The Fitting of GPS-Level and Gravity Quasigeoid Based on Adaptive Collocation

The efficient fitting way is the key to improve the accuracy of refining quasigeoid during the refinement.Collocation is used to control the influence of systematic errors in the paper for there are systematic errors in the difference between GPS/level and gravity quasigeoid.For covariance matrices of the signal vector and the observational noise are not harmonic in least square collocation,the covariance matrices are adaptively adjusted to approach the true with estimation of variance components in order to improve the accuracy of quasigeoid.An example of one eastern city with the area of 20 000 km² is given.It is shown that least square collocation and adaptive least square collocation can heighten the reliability of fitting,make the accuracy of quasigeoid higher and get the 1cm accuracy quasigeoid of large area in China.