Study Of Sporadic E Layers And Ionospheric Inflence Of Heyuan Earthquakes Based On The Occultation Data Observed By FY-3C And COSMIC

Sporadic E layer is a kind of unstable structure, which has a very high electron density. The uneven structure is very easy to have a serious impact on the communication system, navigation system. More than half a century, Sporadic E layer has been extensively researchedby the domestic and foreign scholars using the ground detection means,like traditional ionospheric altimeter, the incoherent scattering radar, high frequency radar and VHF radar. but for the emergence reason,change factors and forming mechanism are not perfect analysis.With the GPS technology matures, A new ionospheric sounding technology has emerged-- Radio Occultation technique. And compared with the traditional ground detection, the new one can observe withhigh resolution and in all-weather. And it can not affect by the climate, geographical conditions and other factors.Radio occultation technology not only can observe the global ionosphere and the earth’s atmosphere, but also brings new breakthrough for studying the ionospheric changes in earthquake. In the third chapter, using radio occultation technique of FY-3C satellite and COSMIC system occultation data, analysis the variation characteristics of Es in the global scope. In the fourth chapter, using TEC data provided by ten GPS-TEC monitoring stationin the eastern region of Guangdong Province, and the electron density profile data over Heyuan provided by COSMIC system, analyzes theinfluenceon the ionosphere of 2012 two earthquake in Heyuan. The main conclusions of this paper are as following:1, Using the GPS radio occultation data during June 2014 and May 2015 that are provided by FY-3C polar-orbiting satellites, the disturbances ofSNR with sampling frequency of 50 HzC / A code on a global scale are statistically analyzed,and the variation characteristics of sporadic E layers with the geographic latitude and local time and the height are also studied.The results show that: the disturbance strength of sporadic E layer at mid-latitudes in the summer hemisphere area is far greater than that at the same latitudes in the winter hemisphere, and that the disturbances of the sporadic E layers near the latitude of 40 °are significantly enhanced. In addition, at 100 km height, the disturbances of Es layers reach the peaks at 10:00LT and 22:00LT. The occurrence rates of sporadic E in summer hemisphere is significantly higher than that in the winter hemisphere.2, Using the radio occultation data of June 2014 and December 2015 that are provided byCOSMICsystem,the variation characteristics of the Es layer with the geographic latitude and local time and the height are analyzed. The results showed that The results observed by FY-3C satellite are consistent with those observed by the COSMIC system. Therefore, the occultation data of FY-3C satellite could be used to study ionospheric sporadic E layers.3, Using TEC data of 2012 February 1 to 22 provided by ten GPS-TEC monitoring station in the region of South China, analyzes time series of TEC during 2012 two earthquake in Heyuan.The results showed that TEC perturbations including negative anomalies as well as positive anomalies occurred15 days before two Heyuan earthquakes, indicating moderate magnitude earthquakes with less destructibility being able to trigger perturbations in the ionosphere. And the TEC perturbations of the ionosphere monitored from ten GPS receiver stations were lower than that from four GPS receiver stations within thepreparation zone of earthquake, indicating the validity of the Dobrovolsky’s formula for estimating dimensions of the earthquake preparation zone.4, Using the electron density profile data of 2012 February 1 to 25 over Heyuan provided by COSMIC system, analyzes thevariations of ionosphere during 2012 two earthquake in Heyuan, results show thatthe peak electron density ofF2 layer decreases obviously on February 11 th, and electron density has gradually regained on February19 th, the decrease of NmF2 before earthquake is likely to be the impact of the Heyuan earthquake on the ionospheric. And the results observed by COSMIC radio occultation system are consistent with those observed by the GPS-TEC. The researchalso shows that using radio occultation data is credible to study the effects of earthquake on the ionosphere.