Study On The Data Processing For High Precision Satellite Radar Altimeter

Satellite radar altimeter is an important kind of ocean microwave remote sensor which can be used to measure the sea surface height(SSH), significant wave height(SWH) and backscattering coefficient(0s). The further inversion results of the measurements can be applied to ocean geophysics, marine dynamics, climate and environment, sea ice monitoring, etc. Synthetic Aperture Radar Altimeter(SARA) is a new type of high precision radar altimeter which adopts the synthetic aperture technique. So the SARA can improve the measurement precision and resolution compared with the Conventional Radar Altimeter(CRA).In this paper, the data processing techniques of the CRA and the SARA are comparatively studied, the two kinds of altimeter are simulated, and the two modes data of an airborne experiment is processed. The results of theoretical analysis, simulations and the airborne experiment all show that the SARA can obtain more precise measurements than the CRA.For the CRA, a new echo model which is suitable for larger range of antenna mispointing angle is derived. The retracking algorithm and its precision are studied as well. In the case of the SARA, a new Range Migration Correction Algorithm(RMCA) which can correct not only the slant range error but also the residual errors caused by satellite movement is proposed, then the method of matching the sub-look with the footprint strip is studied, and a recorrection method among different bursts is proposed. Also, the echo model, retracking algorithm and precision of SARA are studied in detail.The main contributions and innovations of this paper are as follows.1. A comparative study on the data processing techniques between the CRA and SARA is carried out. The two sorts of radar altimeter system are simulated, and both of the CRA and SARA mode data of an airbone experiment is processed. All of the results above prove that the SARA is more precise than the CRA.2. For the CRA, a new echo model suitable for larger range of mispointing angle is derived. By the new model more exact results of the HY-2A altimeter can be obtained.3. For the SARA, a new RMCA is proposed which can correct not only the slant range error but also the residual error caused by satellite movement.4. For the SARA, the method of matching the sub-look with the footprint strip is studied, and a recorrection method among different bursts is proposed.