Waveform Reconstruction And Validation Of Inshore On HY-2 Airborne Radar Altimeter

With the gradual maturation of satellite altimetry, satellite radar altimeter as a payload has been carried on many satellites. Satellite radar altimeters such as TOPEX/POSEIDON, Jason-1/2, ERS-1/2 and ENVISAT etc. have become important tools for the study of ocean dynamic environment. However due to the influences of the islands or land on radar altimeter signals in the coastal area, data acquisition and correction along the coast are not as accurate as that on the ocean. And this often leads to unusable inshore data. In order to obtain accurate sea surface height (SSH) and significant wave height (SWH) and to improve the usability of acquired data, it becomes necessary to reconstruct altimeter waveform.The first Chinese ocean dynamic environment satellite, namely HY-2 (Haiyang-2 satellite), is scheduled to launch in July 2011. The radar altimeter is an important remote sensing instrument carried on the HY-2 satellite. This study is supported by the"construction of HY-2 ground application system"and is focused on the waveform reconstruction calculation method development based on the data from HY-2 radar altimeter. Results will be applied to the processing of waveform data from HY-2 radar altimeter.The main works in this study are as following:1,Determined the data processing and classification method of HY-2 satellite radar altimeter based on analyzing current foreign satellite radar altimeter data processing and classification. HY-2 satellite radar altimeter data are divided into level 0, level 1 and level 2. Data processing method and flowchart of level 1B and level 2 are introduced.2,Several commonly used radar altimeter waveform reconstruction methods are put forward in this study. Discussed the reconstruction of HY-2 radar altimeter waveform based on the above study. Since HY-2 satellite has not been launched, data of HY-2 airborne altimeter waveform are used instead. In this study we focused on the main steps involved in HY-2 radar altimeter waveform reconstruction including thermal noise elimination, normalization, starting point of rising edge calculation, half power point calculation, tracking errors compensation and etc. Significant wave height was also retrieved in this study.3,The synchronized GPS data are used to confirm the observation height which is calculated by reconstructed altimeter waveform data. Results showed that the observation height of the two groups had the same variation trend. When comparing the SWH calculated by reconstructed radar altimeter waveform data with spot buoy data and Jason-1 satellite data, the RMS was found to be less than 50cm.The main results in this study are as following:The two comparisons above indicate the HY-2 radar altimeter waveform reconstruction method discussed in this thesis fits the HY-2 radar altimeter and can give good results on observation height and SWH.