基于FY-3C和COSMIC掩星数据的电离层偶发E层及河源地震电离层影响的研究

发布时间：2018-02-13 19:35

本文关键词： 无线电掩星 FY-3C COSMIC 偶发E层地震影响　出处：《华南理工大学》2016年硕士论文　论文类型：学位论文

【摘要】：偶发E层是一种非稳定出现的不均匀结构,其电子密度特别高且变化随机。这种不均匀结构极易对通信系统、导航系统产生严重影响。半个多世纪以来,国内外的学者们利用传统的电离层测高仪、非相干散射雷达、高频雷达以及甚高频雷达等地基探测手段对偶发E层进行了广泛的研究,但对于其出现原因、变化因素和形成机理等尚未给出完美的解释。随着GPS技术的日益成熟,出现了新的电离层探测技术——无线电掩星技术。与传统的地基探测相比,具有全天候、分辨率高、不受气候和地域条件等因素制约的优点,可以实现对全球范围内电离层和地球大气层的观测,也给研究地震期间电离层的变化带来了新突破。本文第三章利用无线电掩星技术中FY-3C卫星和COSMIC系统的掩星数据,在全球范围内分析Es的变化特征。第四章利用华南地区十个GPS-TEC监测站提供的TEC数据,及COSMIC系统提供的河源上空附近电子密度剖面数据,分析了2012年河源两次地震对电离层的影响。本文主要结论有以下几个方面:1.利用FY-3C极轨卫星提供的2014年6月至2015年5月的GPS无线电掩星数据,统计分析全球范围内抽样频率为50Hz的C/A码SNR扰动情况,进而研究偶发E层随地理纬度、地方时及高度的变化特征,观测结果表明:偶发E层在处于夏季半球中纬地区的扰动强度远远大于处于冬季半球同一纬度地区的扰动强度;偶发E层在纬度40°附近扰动明显增强;此外在E层100km高度附近,Es层在地方时10:00和22:00达到峰值;Es层在夏季半球出现率明显高于冬季半球。2.利用2014年6月和12月COSMIC系统掩星数据分析了Es层随地理纬度、地方时及高度的变化特征,结果表明:FY-3C卫星的掩星观测结果与COSMIC系统的观测结果较一致,可以利用FY-3C卫星的掩星数据研究电离层偶发E层等的变化。3.利用2012年2月1日至22日十个GPS-TEC监测站提供的TEC数据,分析了2012年河源两次地震期间TEC的时间序列,结果表明:河源两次地震前15天TEC出现了扰动,包括负异常和正异常,也表明具有更小破坏性的中等强度的地震,能够触发电离层扰动。此外,十个GPS接收机站监测到的电离层TEC扰动低于地震孕育区内的四个GPS接收机站监测到的电离层TEC扰动,表明Dobrovolsky的公式可以有效性地评估地震孕育区的范围。4.利用2012年2月1日至25日COSMIC提供的河源上空附近电子密度剖面数据,分析了2012年河源两次地震期间电离层变化,结果表明:2月11日F2层峰值电子浓度开始减小,19日电子密度逐渐恢复,地震前NmF2的减小极有可能是河源地震对电离层产生的影响。而COSMIC掩星观测结果与GPS-TEC观测结果相一致,也说明利用掩星数据研究地震对电离层的影响是可信的。
[Abstract]:The accidental E layer is a kind of unstable and uneven structure, whose electron density is especially high and changes are random. This kind of non-uniform structure is easy to have serious influence on the communication system and navigation system. For more than half a century, Scholars at home and abroad have made extensive research on the accidental E layer by traditional ionospheric altimeters, incoherent scattering radar, high frequency radar and very high frequency radar. With the development of GPS technology, a new ionospheric detection technology, radio occultation technology, has emerged. Compared with traditional ground-based exploration, it has all-weather and high resolution. The advantage of being free from factors such as climate and geographical conditions enables observations of the ionosphere and the Earth's atmosphere on a global scale, In the third chapter, we use the occultation data of FY-3C satellite and COSMIC system in radio occultation technology. Chapter 4th uses the TEC data from ten GPS-TEC monitoring stations in South China and the electron density profiles near the river source provided by the COSMIC system. The influence of two earthquakes on the ionosphere in Heyuan region of 2012 is analyzed. The main conclusions of this paper are as follows: 1. Using the GPS radio occultation data from June 2014 to May 2015 provided by the FY-3C polar orbit satellite, The SNR disturbance of C / A code with sampling frequency of 50 Hz worldwide is analyzed statistically, and the variation characteristics of accidental E layer with geographical latitude, local time and height are studied. The results show that the intensity of the occasional E layer in the mid-latitude region of the summer hemisphere is much greater than that in the same latitude region of the winter hemisphere, and the disturbance intensity of the occasional E layer is obviously increased near the latitude of 40 掳. In addition, the occurrence rate of es layer in summer is significantly higher than that in winter hemisphere at 10:00 and 22:00 at 10:00 and 22:00 local time. The occultation data of COSMIC system on June 2014 and December are used to analyze the estrations with geographical latitude. The variation characteristics of local time and altitude show that the occultation observation results of the 1: FY-3C satellite are in good agreement with those of the COSMIC system. The occultation data of FY-3C satellite can be used to study the variation of ionospheric accidental E layer et al. Using the TEC data provided by ten GPS-TEC monitoring stations from February 1st 2012 to 22nd, the time series of TEC during the two earthquakes in Heyuan, 2012, are analyzed. The results show that the disturbance of TEC, including negative anomaly and positive anomaly, occurred 15 days before the Heyuan earthquake, which also indicated that the earthquake with less destructive medium intensity can trigger the ionospheric disturbance. The ionospheric TEC disturbances detected by 10 GPS receiver stations are lower than those detected by four GPS receiver stations in the seismogenic region. The results show that the Dobrovolsky formula can effectively evaluate the range of seismogenic area .4.Using the data of electron density profile near the source from February 1st 2012 to 25th provided by COSMIC, the ionospheric changes during the two earthquakes in the Heyuan area of 2012 are analyzed. The results show that the peak electron concentration in F2 layer began to decrease on February 11th, and the electron density gradually recovered in 19th. The decrease of NmF2 before the earthquake is probably due to the influence of Heyuan earthquake on the ionosphere. The results of COSMIC occultation are consistent with those of GPS-TEC. It also shows that using occultation data to study the effects of earthquakes on the ionosphere is credible.
【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：P352.7;P315.728

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