关键词: GPS, 基准站, 时间序列, 垂直位移, 位移基准

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