| Summary: | 碩士 === 國立中央大學 === 太空科學研究所 === 96 === The GPS signals received by high resolution GPS receiver located at Tainan from 2003 to 2007 were analyzed, in which 3-minute scintillation signals of the GPS amplitude variations were employed to estimate S4 index. The elevation angle and trajectory of GPS satellite were both computed to locate the electron density irregularities responsible for the S4 index. Combining satellite orbit projected at 350km and S4 index, the location of the ionospheric irregularities can be identified. The characteristics of the scintillations induced by refractivity fluctuations in troposphere and ionosphere were investigated. We find that the statistical properties of the S4 index originated from troposphere and ionosphere are very different. The ionosphere-originated scintillation generally started to occur in 1 hour after sunset, appeared most frequently just before local midnight, and disappeared by early morning. However, the troposphere-originated scintillation occurred nearly uniformly throughout 24-hour a day.
|
|---|
