1985国家高程基准相对于大地水准面的垂直偏差

The Origin Vertical Shift of National Height Datum 1985 with respect to the Geoidal Surface

局部高程基准通常由一个 (或多个 )验潮站所测的当地平均海面确定。由于海面地形的客观存在 ,人们已经认识到当地平均海面与大地水准面的差异可能达 2m之多。为了获得这一垂直偏差 ,很有必要确定当地平均海面和全球大地水准面上的重力位值。提出了利用全球重力场模型和GPS/水准资料计算局部高程基准相对全球大地水准面垂直偏差的 2种不同方法。我国目前采用的 1 985国家高程基准 ,由青岛验潮站所处黄海平均海面 1 95 2～ 1 979年的验潮记录计算得到。利用全球重力场模型和分布全国大陆范围的GPS/水准数据 ,计算了 1 985高程基准与大地水准面的垂直偏差。结果表明 1 985国家高程基准点的重力位值为( 62 63685 3.40± 0 .1 3)m2 s- 2 ,这比重力位W0 =( 62 63685 6.0± 0 .5 )m2 s- 2 隐含的大地水准面高 ( 0 .2 6± 0 .0 5 )m。

The local vertical datum was traditionally defined by the local mean sea level at a tide gauge or at a group of tide gauges. It is realized that the local mean sea level has normally a departure from the geoid possibly up to two meters. In order to evaluate the vertical offset, it is essential to know the geopotential of the mean sea level and of the geoid as well. In this paper we develop models to compute the geopotential of an equipotential surface in terms of the geopotential coefficient model, e.g. EGM96 and DQM99A. We employ the developed models in conjunction with the GPS/leveling data, to calculate the offset of the National Vertical Datum 1985 defined by the mean sea level of Yellow Sea at the Dagang tide gauge in Qingdao city in terms of the 1952～1979 tide gauge records. The results show that the geopotential of the local mean sea level is equal to (62 636 853.40±0.13)m 2s -2 and thus the National Vertical Datum 1985 surface is (0.26±0.05)m above the geoid realized by the geopotential value of W 0=(62 636 856.0±0.5)m 2s -2 .