An experimental study of wave packets in travelling ionospheric disturbances |
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Institution: | 1. Department of Management Sciences, COMSATS University, Islamabad, Pakistan;2. Department of Management Sciences, Bahria University, Islamabad, Pakistan;3. Energy and Sustainable Development (ESD), Montpellier Business School, Montpellier, France;4. Informetrics Research Group, Ton Duc Thang University, Ho Chi Minh City, Vietnam;5. Faculty of Social Sciences and Humanities, Ton Duc Thang University, Ho Chi Minh City, Vietnam;1. Department of Psychology, University of Pittsburgh, Pittsburgh, PA, 15213, USA;2. Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, 15213, USA;3. Department of Pediatrics, University of Pittsburgh, Pittsburgh, PA, 15213, USA;4. Center for the Neural Bases of Cognition, Pittsburgh, PA 15213, USA;5. Department of Psychology, Carnegie Mellon University, Pittsburgh, PA 15213, USA;1. University of Nova Gorica, Vipavska cesta 13, 5000, Nova Gorica, Slovenia;2. Royal Observatory of Belgium, 3 Avenue Circulaire, B-1180, Brussels, Belgium;3. University of Belgrade, Faculty of Mining and Geology, Physics Cathedra, Djusina 7, 11000, Belgrade, Serbia;4. Department of Physics, University of Otago, PO Box 56, Dunedin, 9054, New Zealand;5. British Antarctic Survey (UKRI-NERC), High Cross, Madingley Road, Cambridge, CB3 0ET, UK |
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Abstract: | The complex demodulation method was employed to analyse observations of TIDs carried out by means of multifrequency HF Doppler sounding at vertical incidence over Almaty (76°55′E, 43°15′N). Two types of behaviour of the amplitude and phase in the band-pass filtered Doppler shift oscillations were revealed. These were packet-like wave structures and quasi-stochastic TIDs. A study of the phase behaviour inside wave packets showed that most of them had a quasi-monochromatic structure, some of them had oscillations with a period which increased with time, and none had oscillations with a period which decreased with time. Phase jumps between nearby packets were explained as a result of interference between two adjacent packets having similar oscillation periods. A method of calculating the correlation coefficient for the wave packets propagating on a background of quasi-stochastic TIDs was developed. This showed that wave packets (having periods between 7 and 50 min) travelled in the vertical plane practically without any loss of coherence, while quasi-stochastic TIDs had a short coherence length; the velocity of the quasi-stochastic TIDs was noticeably larger than that of the wave packets. |
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