Chao Dingbo

A preliminary study on the establishment of ocean tide models over the South China Sea from T/P altimetry

On the basis of the characteristic of the perfect spatial distribution of the T/P altimeter data, a spatial harmonic tidal analysis is performed, which transfers tidal harmonic constantsH andg of each constituent into a pair of parameters: the cosine part U and sine partV. And each part is expanded into a polynomial. The polynomial coefficients are estimated with altimeter data upon the least squares criteria. Thus the models of principal tidal waves in the South China Sea are established. 72 cycles of T/P data from cycle 11 through 82 are included in the calculation. The models are evaluated with different approaches and data set. The conclusions are that the tide modes can provide partial tide amplitudes with 3 cm accuracy, and that phase lags deviation of those tides with amplitude large than 10 cm are within ±10°.

Bathymetric inversion of South China Sea from satellite altimetry data

This paper focuses on the study of ocean bathymetric inversion from satellite altimeter data by using FFT technique. In this study, the free-air gravity anomalies over the South China Sea are determined by the satellite altimeter data of GEOSAT, ERS-1, ERS-2 and T/P. And the 2.5′×2.5′ bathymetry model in South China Sea is calculated from the gravity anomalies with the inversion model given. After the analysis of the inversion and the comparison between the results, some conclusions can be drawn.

APPLICATION OF THE HARTLEY TRANSFORM IN THE COMPUTATION OF THE GEOID IN CHINA

ABSTRACT This paper presents a method for the computation of the Stokes formula using the Fast Hartley Transform CFHT) techniques. The algorithm is most suitable for the computation of real sequence transform, while the Fast Fourier Transform (FFT) techniques are more suitable for the computa ton of complex sequence transform. A method of spherical coordinate transformation is presented in this paper. By this method the errors, which are due to the approximate term in the convolution of Stokes formula, can be effectively eliminated. Some numerical tests are given. By a comparison with both FFT techniques and numerical integration method, the results show that the resulting values of geoidal undulations by FHT techniques are almost the same as by FFT techniques, and the computational speed of FHT techniques is about two times faster than that of FFT techniques.