Research On Tide Dynamic Methods Of Bathymetric Inversion Based On Altimeter Data

Sea depth is the distance between the bottom to the mean surface of the ocean, which is closely related with the benthal topography and geomorphology. Sea depth data play a pivotal role in different disciplines’ researches and applied fields as fundamental data. Therefore, researches on methods of bathymetry are always key issues in studies of geography. However, there are many problems exsiting in traditional bathymetry, including expensive costs, time and labor consuming problem, long measurement and calculation period, low efficiency and limitations on applicable waters because of the bathymetry methods or data sources. This kind of situation impels researchers of different disciplines to explore new methods of bathymetry constantly with expectation of finding a better way.With the rapid development of space technology, altimeter carried by satellite can provide many years’ time series data of sea surface height, which can convert unknown information of sea surface into known. For this reason, this paper put forward a tide dynamic method of bathymetry inversion based on altimeter data. This method is a brand-new exploration and a good supplement to bathymetry.This paper studies on method of tide harmonic analysis based on many years’ time series data of sea surface height. It implements tide harmonic analysis to south sea of China based on altimeter data of T/P and Jason-1/2 satellite series. The results of tide harmonic analysis was compared with the harmonic constants of two main constituent (M2 and K1) of 132 tide stations in British tide table. The verification result suggests that the results of harmonic analysis nearshore are reasonable. And the verification result in deep sea is relatively more accurate.Because of the complex sea state and the tide movement nearshore, the accuracy of harmonic constants calculated from satellite altimeter data is not high enough. In order to improve the accuracy of harmonic constants nearshore, this paper proposes a way to mix together the tide station data and altimeter data, and uses this mixed data to draw cotidal charts for the four main constituents. This paper draws a conclusion which matches the predecessors’ after analyzing and discussing about the tide movement in south sea of China.Utilizing research idea of inverse problem, this paper put forward a 2-dimensional sea depth inversion method based on tide dynamic theory and designs a series of numerical scheme including discrete method, solution method and definite conditions to ensure the efficiency and stability during the numerical model’s course of calculation.All of the above are the innovation points and core contents of this paper.This paper uses harmonic constants simulated by tide model as data resources of 2-dimension ocean depth inversion model to conduct a numerical experiment. It suggests that the numerical scheme is reasonable after analyzing and discussing the process curve of tide level, velocity and instant depth of water. In the numerical experiment, the accuracy of the results is high, which proves the correctness of the 2-dimension ocean depth inversion model. The actual experiment using altimeter data as data resources has a less accurate result compared with the numerical experiment, which can be attributed to the accuracy of the harmonic constant derived from the altimeter data are not high enough. However, the results of the actual experiment basically meet the expectations, which proves the method of this paper is feasible and practical applicable. It is of significance to be further studied on and potential application prospect.