Zero-difference Kinematic Orbit Determination Of GRACE Satellite

LEO satellites have been widely used in the fields of Earth gravity field inversion,ocean monitoring,topographic mapping,etc.These applications require high-precision satellite orbit information.On-board GPS technology is widely used because of its all-weather,continuous,autonomous and high-orbiting quality.In this paper,the centimeter kinematic orbit is calculated by the GRACE satellite on-board data with batch least squares method,compared with the JPL reduced-dynamic orbit,and analyzes the influence of each error in the pre-processing on the orbit determination.The main works and contributions are as follows:1 ? The research background and significance of using orbit determination data for low-orbit satellites are introduced in this paper,and the development of on-board GPS technology and the research status of three satellite orbit determination methods are summarized.2?This thesis Introduce the common time systems and coordinate systems,and realize the conversion of common coordinate systems and time systems by using SOFA software.3?The basic principles and mathematical models of the zero-difference kinematics orbit determination of low-orbit satellites are introduced in detail,as well as the error sources and corrective measures in the orbit determination of on-board GPS LEO satellites.4?The Blewitt method and its improved cycle slip detection methods were introduced and these methods were compared in thesis.The results show that the combination of FBMWA and STPIR can detect the cycle slip more accurately.5?Analyze the impact of each error correction on the orbit determination results.The results show that when the orbit interpolation uses 9th-order Lagrange interpolation,the interpolation error reaches the centimeter level.the clock interpolation has centimeter level and decimeter level,and the CODE clock products are better than the IGS clock products.Setting the appropriate cut-off height angle can ensure that not too many epochs are removed and good results are obtained.the influence of phase center offset on the orbit determination result is decimeter level.the relativistic effects have an influence on the orbit determination result of 5 to 10 meters.6 ? Using the combination of no ionosphere,the combined ambiguity is set to an unknown number,and iteratively solved by the batch least squares method.A centimeter-level GRACE satellite orbit is obtained and compared with the JPL reference orbit.Calculate the orbit difference for a month.The average accuracy(RMS)of GRACE-A satellites in three directions is 4.13 cm,4.51 cm,4.34 cm.And the average accuracy(RMS)of GRACE-B satellites in three directions is 3.89 cm,3.80 cm,4.40 cm.7?The spatial distribution characteristics and influencing factors of GRACE satellite geometric orbits as follow.The spatial distribution of GRACE satellite geometric orbit presents three characteristics because of the influence of HDOP,visible satellite number and GPS monitoring station distribution.The first is that the orbital accuracy in ocean area is better than in the terrestrial area.The second is that the overall accuracy distribution shows that the low-latitude part is lower than the high-latitude part,and the third is that the accuracy of the 60 degree latitude is higher than that of the Arctic region.