| dc.description.abstract | Satellite altimetry Jason-2 has been used to observe global ocean surface topography with accuracy approximately up to 2.5 cm on the offshore. However, the accuracy will be significantly reduced over coastal waters due to the signal received by satellite was interfered by reflected signal from the land. Distruption to the received signal by the satellite will affect the waveform shape becomes more complex and more difficult to be analyzed. The waveform formed on the offshore, is the ideal waveform shape so called ocean waveform or Brown waveform. Calculation of the range between the satellite and earth's surfaces using ocean retracking method is not accurate if the analyzed waveform shape is not ideal. Therefore, it is necessary to do retracking using other methods. The purpose of this research was to compare the ability of several retracking methods and ocean retracking methods to produce better value of sea surface height (SSH) on coastal waters. This study used data from the SGDR-D (Sensor Geophysical Data Record type D) satellite Jason-2 (pass 242, 051, and 064 during the period of 2010 - 2012 at southern coastal of Central Java and West Java) and global geoid data EGM08 (Earth Gravitational Model 2008). In this research, compared the analysis perfomances of several retracking methods, such as the OCOG (Offset Centre of Gravity), ice, threshold, and improved threshold and the result from analysis of ocean retracking method. Analytical performances of the used methods were measured by calculating the improvement percentage (IMP) results. Results of this research indicated waveforms from coastal waters has a complex and peaky shape, in contrast to the condition of the waveforms on the offshore with the ideal shape. In general, ice retracking method was the most optimal method for analyzing waveforms on each pass. That method was able to produce sea surface height value from offshore to coastal waters with high accuracy. The trend of sea level change that occurred during 2010 - 2012 at the observation point in each pass used optimal retracking method indicated a declining pattern. Sea level change at the observation point on the pass 242, 051, and 064 were -18.17, -47.23, and -39.97 mm/year inrespectively. | en |
