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Ann. Geophys., 19, 59-69, 2001
www.ann-geophys.net/19/59/2001/
© European Geosciences Union 2001
Sporadic-E associated with the Leonid meteor shower event of November 1998 over low and equatorial latitudes
H. Chandra1, S. Sharma1, C. V. Devasia2, K. S. V. Subbarao2, R. Sridharan2, J. H. Sastri3, and J. V. S. V. Rao3
1Physical Research Laboratory, Ahmedabad, India 380 009
2Space Physics Laboratory, VSSC, Trivandrum, India 695 022
3Indian Institute of Astrophysics, Bangalore, India 560 034
Abstract. Rapid radio soundings were
made over Ahmedabad, a low latitude station during the period 16–20 November
1998 to study the sporadic-E layer associated with the Leonid shower activity
using the KEL Aerospace digital ionosonde. Hourly ionograms for the period 11
November to 24 November were also examined during the years from 1994 to 1998. A
distinct increase in sporadic-E layer occurrence is noticed on 17, 18 and 19
November from 1996 to 1998. The diurnal variations
of f0Es and fbEs also show significantly enhanced values for the morning hours of 18 and 19
November 1998. The ionograms clearly show strong sporadic-E reflections at times
of peak shower activity with multiple traces in the altitude range of 100–140
km in few ionograms. Sporadic-E layers with multiple structures in altitude are
also seen in some of the ionograms (quarter hourly) at Thumba, situated near the
magnetic equator. Few of ionograms recorded at Kodaikanal, another equatorial
station, also show sporadic- E reflections in spite of the transmitter power
being significantly lower. These new results highlighting the effect of intense
meteor showers in the equatorial and low latitude E-region are presented.
Key words. Ionosphere (equatorial ionosphere) – Radio
science (ionospheric physics)
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