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https://ptsldigital.ukm.my/jspui/handle/123456789/487265Full metadata record
| DC Field | Value | Language |
|---|---|---|
| dc.contributor.advisor | Mardina Abdullah, Professor Dr. | - |
| dc.contributor.author | Aramesh Seif (P53270) | - |
| dc.date.accessioned | 2023-10-11T02:31:34Z | - |
| dc.date.available | 2023-10-11T02:31:34Z | - |
| dc.date.issued | 2014-03-28 | - |
| dc.identifier.other | ukmvital:74847 | - |
| dc.identifier.uri | https://ptsldigital.ukm.my/jspui/handle/123456789/487265 | - |
| dc.description | Ionospheric scintillations are random fluctuations in the intensity and phase-received signals resulting from plasma density irregularities in the ionosphere. Such variations can significantly affect the accuracy and reliability of satellite communication and navigation systems, such as Global Positioning System (GPS), by degrading signals. Therefore, the intensity of ionospheric scintillation is a crucial parameter to estimate the effect on space-based navigation and communication system, which is most likely to occur in equatorial regions such as Malaysia. Ionospheric scintillations at gigahertz (GHz) frequencies have been observed during both daytime and nighttime. Most of the previous studies on ionospheric scintillation are highly concerned with nighttime at equatorial regions and low and high latitudes but have insufficiently investigated daytime scintillation particularly near the magnetic dip equator. Therefore, further investigation during daytime is needed. This study aims to investigate ionospheric scintillation in the range of GHz over Malaysia. The sites are particularly interesting for their locations, near the magnetic dip equator. The study addresses three objectives: to investigate the characteristics of diurnal and seasonal ionospheric scintillations, to analyze characteristics of nighttime and daytime ionospheric scintillation, and to investigate characteristics of daytime scintillation and its relationship with blanketing type of Es (Esb) in the vicinity of magnetic dip equator using Tsunoda model. Data used are from a ground-based, dual-frequency receiver called GPS Ionospheric Scintillation and Total Electron Content (TEC) Monitor, which was installed at two stations Universiti Kebangsaan Malaysia (UKM) and Langkawi from 2009 to 2011, and from 2010 to 2011, respectively. To investigate ionospheric scintillation, ionospheric parameters such as amplitude scintillation (S4 index), phase scintillation, TEC, rate of TEC (ROT), and ROT index (ROTI) are analyzed. In the analysis, scintillations are categorized as strong S4 ≥ 0.4, moderate 0.3 ≤ S4 ≤ 0.4, and weak 0.2 ≤ S4 ≤ 0.3. Results show that a significant nighttime amplitude scintillation event with 0.4 ≤ S4 < 0.6 mainly occurred in March, September, and October, whereas a significant daytime amplitude scintillation activity with 0.3 ≤ S4 < 0.5 occurred in November and December. The month-to-month occurrence rate of ionospheric scintillation shows that amplitude scintillation activities are maximum during equinox months, moderate during winter months, and minimum during summer months. The nighttime amplitude scintillation observed at the UKM station always occurred with phase scintillations, total TEC depletions, ROT fluctuations, and ROTI enhancement. TEC depletions and ROT fluctuations during daytime amplitude scintillation were weaker than those during nighttime, which may be caused by small-scale irregularities in E region, called sporadic E (Es). The occurrences of nighttime amplitude scintillation may be caused by ionospheric irregularities in F region. The characteristics of daytime scintillation in the vicinity of magnetic dip equator show seasonal dependence, with a maximum during equinox months and minimum during summer, as well as latitudinal dependence, in which the intensity of daytime scintillation increases with dip latitude from near the magnetic dip equator to away from it. The results from this study also reveals that the latitudinal distribution of scintillations is consistent with the hypothesis that horizontal transport of Esb patches is controlled by the polarization electric field associated with the equatorial electrojet, as well as by the vertical shear in the neutral wind, as proposed by Tsunoda model, and the plasma-density irregularities responsible for daytime scintillations appeared to be produced by the gradient drift instability (GDI).,PhD | - |
| dc.language.iso | eng | - |
| dc.publisher | UKM, Bangi | - |
| dc.relation | Faculty of Engineering and Built Environment / Fakulti Kejuruteraan dan Alam Bina | - |
| dc.rights | UKM | - |
| dc.subject | Investigation of ionospheric scintillation | - |
| dc.subject | Ionospheric scintillation | - |
| dc.subject | GPS sensing | - |
| dc.subject | Solar minimum | - |
| dc.subject | Universiti Kebangsaan Malaysia -- Dissertations | - |
| dc.title | Investigation of ionospheric scintillation using gps sensing during solar minimum | - |
| dc.type | Theses | - |
| dc.format.pages | 134 | - |
| Appears in Collections: | Faculty of Engineering and Built Environment / Fakulti Kejuruteraan dan Alam Bina | |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| ukmvital_74847+Source01+Source010.PDF Restricted Access | 2.14 MB | Adobe PDF |  View/Open |
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