| Summary: | 碩士 === 國立成功大學 === 水利及海洋工程學系碩博士班 === 93 === The occurrence of wave breaking on the sea surface effects the flow fields significantly in the nearshore region, and it is believed to play an important role in the coastal engineering, ocean engineering, harbor engineering, and so on. However, the mechanisms for causing the waves to break on the ocean surface are complicated to derive and measure the location where waves break. As the science and technology progress, the techniques of remote sensing get more and more developed. The use of the pulsed Doppler microwave radar system becomes a possible way to detect where waves break on the nearshore sea surface.
In this paper, we use the pulsed Doppler microwave radar system to observe the nearshore waves nearby the Shuang-Si estuary at Fu-Long village, Gong-Liao township, Taipei county. Along the same measuring line, the character of subjective scatterers under the radar illuminated area changes and the features of radar backscatter will be different. The analysis of radar backscatter involved radar cross section, Doppler frequency shift, and Doppler bandwidth from the sea surface was accomplished. Eventually, the maximum radar cross section and Doppler frequency shift on the same measuring line, and connect the position on every measuring line respectively. The radar system was shown the capability to delineate the location of breaking wave clearly.
Compared with the traditional measurement, in aspect of time, the application of pulsed Doppler microwave radar system for nearshore wave observation can accomplish a detection case promptly within 20 minutes; furthermore, in aspect of space, it can scan as far as 2 kilometer that is sufficient for most nearshore events to achieve a measurement operation. Significantly, it is safe and secure for investigators and instruments that they can accomplish all detective operation successfully.
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