Role of acoustic-gravity waves in generating equatorial ionospheric irregularities

Thesis/Dissertation · Tue Jan 01 00:00:00 EST 1980

OSTI ID:5422570

Argo, P E

Irregularities in the equatorial ionospheric plasma (F-layer) have been observed and studied for many years. Even so, the creation mechanisms have successfully remained a source of controversy for equally many years. This is mainly due to the difficulty in observing the irregularities, because in situ measurements give a spatial trace at a near single time, while radio observations have tended to give a series of height profiles with changing time. One mechanism is the spatial resonance amplification of traveling ionospheric disturbance (TIDs) generated by acoustic gravity waves. As the wave profile in the plasma steepens, the stored energy begins to release through the Rayleigh-Taylor instability, which then creates a spectrum of smaller scale irregularities. In this dissertation the interaction of the acoustic gravity wave and the ionospheric plasma are examined, and it is found that the above mechanism is indeed feasible. In Chapter 3, the interaction between a neutral wave and the plasma is quantified, and the condiions for growth of resonant plasma waves is established. These conditions are met during the post-sunset period near the geomagnetic equator, which is exactly when and where the irregularities are encountered. For irregularity generation the Rayleigh-Taylor mechanism requires a steep positive gradient of density - a fact that previously has seemed to be impossible on the topside of the F-layer. However, in this thesis it is shown that acoustic gravity waves can generate positive slopes even on the topsideF-layer. Consequently, acoustic gravity waves constitute a single mechanism that can be used to explain both bottomside and topside irregularities. Experimental evidence for the creation of equatorial ionospheric irregularities by acoustic gravity waves has been sparse, although wavelike structures appear to permeate the irregularity profiles.

• Research Organization: California Univ., San Diego, La Jolla (USA)
• OSTI ID: 5422570
• Resource Relation: Other Information: Thesis (Ph. D.)
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
F REGION
TRAVELLING IONOSPHERIC DISTURBANCE
GRAVITY WAVES
GEOMAGNETIC EQUATOR
INTERACTIONS
PLASMA WAVES
RAYLEIGH-TAYLOR INSTABILITY
DISTURBANCES
EARTH ATMOSPHERE
INSTABILITY
IONOSPHERE
IONOSPHERIC STORMS
PLANETARY IONOSPHERES
640201* - Atmospheric Physics- Auroral
Ionospheric
& Magetospheric Phenomena