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Ann. Geophys., 24, 529-542, 2006
www.ann-geophys.net/24/529/2006/
© European Geosciences Union 2006
Seasonal and diurnal variation of lightning activity over southern Africa and correlation with European whistler observations
A. B. Collier1,2, A. R. W. Hughes1, J. Lichtenberger3, and P. Steinbach4
1School of Physics, University of KwaZulu-Natal, 4041, Durban, South Africa
2Alfvén Laboratory, Royal Institute of Technology, SE-100 44, Stockholm, Sweden
3Space Research Group, Eötvös University, Budapest, Pf 32, H-1518, Hungary
4Research Group for Geoinformatics and Space Sciences, Eötvös University, Budapest, Pf 32, H-1518 Hungary
Abstract. Lightning Imaging Sensor (LIS) data have been analysed to ascertain the statistical pattern of
lightning occurrence over southern Africa. The diurnal and seasonal
variations are mapped in detail. The highest flash rates
(107.2 km-2 y-1) occur close to the equator but maxima are also
found over Madagascar (32.1 km-2 y-1) and South Africa
(26.4 km-2 y-1). A feature of the statistics is a relatively
steady contribution from over the ocean off the east coast of South Africa
that appears to be associated with the Agulhas current.
Lightning statistics are of intrinsic meteorological interest but they also
relate to the occurrence of whistlers in the conjugate region. Whistler
observations are made at Tihany, Hungary. Statistics reveal that the period
of most frequent whistler occurrence does not correspond to the maximum in
lightning activity in the conjugate region but is strongly influenced by
ionospheric illumination and other factors. The whistler/flash ratio,
R, shows remarkable variations during the year and has a peak that is
narrowly confined to February and March.
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