponent of n = 2. As will be shown, the orthogonality condition can always be satisfied in the F region of the ionosphere at mid and high latitudes near the reflecting point where the rays have become near-horizontal.

Descriptors :   *IONOSPHERIC PROPAGATION, *ELECTROMAGNETIC SCATTERING, HIGH FREQUENCY, OVER THE HORIZON RADAR, E REGION, F REGION, BACKSCATTERING, AURORAE, IONOSPHERIC DISTURBANCES, ELECTRON DENSITY, RAY TRACING, CLUTTER, SYMPOSIA.

Subject Categories : Radiofrequency Wave Propagation
      Atmospheric Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE