Postsunset rise of F layer height in the equatorial region and its relation to the F layer dynamo polarization fields

Journal Article · Tue May 01 00:00:00 EDT 1990 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/JA095iA05p06237· OSTI ID:5028664

Goel, M K; Singh, S S; Rao, B C.N. ^[1]

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1. National Physical Lab., New Delhi (India)

The ionosonde data are studied for equatorial station, Thumba, to delineate various features of the evening height rise of F layer. Sharp increase of h'F and h{sub p}F2 is observed in the postsunset period for high solar activity. Seasonal variation is observed in this increase of h'F and it is maximum for equinox months. For summer months, there is a delay of about an hour in the time of occurrence of h'F (peak) as compared to winter and equinox months. This delay is shown to be associated with the delay in sunset times in the conjugate E regions. As for magnetic activity dependence, it is found that this height increase is less pronounced for disturbed days for winter and equinox whereas for summer it is marginally higher over the quiet day values. Further, it is observed that the value of h'F (peak) during disturbed periods is almost at the same value of 350 km for all the three seasons. Thus the seasonal variation of magnetic activity effects appears to be mainly governed by the average seasonal variation for quiet times. The increase in F layer height is due to zonal eastward electric fields developed after sunset which is believed to be due to F region dynamo fields. While the main driving force for these fields is the zonal neutral winds, the development of these fields depend on the ratio of the F region to E region conductivity and the longitudinal gradient in the E region conductivity. Experimental observations of both the neutral winds and ionospheric conductivities are examined for their variation with solar activity, season and magnetic activity as both these factors will contribute for the various observed features of the height rise.

• OSTI ID: 5028664
• Journal Information: Journal of Geophysical Research; (United States), Vol. 95:A5; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
F REGION
ELECTRIC FIELDS
VIRTUAL HEIGHT
COMPARATIVE EVALUATIONS
DATA
E REGION
ELECTRIC CONDUCTIVITY
ELECTRON DENSITY
EQUATOR
IONOSONDES
SEASONAL VARIATIONS
SOLAR ACTIVITY
DIMENSIONS
EARTH ATMOSPHERE
ELECTRICAL PROPERTIES
ELECTRONIC EQUIPMENT
EQUIPMENT
EVALUATION
HEIGHT
INFORMATION
IONOSPHERE
PHYSICAL PROPERTIES
PLANETARY IONOSPHERES
RADIO EQUIPMENT
VARIATIONS
640201* - Atmospheric Physics- Auroral
Ionospheric
& Magetospheric Phenomena