Accession Number : ADP006275

Title :   Goose Bay Radar Observations of Earth-Reflected Atmospheric Gravity Waves in the High-Latitude Ionosphere,

Corporate Author : JOHNS HOPKINS UNIV LAUREL MD APPLIED PHYSICS LAB

Personal Author(s) : Ruohoniemi, J. M. ; Greenwald, R. A. ; Baker, K. B. ; Samson, J. C.

Report Date : 03 MAY 1990

Pagination or Media Count : 8

Abstract : An HF backscatter radar at Goose Bay, Labrador made it possible to observe irregularities in the distribution of ionospheric ionization at E and F region altitudes (100 - 600 km) in the high-latitude (65 - 85 deg Lambda) ionosphere. Recently it has been established that the passage of atmospheric gravity waves perturbs the ionosphere in ways that are readily detected in returns that reflect off the ionospheric layers. The particular strength of the technique lies in the nearly instantaneous measurement of gravity wave effects over large areas ( 1 million sq. km). With this information the propagation of gravity waves can be accurately modelled. Generally gravity waves are observed during daylight hours propagating away from the auroral electrojets. The propagation mode involves penetration of wave energy through the lower atmosphere and subsequent reflection by the earth's surface. The frequencies associated with the waves lie in the 0.4 - 0.6 mHz range and the wavelengths vary from 300 to 500 km. The excitation sources appear to lie in the vicinity of the high-latitude electrojets. In this paper we outline the analysis of gravity wave effects on HF propagation and present an example of a modelled gravity wave event.

Descriptors :   *IONOSPHERIC DISTURBANCES, *GRAVITY WAVES, HIGH LATITUDES, RADAR REFLECTIONS, E REGION, F REGION, ELECTROJETS, HIGH FREQUENCY, AURORAE, DIURNAL VARIATIONS.

Subject Categories : Atmospheric Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE