Research On Reference Datum Of The Vertical Motion Of The Crust

As a part of global motion, the crustal motion is closely connected with the living and development of human being, since it happens on the Earth's surface. With the development of space technology, the crustal motion has been given enormous attention. Because the reference datums of vertical motion of the Crust are not consistent with each other, the velocities of the same station obtained from all individual analysis centers are different. And the vertical velocities offered by some countries and regions are difficult to be used. It becomes very important to study and develop the reference datum of vertical motion of the Crust with clear physical sense and easy implementation and application, which is valuable in many fields such as geodesy, earthquake, geophysics, and so on. The main work is as follows:1. The vertical crust motion, definitions, realization and establishing of the International Terrestrial Reference Frame and the latest ITRF2005 are reviewed. Then, the global plate motion model is calculated based on ITRF2005.2. The disagreement between geocentric coordinates of the co-located stations measured by GPS and VLBI is derived and then the real accuracy is evaluated.3. The real accuracy of the geocentric coordinate velocities from GPS, VLBI and SLR of the latest ITRF2005 is evaluated and comparisons are made among them. On detecting the crustal motion using space techniques like GPS, VLBI and SLR, the baseline length rate of the co-located stations is computed using the geocentric coordinate velocities determined by the three techniques, and the systematic errors among them is revealed in detecting the crustal motions.4. Three methods to establish the vertical datum of the crustal motion are put forward and investigated, which is the heart of the paper. The systematic errors are calculated between some vertical velocity fields and the reference datum of vertical motion of the Crust, and the reasons for the diversity of systematic errors are analyzed. Firstly, the applicability of the three methods is proved. Secondly, the systematic errors between some vertical velocity fields and the reference datum of vertical motion of the Crust are calculated to make the vertical velocity fields consistent with the reference datum of vertical motion of the Crust. Finally, the reference datums of vertical motion of the Crust that are established based on three different principles are analyzed and compared, and the conclusion were made that the reference datum of vertical motion of the Crust based on SLR has advantages like clear physical sense, easy implementation and application.5. The vertical motion in China is depicted. The reasons why different values occurred between the time series of datum station and the vertical velocity picture by leveling measurement are analyzed. Then the systematic error between the vertical velocity field of China and the vertical datum of the global crustal motion is calculated to unify the reference datum of vertical motion of the Crust of China and the vertical datum of the global crustal motion.