Studies On Antarctic GNSS Precise Positioning

At the end of1980s, GPS began to be used in the research of geodesy in the polar region.With the mature development of GNSS technology, it has been more and more widely used inthe south and north poles during nearly10years. Precise point positioning (PPP) has becomeone of the most widely used technologies in GPS field because of its efficient work, highpositioning precision and low cost. As the hot spot of studying geodynamics, the Antarcticarea involves glaciers melting and sea level fluctuation. Therefore, it has special significanceto study the Antarctic GNSS precise positioning. Moreover, the satellites coverage andpositioning environment in pole region are different from low-latitude areas. Based on abovecharacteristics, some issues on the Antarctic GNSS precise positioning are studied in thisthesis, mainly including:1. The GPS positioning in Antarctic region has different characteristics with those in theinternal continent. Comparing with the Asian internal continent (e.g. Wuhan), more satellitesare visible so that lower PDOP of the polar regional GNSS positioning can be achieved.However, the VDOP in the polar region is weaker because of lacking of satellites with highelevation angles.2. The important significance of the Beidou Compass system for the Antarctic survey isquantitatively studied. Simulation result shows, comparing with using a single navigationsystem, that using Compass and GPS combined system may raise the positioning precision upto43%(in case of the elevation cut-off angle is15degrees).3. Based on the measured airborne kinematic data and static reference station data, theprecision of Antarctic airborne kinematic positioning has been analyzed. Results show that theairborne kinematic positioning can obtain a precision of sub-decimeter by using precise pointpositioning technology in Antarctic region. Therefore the development of precise pointpositioning technology provides a new solution for long distance and high-precision postairborne GPS kinematic positioning.4. In case the satellites elevation angles in Antarctic stations are lower, the troposphericdelay which will be highly influenced by satellites with lower angles in Antarctic GPSpositioning has been analyzed. Through using correcting model based on real meteorological data, the positioning precision could be improved with the same elevation cut-off angle;alternatively, for obtaining the same positioning precision using above method, the elevationcut-off angle could be reduced from15degrees to5degrees. In this way, more lowerelevational observations can be used and the redundancy of observations are increasedwithout losing the positioning precision in Antarctic area.5. The variation of ionospheric delay in Antarctic region and the impact of ionosphericsecond-order delay on Antarctic GPS positioning have been analyzed. Results show, TEC inAntarctic region has frequent fluctuation during the day and the maximum TEC in thedaytime changes more intensely than in the mid-latitude area. In Antarctic region, theinfluence of ionospheric second-order delay on GPS positioning can achieve a magnitude ofcm in summer. Moreover, the regional ionosphere model RIM has been established. Resultsshow, in Antarctic region the positioning precision of RIM is more superior than GlobalIonosphere Maps GIM to some extent.