大区域似大地水准面模型的建立方法研究

在充分研究现有几何方法确定局域似大地水准面的基础上,根据独立网内点间高程异常差的不变性和独立网间大地高起算基准面与WGS84椭球面的平行性,提出通过两步处理,获得大区域连续似大地水准面的思想和方法,即首先统一相邻两个独立GPS网大地高起算基准面,然后再利用几何方法确定大区域似大地水准面。该方法在长江口北岸得到了很好的验证,并取得了比较理想的精度。

Determination of a Quasi-geoid in Large Region with Datum of Continuous GPS Networks

Due to the inconsistency of geodetic-height datum between two adjacent GPS networks,there exists a height-anomaly difference in same GPS point lied the common area of the two networks.The difference results in unable building a quasi-geoid in large-region with these historic GPS-net data.In order to solve the problem,two methods are studied in detail.One is unifying vertical datum;the other is building height-anomaly difference model.For the first,according to the theory of 3-dimension unconstrained adjustment,the two height anomalies of a GPS/leveling point in adjacent GPS networks and the geoid models established respectively in different GPS networks,a geoid model in large-region is constructed finally.For the second,using the way to unify vertical datum in adjacent GPS network,integrating the stability of height-anomaly difference between two points,firstly the height-anomaly difference of each point relevant to the height anomaly of a given GPS/leveling point is calculated.Then,build a model of height-anomaly difference with a polynomial function is built.In virtue of the polynomial function and the given GPS/leveling point,the height anomaly of any GPS point in the GPS network can be calculated.The two methods are tested with 3 historic GPS-net data in north shore of Changjiang estuary,and ±4 cm of root of mean square is acquired.