Daytime F layer trough observed on a macroscopic scale

Journal Article · Sun Mar 01 04:00:00 EST 1987 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/JA092iA03p02571· OSTI ID:5399017

Whalen, J A ^[1]

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1. Air Force Geophysics Lab., Hanscom AFB, MA (United States)

This paper reports a new technique of observing the high-latitude ionospheric trough which defines its continuity in space and time on a macroscopic scale not previously possible. Vertical ionospheric soundings provide the observations in the midday to evening sector where the signature of the trough is found to be a bite-out' of a factor of 3-10 in the diurnal distribution of the solar produced electron density at the F layer maximum. The data base employed is that produced by the extensive array of ionospheric sounders operating at high latitudes in the northern hemisphere during the International Geophysical Year period of December 1958, hence at solar maximum. The worldwide extent, high density, simultaneity, and continuity of these measurements make possible the description of the trough for the first time as an integral, spatially continuous entity in its entire daytime extent and UT duration. The technique is demonstrated in studies of 4 days which span the range of activity for the month. On the most disturbed day the daytime trough is continuous in magnetic latitude, magnetic local time between (75{degree}, 1030) and (51{degree}, 1630) and remains nearly stationary in this frame of reference for a duration of 14.5 hours UT. A snapshot' constructed from multiple simultaneous observations on this day shows the trough to have a continuous length of 6 {times} 10{sup 3} km and an area of > 4 {times} 10{sup 6} km{sup 2}. The trough, which is also stable for similar durations on the other 3 days, is found to rotate clockwise to earlier magnetic local time by 5.5. hours and to expand equatorward in magnetic latitude by 20{degree} as activity increases from quiet to disturbed. Activity dependence and morphology are consistent with other observations that the trough locates rapid westward convection within the dusk convection cell.

• OSTI ID: 5399017
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 92:A3; ISSN 0148-0227; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

661320* -- Auroral
Ionospheric
& Magnetospheric Phenomena-- (1992-)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AURORAL OVAL
CONVECTION
CRITICAL FREQUENCY
DETECTION
DISTRIBUTION
EARTH ATMOSPHERE
EARTH PLANET
ELECTRON DENSITY
ENERGY TRANSFER
EXPANSION
F REGION
HEAT TRANSFER
IONIZATION
IONOSPHERE
MASS TRANSFER
MORPHOLOGY
NORTHERN HEMISPHERE
PLANETARY IONOSPHERES
PLANETS
PLASMA DENSITY
SPATIAL DISTRIBUTION