Studies On Seasonal Vertical Crustal Movement In Chinese Mainland

This thesis is undertaken in view of studying the characteristics of seasonal vertical crustal movenent of GPS fiducial stations in Chinese mainland, based on the theory of an elastic Earth's response to surface loads, such as atmospheric loading, non-tidal oceanic loading and continental hydrological loading. The time series of loading effects on crustal vertical displacements are obtained. Then we present the time series of vertical motions of the same sites with the comprehensive analysis of the latest GPS data of Crustal Movement Observation Network of China (CMONOC), set up in 1999.The main points of this thesis are:The introduction discusses, generally, the necessity and methods of the studies on the vertical crustal movement, as well as the status of such studies home and abroad. In chapter 1, the earth' surface loading theory is introduced; in chapter 2, the stable recurrence relations are shown how to the calculate higher spherical harmonic coefficients, and the use of Fast Fourier Transform is proved to be fairly efficient to compute these coefficients as well; in chapter 3, the climatology datasets as well as GPS observation data and preprocessed results are introduced; in chapter 4, the seasonal vertical displacements are estimated for each surface load as well as for the total contribution. A comparison is performed for each station between the GPS-derived results and those of geophysical fluid loadingeffects, which shows a good agreement for most stations. Finally, the conclusion and prospect is presented.The main innovations of this thesis are: the surface load data is the latest and comprehensive up to now; it is the first to perform such a systematic study on seasonal vertical crustal displacements caused by surface loads at GPS fiducial stations in Chinese mainland. The results in this paper will be helpful to raise the height accuracy of GPS measurements of CMONOC.