LOW LATITUDE IONOSPHERIC MODELING
OVER INDONESIA FROM GPS DATA
NIM : 35104002
Promotor : Prof. Dr. Ir. Hasanuddin Zaenal Abidin MSc.
Co-Promotor : Prof. The Houw Liong Ph.D.
Co-Promotor : Dr. Ir. Wedyanto Kuntjoro MSc.
Ionosphere affects electromagnetic waves used in GPS system. Total time transmission of GPS signal propagation through ionosphere from satellite to receiver consist ionospheric delay time of transmission. The ionospheric delay depend to the ionospheric total electron content (TEC) and GPS signal frequency.
From dual frequency GPS receiver data can be derivied the ionospheric TEC value by using combination of GPS code and phase, then the TEC data can be used for developing low latitude ionospheric model and method of earthquake precursors revealing.
The ionospheric models are including daily and monthly ionospheric model. The daily local ionosphric model is developed from single GPS station. The daily regional ionospheric model is developed from several GPS station in Indonesian sector. The monthly ionospheric model have been developed from GPS data in Indonesian sector. The monthly ionospheric model assume that at same local time and latitude the TEC value have no dependent to longitude change in Indonesian sector. Local time variation of TEC is estimated by using Fourier series, latitudinal variation of model is expressed by using polynomial function and ionospheric response to solar activity is assumed linear.
The monthly ionospheric model can be used for daily ionospheric prediction by daily updating of the model by using daily data of TEC derived from GPS data. Daily updating of the monthly model is examined during geomagnetic storm and ionospheric precursors of large earthquake and resulting the TEC prediction more accurate rather than monthly ionospheric model. The daily update of monthly ionospheric model give contribution for increasing accuration of ionospheric model by using daily ionospheric index.
The daily ionospheric index is also can be used for ionospheric anomaly detection related to earthquake precursors or geomagnetic storms. Several earthquake precursors in ionospheric parameter at low latitude can be revealed by using S index and ionospheric tidal activity index. Mechanism of ionospheric precursor caused by gravity anomaly before earthquake is a alternative hypothesis and required clarification by using local earth gravity.
Key words: GPS, ionosphere, low latitude, Indonesia sector, model, ionospheric index, anomaly, earthquake precursor.