Seismic Ionospheric Anomalies Research Base On Ground-based GPS Data

Research of seismic ionospheric anomalies originated in the Alaska earthquake in1960s, and for decades it had been studied by many scholars in the relevant field. Withthe GPS civilianized, some scholars have found out GPS is better than traditionalionosonde sounder to monitor the ionosphere in detecting height, time and spatialresolution, and therefore introduced it into the study of seismic ionospheric anomalies.This thesis systematically studied the methodology of how to useground-based GPSdata to observe seismic ionospheric anomalies, including:1) Description of the coupling mechanism between the earthquake and theonosphere, whichincludes what the earthquake is and its birth process, thestructure of ionospheric layers, TEC, disturbance anomalies and magneticdisturbances equatorial anomalies, and summary of several explanations tothe coupling mechanism of seismic ionosphere.2) Research of TEC solver process, which includes the pseudo-range and carrierphase observation equation, the concept of shell model ionosphere, GPS signaldelay in the ionosphere, dual frequency pseudorange and carrier phase solving,cycle slip detectionby TurboEdit method, carrier phase smoothed pseudorange,puncture point calculation, the establishment of GPS hardware delay correctionand regional models, the algorithm of solving TEC base on GPS and so on.3) Research of VTEC time series forecasting model, whichincludes the concept oftime series and stationary time series, time series modeling steps, pretreatmentof non-stationary time series analysis, and VTEC forecasting cases.4) Analysis of typical earthquake cases, which includes the analytical methods ofearthquake, i.e. data preparation and processing, the abnormal analyticalmethods and other background factors on the ionosphere. The2011Great EastJapan Earthquake was analyzed on ground-based GPS data and the2013Lushan Earthquake was analyzed on GIM data, in both of which abnormalitieshappens.5) Statistical analysis of regional earthquake collection, whichstudied33earthquakes with Mw≥6.5in the years2003-2013in Japan based on IGS GPSdata. Revevant methods metioned above were used to analyze statistical results and conclusions could be draw as follows:1Anomalies usually appear a few days before or after the earthquake, andmove to the peak period at local time during the day in the afternoon.Thehigher the magnitude, the higher frequency of anomalies and the longer theduration;2Disturbances occurs a few hours after the earthquake in some highermagnitude earthquakes,but not in most of cases.3Abnormal area is found a few days before or after the earthquake,characterized byconjugate distribution along the magnetic equator, movingand disappearing gradually, but the initial phase does not always coincidewith the epicenter.Through research intothe relevant earthquakes in the thesis, it is indicated that it isfeasible to study the ionospheric anomalies based on ground-based GPS, and thereexists a definite relationship between the ionospheric anomalies and earthquakes.However, it is uneasy to determine the coupling relationship between the two, and along-term and large scale monitoring is required in the future, with an aim to come tothe final conclusion on the basis of a large enough sample.