VHF ionospheric scintillations near the equatorial anomaly crest: solar and magnetic activity effects |
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| Institution: | 1. Saint-Petersburg State University of Aerospace Instrumentation, 67, Bolshaya Morskaya street, Saint-Petersburg 190000, Russia;2. Institute for Physics, Southern Federal University, Stachki, 194, Rostov-on-Don 344090, Russia;3. Physical Department, Southern Federal University, Sorge, 5 Rostov-on-Don 344090, Russia;4. SCiESMEX, Instituto de Geofisica, Unidad Michoacan, Universidad Nacional Autonoma de Mexico, Morelia, Michoacan, CP 58190, Mexico;5. Arctic and Antarctic Research Institute, 38 Bering street, Saint-Petersburg 199397, Russia;1. Pwani University, Department of Mathematics and Physical Sciences, Box 195-80108, Kilifi, Kenya;2. China Research Institute of Radiowave Propagation, No. 36, Xianshandong Road, Chengyang District, Qingdao, China;1. Department of Physics, University of Lagos, Yaba, Lagos, Nigeria;2. Department of Physical Sciences, Chrisland University, Owode, Abeokuta, Nigeria;1. School of Agricultural, Computational and Environmental Science, University of Southern Queensland, Springfield, Australia;2. School of Engineering and Physics, The University of the South Pacific, Suva, Fiji |
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| Abstract: | The paper presents a study of solar and magnetic activity effects on VHF ionospheric scintillations recorded during three and half years at Bhopal, a station near the northern crest of the equatorial anomaly in India. During E- (equinox) and D- (winter) months, scintillations occur mainly in the pre-midnight period whereas during J- (summer) months their occurrence is larger in the post-midnight period. Very intense scintillations (>20 dB) mainly occur in the pre-midnight period, and in the post-midnight period, the scintillations are generally moderate (5–10 dB) or weak (<5 dB). The nocturnal scintillation occurrence decreases with the decrease in solar activity from 1989 to 1992. Monthly mean scintillation occurrence changes according to solar activity during E- and D-months but not so during J-months. The effects of magnetic activity on scintillations vary with season and, in general, inhibit the scintillation occurrence in the pre-midnight period and enhance it a little in the post-midnight period, especially after 0300 hours IST (Indian Standard Time). For most of the severe magnetic storms in which Dst goes below ?125 nT and the recovery phase starts in the post-midnight to dawn local time sector, strong post-midnight scintillations, which sometimes extend for several hours beyond the local sunrise, are observed. |
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