采用几何与重力联合方法可确定大地水准面,但需要重力数据、DEM等,数据处理方法复杂,大地水准面精化周期较长。经分析, EGM96地球重力场模型的长、中波精度较高,其区域重力异常的相对值比较精确,可作为区域似大地水准面精化的参考地球重力场模型,区域GPS/水准的最大综合影响为±3.8 cm,区域似大地水准面的精化模型可达到±5 cm。结合湖北省四湖流域综合治理工程的GPS水准数据,在缺少重力数据的条件下,基于地球重力场模型剩余的高程异常,分别采用多面函数法和二次曲面法进行“剩余高程异常”的拟合,对两种拟合方法进行了比较,提出了核函数结点的选取准则。结果表明：采用多面函数法可得到厘米级区域似大地水准面,适合于数千平方千米的厘米级区域大地水准面的确定,且提出的方法较易实施。%The geoid can be determined by combination of geometry and earth gravity method; however, the gravity data and DEM are needed and the data process method is complicated and refinement time is long. Through analysis, the precision of long and middle wave in earth gravity field model EGM 96 are high and the relative value of gravity anomaly in this region is accurate, which can be used as referenced gravity field model for refinement of quasi-geoid. Aiming at the GPS leveling data in the com-prehensive regulation program for 4-lake area in Hubei Province and based on residual elevation anomaly of earth gravity model, the fitting for residual elevation anomaly is carried out by multi-surface function method and quadric surface method respective-ly, in the absence of gravity data. Based on analysis of the two methods, the selection criterion of core function is proposed. The results show that the multi-surface method could provide quasi-geoid for area of thousands of square kilometers with accuracy of centimeters rank, and its advantage is of easier workability.
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