| Summary: | 碩士 === 國立成功大學 === 水利及海洋工程學系碩博士班 === 94 === Surface current information is possible to be extracted from the X-Band radar backscatter. The value of representative water depth (RWD) is one of the most important factors in the image process to derive surface current from radar images. It cannot be ignored for the case of that the image is from shallow water area. The purpose of this paper is to study the estimation of RWD in order to find the correct sea surface current.
In addition to the field experiment, an image simulation method is developed to simulate images for further studies from various conditions of water depths, waves and currents. The RWD is tested from the water depth ranges that the image covers. The optimal RWD is then determined by the criteria on minima bias of input and analyzed currents. The result shows that the optimal RWD value has correlation with bathymetry slope. By regression analysis, the coefficient of correlation is 97%. An empirical formula is therefore derived to estimate the RWD.
In order to validity the result from image simulation, a field experiment is arranged. Sea surface current measured from GPS buoy is used for validation of present formula. It is shown that the result of sea surface current derived from radar images is improved by inputting the RWD estimated from the empirical formula in this study. The improvement is significant at the coastal area with small relative water depth.
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