中文摘要：

利用级数展开思想，将地面测站重力位沿径向展开至大地水准面重力位并取至二阶项，从而间接获得W0，按照此思想采用波罗的海水准测量工程（1997—04）中GPS测站的数据开展了确定W0的实验。计算结果表明，EGM2008模型和WGD2000椭球谐模型（360阶次）在重力位一阶项的数值非常接近，其差在10-3量级，EGM2008模型获得的二阶项为10-5量级，其影响可以忽略。在测站地心坐标不变时，高程数据的变化对w。的确定影响较大，因此，准确测量测站的高程是确定W0的关键。利用5组GPS测站数据以及前360阶的EGM2008模型最终得到波罗的海区域大地水准面重力位W0值为62636857．23±0．48m2·s-2。

英文摘要：

Gravitational potential can be expressed as a mathematical series, in which the first section is geoid potential-W0. This method was used to determine the Baltic Sea geoid poten- tial by using the GPS station data（1997-04）. The results show that the first rank term com- puted by EGM2008 is almost equal to the results computed by WGD2000 （complete to degree and order 360）while the difference is about a quantity of 10-3. The second rank term has a quantity of 10-Sand can be omitted. In the case of changeless geocentric coordinates, the determination of W0 is largely affected by changing height data, so it is important to accurately determine the height of the GPS station. The W0 value（62636857.23±0.48m2·s-2） of Baltic sea study site is obtained by using five set of GPS stations and an EGM2008 model with degree and order of 360.