VLF Sferics Propagating in the Earth-ionosphere Waveguide
The electromagnetic waves originating in lighting discharges at frequencies in the VLF band are reflected by the ground as well as by the conducting layer of the ionosphere and thus they are guided efficiently around the earth. As in this earth-ionosphere waveguide sferics propagate with low loss, they can be detected even at long distances from their source locations. Our observations in a tropical country India, over three decades, on VLF propagation reveal some interesting phenomena under realistic conditions. The variations of the overall intensity of radio atmospheric signal at the time of sunrise and sunset as well as by the so called cosmic ray layer formation after sunrise have been critically examined besides investigations on geomagnetic effects producing long period fading in sferics level. The effects of land and sea thunderstorms in the sferics level occurring over this area have also been taken into consideration. As the wave propagates over greater distances, the excitation and attenuation vary significantly with the parameters of the waveguide, such as reflexction height, anisotropy etc. which change over time and also over the typically long VLF propagation path.
A.B.Bhattacharya S.Joardar R.Bhattacharya S.Sarkar S.Das
Department of Physics,University of Kalyani,Kalyani 741235,West Bengal,India Giant Meterwave Radio Telescope,Tata Institute of Fundamental Research Khodad,Narayagaon,Pune 410504 Department of Environmental Science,University of Kalyani Kalyani 741235,West Bengal,India Department of Physics,University of Kalyani,Kalyani 741235,West Bengal,India;Department of Physics,S
国际会议
Progress in Electromagnetics Research Symposium 2009(2009年电磁学研究新进展学术研讨会)(PIERS 2009)
北京
英文
1396-1399
2009-03-23（万方平台首次上网日期，不代表论文的发表时间）