Geosat Altimeter Data Processing And Accuracy Assessment On The Inversion Of Gravity Anomalies In The South Sea

The satellite altimetry technique has very important meanings for observing all-weather, duplicative and accurate marine information in the worldwide. Using high-precision observations of inversing gravity anomaly is one of important channels to obtain marine gravity anomaly. The accuracy of observed values and the accuracy assessment of inversing gravity anomaly affect directly the determination of high-precision the marine gravity anomalies.Focusing on the shortcomings of complexity in current crossover adjustment process and imperfect of error models, the error model has been improved in the crossover adjustment method in this thesis. This error model is considering the radial orbit error while taking a variety of composite effects produced by the interruption of systematic errors into account. It includes not only the linear part of the error but also the periodical part of it. At the same time, according to the different data points on each track, the error model of different parameters is chosen, and crossover adjustment is done by the use of conditional adjustment. The results show that the calculation process of this method is simple without rank deficient, and the accuracy of the adjustment is similar with the results obtained from traditional methods. It improves the stability and reliability of the results. It can be seen that conditional adjustment based on improving error models is more practical.At present, accuracy assessment on the inversion of gravity anomalies with the boat test data is just to suggest the root mean square error simply, without considering the characteristics of gravity anomaly distribution. In order to get more detailed assessment on inversion precision of gravity anomalies in some regions of South Sea, and discuss whether satellite altimetry inversing gravity anomaly can fill the blank areas where the actual boat test data can't be measured or not, this thesis evaluates the precision of inversing gravity anomalies with the comparative methods of overall method and zoning classification. The overall comparative results indicate that the accuracy of inversing gravity anomalies measured by the satellite altimetry is 7.42 , a high precision. The result is credible. High-precision gravity anomaly data mostly is concentrated from -30 mGal to 30 mGal . The comparative results of the classification coincide with the actual condition according to the definition of gravity anomaly. It shows that the earth's gravity field itself has a great impact on the accuracy of satellite altimetry. The south and the north areas of Zhongsha Islands blank area are selected to compare partitively, and the inversion accuracy of the two areas is higher than that of the whole area. It shows that the precision inversed by satellite altimetry is lower near Zhongsha Islands, so the feasibility of filling the blank areas which the actual boat test data can't measure with satellite altimetry inversing gravity anomaly is to be further explored.