Дисертації з теми "Ionospheric variations"
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Thomas, Edwin Christopher. "Phase and amplitude variations in the wave fields of ionospherically reflected radio waves." Thesis, University of Leicester, 1986. http://hdl.handle.net/2381/35807.
Повний текст джерелаChoosakul, Nithiwatthn. "Study on the periodic ionospheric variations after large earthquakes using GPS data." 京都大学 (Kyoto University), 2009. http://hdl.handle.net/2433/126572.
Повний текст джерела0048
新制・課程博士
博士(理学)
甲第14895号
理博第3464号
新制||理||1507(附属図書館)
27333
UT51-2009-M809
京都大学大学院理学研究科地球惑星科学専攻
(主査)教授 町田 忍, 教授 家森 俊彦, 教授 里村 雄彦
学位規則第4条第1項該当
Shim, JA Soon. "Analysis of Total Electron Content (TEC) Variations in the Low- and Middle-Latitude Ionosphere." DigitalCommons@USU, 2009. https://digitalcommons.usu.edu/etd/403.
Повний текст джерелаJacobi, Christoph, Claudia Unglaub, Gerhard Schmidtke, Robert Schäfer, and Norbert Jakowski. "Delayed response of global ionospheric electron content to EUV variations derived from combined SolACES-SDO/EVE measurements." Universität Leipzig, 2015. https://ul.qucosa.de/id/qucosa%3A16645.
Повний текст джерелаDie ionosphärische Antwort auf Variationen des solaren EUV im Zeitraum 2011-2014 wird anhand eines Proxys dargestellt, welcher die primäre Ionisation auf der Basis gemessener solare EUV-Spektren beinhaltet. Die täglichen Werte werden mit Analysen des global gemittelten Gesamtelektronengehalts verglichen. Auf Zeitskalen der solaren Rotation und länger findet sich eine Zeitverzögerung zwischen der EUV-Variation und des derjenigen des Gesamtelektronengehalts von ein bis 2 Tagen, welche auf dynamische Prozesse im System Thermosphäre/Ionosphäre hinweist. Die Verzögerung ist auf kurzen Zeitskalen nicht zu sehen. Wenn diese Verzögerung berücksichtigt wird, erhöht sich die durch EUV-Variationen erklärte Varianz des Elektronengehalts von 71% auf 76%.
Nguyen, Thai Chinh [Verfasser], Harald [Akademischer Betreuer] Schuh, Mahdi [Akademischer Betreuer] Alizadeh, Harald [Gutachter] Schuh, Mahdi [Gutachter] Alizadeh, and Lung-Chih [Gutachter] Tsai. "Use of the East Asia GPS receiving network to observe ionospheric VTEC variations, scintillation and EIA features during the Solar Cycle 24 / Thai Chinh Nguyen ; Gutachter: Harald Schuh, Mahdi Alizadeh, Lung-Chih Tsai ; Harald Schuh, Mahdi Alizadeh." Berlin : Technische Universität Berlin, 2021. http://d-nb.info/1231908394/34.
Повний текст джерелаRaghuvanshi, Anurag. "Characterization of Airborne Antenna Group Delay as a Function of Arrival Angle and its Impact on Accuracy and Integrity of the Global Positioning System." Ohio University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1533314646617932.
Повний текст джерелаPalmer, Jonathan Richard. "Plasma density variations in the aurora." Thesis, University of Southampton, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.262167.
Повний текст джерелаHui, Debrup. "Altitudinal Variability of Quiet-time Plasma Drifts in the Equatorial Ionosphere." DigitalCommons@USU, 2015. https://digitalcommons.usu.edu/etd/4536.
Повний текст джерелаWyllie, Scott John, and scott wyllie@rmit edu au. "Modelling the Temporal Variation of the Ionosphere in a Network-RTK Environment." RMIT University. Mathematical and Geospatial Sciences, 2007. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080617.161323.
Повний текст джерелаLiperovskaya, E. V., M. Parrot, V. V. Bogdanov, Claudia-Veronika Meister, M. V. Rodkin, and V. A. Liperovsky. "On long-term variations of foF2 in the mid-latitude ionosphere before strong earthquakes." Universität Potsdam, 2006. http://opus.kobv.de/ubp/volltexte/2007/1501/.
Повний текст джерелаJacobi, Christoph, Norbert Jakowski, Gerhard Schmidtke, and Thomas N. Woods. "Delayed response of the global total electron content to solar EUV variations." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-212283.
Повний текст джерелаAmin, Mahmud Mohammed. "Influence of lightning on electron density variation in the ionosphere using WWLLN lightning data and GPS data." Master's thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/13565.
Повний текст джерелаIn this study we have demonstrated that a seasonal and diurnal correlation exists between occurrence frequencies of wave-like structures in the form of Traveling Ionospheric Disturbances (TID) in the ionosphere and tropospheric lightning in the mid-latitude region over South Africa. Lightning induced changes in total electron content (TEC) are strongest between September and March, with the more-pronounced effects occurring 12:00 - 22:00 UT, but from April through August there is a low probability of having significant lightning-induced TID occurrence. The strongest oscillations in the total electron content of the ionosphere have dominant periods of range 0.6 to 0.8 and 1.2to 2.5 hours, typical periods for medium scale TIDs and large scale TIDs respectively. Since ionospheric scintillation is caused by irregularities in electron density which act as wave scatterers, it is feasible that lightning-induced TIDs may provide the mechanism for causing the concomitant and co-located changes in ionospheric total electron con-tent that was observed. Both the lightning and the ionospheric irregularity have spatial dependence over South Africa dominating around Bloemfontein. We have also found a strong seasonal and diurnal correlation between occurrence frequencies of the high rate of change of TEC index (ROTI _ 0.8 TECU/min) as a proxy for amplitude scintillationS4 index and lighting stroke rate. The correlation coefficient linking diurnal lightning stroke rate and high ROTI is found to be about 86%. While the seasonal correlation between the monthly average ROTI and average stroke rate is about 70%, the seasonal average ROTI and average stroke rate correlation is found to be about 84%. This there-fore implies that the presence of lightning is a likely cause of the generation of TIDs and subsequent irregularities in the ionosphere.
Kawamura, Seiji. "A study of wind variations and their effects on the mid latitude ionosphere and thermosphere based on the MU radar observations." 京都大学 (Kyoto University), 2003. http://hdl.handle.net/2433/148790.
Повний текст джерелаLiu, Chih-Min, and 劉智旻. "Variations of Ionospheric electron temperature during earthquake period." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/vtzfy7.
Повний текст джерела國立中央大學
太空科學研究所
96
Pre-seismo-ionospheric signatures are studied by comparing variations in the electron temperature during the occurrence of large earthquake (M≧6.0). The ionospheric electron temperature was measured by electron temperature probe (ETP) on board Hinotori satellite during the period form March 1981 to June 1982. Eleven earthquakes in the vicinity of Taiwan and Philippines area are isolated and examined. Four of them show that anomalous deviations between observed Te and the associated empirical model around the dusk period or afternoon overshoot period(1500LT – 2000LT) appear from about 5 days before to 5 days after the earthquakes. A westward electric field possibly generated during the earthquake preparation period due to the change of the charge distribution. We also discuss the ELF(Extremely Low Frequency) emission observed by DE2 satellite.
Ho, Wan-chien, and 何萬謙. "Variations of ionospheric neutral densities in response to solar activity." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/71310393180035983666.
Повний текст джерела國立中央大學
太空科學研究所
102
This thesis focuses on the studies of variations of neutral densities at a height of 410 Km in response to solar activity. It use solar radiation indices F10.7 and EUV to linearly fit neutral density measured by the Challenging Minisatellite Payload (CHAMP) satelliteduring the period 2003 - 2008. Aclearly phase delay in solar radiation and neutral density have been found when we were doing data analysis. It's also pointed out that neutral density variation has a time delay with solar radiation in the previous papers. In this study, we could get a conclusion that the time delay is one day during 2003 to 2008. In doing the linear regression,the result from multiple parameters is almost the same as that from single parameter. And, because of the more completeness of the observations of F10.7 than EUV, we decide to use F10.7 index to be the main parameter in the following studies. To compare original data of neutral density with the fitted data has a significant difference in the period of low solar activity. The difference has high relation with Kp index. Additional linear regression is required for these differences with Kp index.The results indicate that solar radiation is a dominate factor in the variations of neutral densities in the period of high solar activity, and geomagnetic activity produced by the solar wind becomes important in the low solar activity. The difference between original data of neutral density with the fitted data has a period of 130 days, which can be attributed to the satellite orbit.Removement of this component can increase the correlation coefficient of the original data the fitted data up to 0.95. But this effect is only important in the period near solar minimum.
Hartman, William Andrew. "Longitudinal and seasonal variations in the topside equatorial vertical ion drift near 0600, 0930, 1800 and 2130 LT /." 2007. http://proquest.umi.com/pqdweb?did=1296113141&sid=1&Fmt=2&clientId=10361&RQT=309&VName=PQD.
Повний текст джерелаJung, Ting-Kuo, and 鍾鼎國. "Ionospheric variation in presunrise and postsunset period." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/u2p242.
Повний текст джерела國立中央大學
太空科學研究所
94
Abstract Examining the parameters foF2、 h'F、 foEs and h'Es recorded by ionosonde to study the diurnal、 seasonal、latitudinal and solar activity variations in heights and plasma frequencies. The results show that foF2 yields maximum values at the two equatorial anomaly regions. The minimum values in the northern and southern anomaly regions appear in summer and winter, respectively. In general, the foF2 value is in proportion to the sunspot number. It is found that there are always exist ionospheric height lift in pre-sunrise and post sunset periods at higt attitude and h'F lifts in its attitude during pre-sunrise and post sunset periods. For the latitudinal distribution the pre-sunrise covers a greater range in southern hemisphere than in northern. Moreover, the pre-sunrise lifts in the northern and southern reach their maximum va1ues in winter and spring, respectively. The lifts of the post sunset appear mainly in stations HU、VA and TT of the southern hemisphere. The most clear signatures usually found in summer. The lift in altitude is also in proportion to the sunspot number. The foEs value in northern hemisphere is possibly greater than 5MHz. No obvious relationship can be found between foEs value and sunspot. h'Es lifts its altitude simply during morning period in winter and early spring and during both early morning and afternoon periods during late spring-fall. The lifts increase while the latitude decreases in the northern hemisphere. However, there is no latitudinal and solar activity effect found in the southern hemisphere. Finally, the lifts signatures in h'F and h'Es indicate that the E × B vertical drift and Zonal/meridional wind plays an important role.
Lin, Chien-hung, and 林建宏. "Low-Latitude Ionosphere Variations during Magnetic Disturbances." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/59553923513793522097.
Повний текст джерела國立中央大學
太空科學研究所
93
The low latitude ionosphere is unique in that the magnetic field is nearly horizontal, so that zonal electric fields, produced by the neutral wind dynamo during quiet geomagnetic times, can transport the plasma vertically through the E×B drift. This quiet-time vertical drift is upward during the daytime, causing plasma to drift to higher altitudes, from where it diffuses down along magnetic fields to higher latitudes creating two plasma crests on both sides of the magnetic equator. This feature is called the equatorial ionization anomaly (EIA), and the effect of transporting the plasma from the magnetic equator to higher latitudes is described as the fountain effect [Duncan 1960; Wright 1962; Hanson and Moffett 1966; Anderson 1973]. The plasma density and the peak location of the EIA can be modified by changes of: (1) the transport parallel to magnetic field lines through disturbance neutral winds and diffusion; (2) the loss process due to storm produced composition perturbations; and (3) the transport perpendicular to magnetic field lines due zonal electric field perturbations. During the magnetically quiet time, the electron density and the location of EIA peaks in both hemispheres show prominent seasonal variations. They are generally characterized by (1) in solstice, only the EIA peak in the winter hemisphere remains and a comparatively weak EIA density structure appears in the summer hemisphere, (2) in equinox, two EIA peaks are manifest and the overall electron density is larger than in solstice, (3) the offset of the magnetic equator and the geographic equator also has effects in production of the EIA asymmetry. During magnetic storms, magnetospheric energy and momentum are deposited in the ionosphere/thermosphere through auroral particle precipitation and ionospheric plasma convection driven by electric fields mapped from the magnetosphere. Intense auroral particle precipitation heats the thermosphere, ionizes the neutral gas, and increases the conductivity of the ionosphere. The increased conductivity combined with the magnetospheric electric field produces Joule heating in the ionosphere/thermosphere, which is the major energy source during storms. Heating of the thermosphere drives equatorward wind surges and causes an upwelling at high latitudes which carries heavier neutrals upward and increases the mean molecular mass. In addition to the thermospheric responses, the ionospheric electric field disturbances are observed at middle and low latitudes on different time scales. They result from both prompt penetration of time-varying magnetospheric fields from high latitudes to low latitudes and longer time lasting disturbance wind dynamo effects. In this study, the GPS derived total electron content (TEC), drift measurements from the ROCSAT-I at 600 km, and far ultraviolet airglow measured by the Global Ultraviolet Imager (GUVI) carried aboard the NASA TIMED satellite are utilized for observing the disturbance of the low latitude ionosphere during the magnetic storms. Observations from GPS-TEC often show that the equatorial ionization anomaly (EIA) expanded to much higher latitude with a great enhancement in the density during the early stage of the magnetic storm compared with quiet time. Following the expansion of the EIA, suppression of the EIA is often observed several hours after the storm onset. The derived ExB drifts measured from the Ionospheric Plasma and Electrodynamics Instrument (IPEI) onboard the ROCSAT-I show strong upward/poleward E×B drifts during the EIA expansions and downward/equatorward E×B drifts during the suppression. The [O]/[N2] inferred from the ratio of the 135.6 nm and LBH emissions from the GUVI provides information of storm-time composition perturbations which often result in negative ionospheric effect, i.e. reduced of the plasma density due to the magnetic storm. Theoretical models, the Sheffield University Plasmasphere Ionosphere Model (SUPIM) and the NCAR Thermosphere-Ionosphere Electrodynamic General Circulation Model (TIEGCM), are used to examine the relative importance of the ionospheric drivers in changing the EIA morphology during both magnetically quiet and disturbed periods. Model results show that the summer to winter meridional neutral winds produce the trans-equatorial transport of the plasma, resulting in seasonal asymmetry of the EIA peaks during the magnetically quiet period. Poleward expansion of the EIA peaks and strong increased EIA peak densities observed by the GPS TEC during the early stage of the magnetic storm are simulated and examined by the model. Simulation results show that the storm-produced equatorward meridional neutral wind plays a role in maintaining the ionospheric layer at higher altitude, where the recombination loss is smaller and the plasma is able to accumulate. Combing the upward/poleward E×B drifts with the equatorward neutral wind, poleward expansion of EIA peaks and very high EIA peak densities are simulated by the model during the early stage of the storm. Additionally, new features in the topside ionosphere, such as storm-time electron density hole and density arch are predicted by the model simulations.
Chang, Yao-weng, and 張耀文. "The variation of sporadic E in the ionosphere during the solar eclipse." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/02129349112147019854.
Повний текст джерела國立中央大學
太空科學研究所
98
On July 22 2009, the total solar eclipse was occured, which partially covered about 80% Chung-Li VHF radar. We used the Chung-Li 52MHz VHF radar to observe the 3-m field aligned irregularities(FAI) of sporadic E from July 20 to July 24, 2009 to study the solar eclipse effect on the FAIs. Interferometry technique was used to locate the positions of the FAIs and analyze the mean Doppler velocity, spectral width, and total power of radar returns from the irregularities. The results showed that there are some fluctuations about the mean Doppler velocity during five days. It also showed that the spectral width and total power in the eclipse time are much larger than those in the same time of other days. On the other hand, in this research we also analyze the ionograms recorded by the Chung—Li ionosonde station. Due to the effect of strong magnetic storm occurred in the afternoon on eclipse day, we found that the behavior of the foEs and foF2 are severe perturbed and will discuss and interpret this phenomenon in this thesis. We also compare the parameters data of Chung-Li VHF radar data and ionosonde, including spectral width, the thickness of Es, SNR and foEs, and discuss there differences quantitively and qualitatively.
Han, Feng. "Midlatitude D Region Variations Measured from Broadband Radio Atmospherics." Diss., 2011. http://hdl.handle.net/10161/3856.
Повний текст джерелаThe high power, broadband very low frequency (VLF, 3--30 kHz) and extremely low frequency (ELF, 3--3000 Hz) electromagnetic waves generated by lightning discharges and propagating in the Earth-ionosphere waveguide can be used to measure the average electron density profile of the lower ionosphere (
In order to understand the time scales, magnitudes and sources for the midlatitude nighttime
Based on sferic data similar to those for nighttime, we also measured the daytime
By applying the nighttime and daytime measurement techniques, we also derived the
Dissertation
Young, Matthew Adam. "Meter-scale waves in the E-region Ionosphere: cross-scale coupling and variation with altitude." Thesis, 2019. https://hdl.handle.net/2144/37063.
Повний текст джерелаLu, Shao-Chun, and 呂紹淳. "Observe the variation of the ionosphereic electron density during the earthquakes in Taiwan by using ITS and TWIM data." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/81706060143355267141.
Повний текст джерела國立中央大學
太空科學研究所
98
A network of Ionosphere Tomography System(ITS) have been employed to derive the total electron content (TEC) and/or electron density of the ionosphere above Taiwan and the east Asia region. The TaiWan Ionospheric numerical Model (TWIM) is a numerical model of global ionospheric electron density ,which provides critical frequency , peak density height, and scale height globally for layers D , E , and F . In 2009, there are five earthquakes (M≧6.0) occurred in Taiwan. An analysis has revealed that the VTEC difference between ITS and TWIM data surrounding the epicenters of which events decreased or increased abnormally before the earthquakes.
"Magnetic field line connection between the ionosphere and the magnetosphere -Auroral activity and relevant magnetic field variations at geosynchronous orbit-." Thesis, 1992. http://hdl.handle.net/2237/6624.
Повний текст джерелаNishitani, Nozomu, and 望. 西谷. "Magnetic field line connection between the ionosphere and the magnetosphere -Auroral activity and relevant magnetic field variations at geosynchronous orbit-." Thesis, 1992. http://hdl.handle.net/2237/6624.
Повний текст джерела