Abstract: Time series of vertical displacements obtained from continuous GPS observation at fiducial stations in Crustal Movement Observation Network of China, from September 1999 to March 2004 are introduced with discussions on the selection of datum definition and analysis of the general characteristics of vertical displacements at fiducial stations. A group of 6 stable stations in the east part of China with the same variation pattern and small annual vertical displacement velocities are used in datum definition for vertical displacement time series. Results of calculation show that the accuracy for weekly solutions at a station is about 3mm. Compared to the annual horizontal displacement velocities at the fiducial stations, the annual vertical displacement velocities are rather low almost at all stations. In comparison to the time series of horizontal displacement, the time series of vertical displacement show very significant variations of annual period with magnitudes of 20～50mm. The annual variations in vertical displacement at most fiducial stations in west China show significant correlation with earth rotation and are in agreement with conservation of the momentum of earth rotation. It would be worthwhile to make comprehensive studies on the vertical displacement at fiducial stations and related subjects.

Key words: GPS, fiducial station, time series, vertical displacement, datum definition for displacements

摘要： 利用1998年9月至2004年3月上旬中国地壳运动观测网络基准站GPS连续观测结果所获得的垂直位移时间序列,讨论了基准的选择,分析了基准站垂直位移的特点。取中国东部一组垂直位移变化形态基本一致、年速率较小的6个基准站作为垂直位移时间序列的基准。计算结果表明,每周的垂直位移解的精度可达3mm。与基准站的水平位移年速率相比,垂直位移年速率普遍较低;而与基准站的水平位移时间序列相比,一些基准站的垂直位移时间序列有非常显著的年周期变化,幅度达20～50mm。中国大陆西部基准站的年周期变化与地球自转有明显的相关性,并且符合地球自转守恒。基准站垂直位移的变化值得多方面深入研究。

关键词: GPS, 基准站, 时间序列, 垂直位移, 位移基准