Calculating Stationary Sea Surface Topography of Coastal Area with Altimeter and Oceanographic Data

The method that hydrodynamic models are reconciled with observation,e.g.altimeter and oceanographic data,is called as data assimilation. Calculating coastal stationary sea surface topography with altimeter and oceanographic data,called as combination problem for short,is a technique of data assimilation,which is one of the front research area in altimetry. In this paper,the basic equations are integrated in the vertical direction with approximation of Boussinesq and quasi-static on the basis equations of liquid dynamics. And then an elevation-mode of steady current and its solid boundary condition are derived with a reference geoid as reference surface. Observation equations are formed using finite difference method from the elevation-mode of steady current and its solid boundary condition with stationary sea surface topography as observation value and the square root of onflow friction coefficient as parameter,and the combination problem is solved with parameter adjustment. In the end,stationary sea surface topography of Eastern China Sea,in 22°N~41°N and 116°E~131°E,is calculated with T/P and ERS-2 altimeter and oceanographic data.It comes to the following conclutions from this paper: (1) Sea bottom relief and sea density field are main influence on stationary sea surface topography.(2) The reference geoid error the wavelength of which is longer than size of the selected area can not be eliminated by the parameter adjustment because the observation equations are finite difference of stationary sea surface topography. Hence,reference geoid is used to fix stationary sea surface topography the wavelength of which is longer than size of the selected area in this paper.(3) There is a denseness isoline whirlpool of stationary sea surface topography around entrance of the Changjiang River. The isoline near Liuqiu archipelago are disorder. There is a denseness isoline southwest Liuqiu archipelago,which could be relative with Taiwan Kroshio.