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Title: Characteristics of ionospheric bubbles determined from aspect sensitive scatter spread F observed with Alouette 1

Abstract

Aspect sensitive scatter from bubbles is observed on a large percentage of equatorial Alouette 1 ionograms. The occurrence frequency of bubbles increases sharply (from zero) after sunset and reaches a maximum at about 23--24 hours local time. Near midnight, bubbles are observed in the topside ionosphere on about 65% of American and African satellite passes and on about 50% of Asian passes. The frequency of occurrence decreases gradually throughout the postmidnight and morning periods and becomes almost zero near noon. Averaged over the whole day, the occurrence of bubbles at Asian logitudes is about one half that at American and African longitudes. The occurrence of bubbles peaks at the December solstice for American longitudes and at the June solstice for Asian longitudes. The above observations imply that bubbles are initiated by field-aligned currents at the steep density gradient at the bottom of the postsunset F layer by the mechanism proposed by K. D. Cole. After initiation the Rayleigh-Taylor instability takes over to raise the bubbles through the F layer. Alouette 1 observations indicate that the bubbles rise to a maximum height of about 600--1000 km near midnight. The height then decreases gradually until some time after sunrise. Ray tracing, assumingmore » aspect sensitive scatter and a circular cross section for the field-aligned bubble, indicates that a particular, typical bubble was about 28 km in radius and intersected the vertical plane through the satellite in the magnetic east-west direction, about 550 km below and about 750 km to the east or west of the satellite. In the topside ionosphere below Alouette 1, bubbles never seem to occupy more than about 2% of the total space.« less

Authors:
Publication Date:
Research Org.:
Communications Research Centre, Department of Communications, Ottawa, Ontario, Canada K2H 8S2
OSTI Identifier:
5328629
Resource Type:
Journal Article
Journal Name:
J. Geophys. Res.; (United States)
Additional Journal Information:
Journal Volume: 85:A5
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; F REGION; IONOSPHERIC STORMS; DAILY VARIATIONS; GEOGRAPHICAL VARIATIONS; ION DENSITY; RAYLEIGH-TAYLOR INSTABILITY; EARTH ATMOSPHERE; INSTABILITY; IONOSPHERE; PLANETARY IONOSPHERES; VARIATIONS; 640201* - Atmospheric Physics- Auroral, Ionospheric, & Magetospheric Phenomena

Citation Formats

Muldrew, D B. Characteristics of ionospheric bubbles determined from aspect sensitive scatter spread F observed with Alouette 1. United States: N. p., 1980. Web. doi:10.1029/JA085iA05p02115.
Muldrew, D B. Characteristics of ionospheric bubbles determined from aspect sensitive scatter spread F observed with Alouette 1. United States. doi:10.1029/JA085iA05p02115.
Muldrew, D B. Thu . "Characteristics of ionospheric bubbles determined from aspect sensitive scatter spread F observed with Alouette 1". United States. doi:10.1029/JA085iA05p02115.
@article{osti_5328629,
title = {Characteristics of ionospheric bubbles determined from aspect sensitive scatter spread F observed with Alouette 1},
author = {Muldrew, D B},
abstractNote = {Aspect sensitive scatter from bubbles is observed on a large percentage of equatorial Alouette 1 ionograms. The occurrence frequency of bubbles increases sharply (from zero) after sunset and reaches a maximum at about 23--24 hours local time. Near midnight, bubbles are observed in the topside ionosphere on about 65% of American and African satellite passes and on about 50% of Asian passes. The frequency of occurrence decreases gradually throughout the postmidnight and morning periods and becomes almost zero near noon. Averaged over the whole day, the occurrence of bubbles at Asian logitudes is about one half that at American and African longitudes. The occurrence of bubbles peaks at the December solstice for American longitudes and at the June solstice for Asian longitudes. The above observations imply that bubbles are initiated by field-aligned currents at the steep density gradient at the bottom of the postsunset F layer by the mechanism proposed by K. D. Cole. After initiation the Rayleigh-Taylor instability takes over to raise the bubbles through the F layer. Alouette 1 observations indicate that the bubbles rise to a maximum height of about 600--1000 km near midnight. The height then decreases gradually until some time after sunrise. Ray tracing, assuming aspect sensitive scatter and a circular cross section for the field-aligned bubble, indicates that a particular, typical bubble was about 28 km in radius and intersected the vertical plane through the satellite in the magnetic east-west direction, about 550 km below and about 750 km to the east or west of the satellite. In the topside ionosphere below Alouette 1, bubbles never seem to occupy more than about 2% of the total space.},
doi = {10.1029/JA085iA05p02115},
journal = {J. Geophys. Res.; (United States)},
number = ,
volume = 85:A5,
place = {United States},
year = {1980},
month = {5}
}