格尔木市高精度数字高程基准模型研究

大地水准面（数字高程基准）为国家高程基准的建立与维持提供了全新的思路。然而，受限于地形、重力数据等原因，高原地区高精度数字高程基准模型的建立一直是大地测量领域的难题。本文以格尔木地区为例，探讨了高原地区高精度数字高程基准模型的建立方法。首先，基于重力和地形数据，由第二类Helmert凝集法计算了格尔木重力似大地水准面。在计算中，考虑到高原地形对大地水准面模型的影响，采用了7.5″×7.5″分辨率和高精度的地形数据来恢复大地水准面短波部分的方法，以提高似大地水准面的精度。然后，利用球冠谐调和分析方法将GNSS水准与重力似大地水准面联合，建立了格尔木高精度数字高程基准模型。与实测的67个高精度GNSS水准资料比较，重力似大地水准面的外符合精度为3.0 cm，数字高程基准模型的内符合精度为2.0 cm。

Research on the establishment of digital height datum in Golmud

Geoid (digital height datum) provides a new way for the establishment and maintenance of national height datums. However, limited by the terrain and gravity data, the establishment of digital height datum with a high precision on plateau has always been a difficult problem in the field of geodesy. Taking Golmud as an example, we discuss the establishment method of precise digital height datum in plateau area. Firstly, based on gravity data and topographic data, we determine the gravity geoid in Golmud through the Helmert's second condensation method. In the computation, to improve the accuracy of gravity geoid on plateau, the topographic data with high resolution and high precision is used to recovery the short wave of the geoid. Then, the digital height datum of Golmud is established through aligning the gravity geoid to the National Vertical Datum 1985 by a spherical cap harmonic method. Compared with 67 GNSS/leveling points independently, the accuracy of the determined gravity geoid is 3.0 cm, the corresponding precision of digital height datum of Golmud is 2.0 cm.