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http://hdl.handle.net/2122/8978
Authors: | Baskaradas, J. A.* Bianchi, S.* Pietrella, M.* Pezzopane, M.* Sciacca, U.* Zuccheretti, E.* |
Title: | Description of ionospheric disturbances observed by Vertical Ionospheric Sounding at 3 MHz | Journal: | ANNALS OF GEOPHYSICS | Series/Report no.: | 1/57 (2014) | Issue Date: | 2014 | DOI: | 10.4401/ag-6345 | Keywords: | Fading fluctuation Ionospheric irregularities Multipath fading Ionograms |
Subject Classification: | 01. Atmosphere::01.02. Ionosphere::01.02.02. Dynamics 01. Atmosphere::01.02. Ionosphere::01.02.04. Plasma Physics 01. Atmosphere::01.02. Ionosphere::01.02.05. Wave propagation 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques |
Abstract: | High Frequency radio waves reflected by the ionosphere can provide a relevant amount of information within the composite received signal. The ionosphere is indeed a frequency dispersive, bi-refractive, absorbing medium, in which multipath propagation occurs due to disturbance on a varied time-spatial scale. On the time-spatial level of Small Scale Disturbances (SSD) the ionosphere dynamics, detectable by Vertical Ionospheric Sounding (VIS), is mainly dependent on wrinkled layers acting as multi-reflectors. The present paper discusses different aspects of the effects of multipath fading suffered by the wave along the propagation path and potentially associated with SSD. To achieve these objectives, a VIS campaign at a fixed frequency of 3.0 MHz was conducted at the ionospheric observatory in Rome (Latitude 41.8 N; Longitude 12.5 E), by collecting a series of measurements of the power variations in received echo signals recorded between two consecutive ionograms whose sounding repetition rate was set to 15 min. The obtained results show that: 1) the fading suffered by the wave follows either a Rayleigh trend or a Nakagami-Rice trend, or a mix of them, the mixed case being the most frequent (about 65 % of the analysed cases); 2) the predominant periodicities characterizing the power variation are less than 25 s; such values are compatible with the small scale ionospheric disturbances; 3) for all the 24 hours of the day the ionospheric reflector is pretty stable and for time intervals of 10-30 s the periods of stability occur with a percentage of occurrence ranging between 55% and 95 %; for time intervals of 190- 210 s the periods of stability occur instead with a percentage of occurrence ranging between 5% and 54 %. |
Appears in Collections: | Article published / in press |
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2014_AnnalsOfGeophysics_3MHz.pdf | full text | 713.64 kB | Adobe PDF | View/Open |
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