王冑2006-07-252018-06-282006-07-252018-06-282004http://ntur.lib.ntu.edu.tw//handle/246246/14841雷達是近代一種重要的遙測工具，雷達發射出的電磁波在接觸到海面粗糙構造後會發 生後向散射，其強度與海面粗糙物之分佈性質有關，因此可以根據雷達回波訊號強度來反 算一些會影響到海面粗糙物之分佈性質的外在物理因子(如波浪、風力、雨滴、水流分佈等 等)的特性。在河口海域，河川流出之沖淡水與外海高鹽份海水相遇時會形成明顯的舌狀構 迼，沖淡水舌之外緣為水流輻合帶(鋒面)，在輻合帶中海面小波受到波流交互作用其能量 密度將會增大，因此我們可預期沿著水舌外緣將會形成一道海面粗糙度較高的區域，是以 從雷達回波上便能夠界定出沖淡水舌的位置所在。本年度我們在淡水沙崙港邊裝設了岸置 雷達以監看淡水河沖淡水舌之變化情形，資料顯示在開始退潮時，呈舌狀構造的強輻合區 會先在沙崙港外形成，隨後此舌狀構造範圍逐漸擴大，並向著西南方之台北港外堤方向擴 展，但其強度則漸減弱，然後慢慢消失。淡水河流量大時，舌狀區向外海擴張較遠，反之 則比較侷限於河口近岸，這些趨勢和水文觀測資料相合。Radar is an important tool for remote sensing. The strength of back-scattering, generated by Radar waves hitting sea surface roughness elements, i.e. small waves, is associated closely with the distribution of surface roughness elements and with the strength of the latter as well. Therefore, external parameters, such as waves, winds, raindrops and flow structures, etc. whose properties can excite small waves thus could be deduced inversely from the back-scattering signals of Radar. A tongue-like river plume is a typical pattern usually observed at an estuarine region where the brackish effluents from the river meet the offshore saltier waters. The outer rim of a river plume is a convergence zone, where small waves become energetic causing by the wave-current interaction mechanism. Therefore, we anticipate that the outer rim of a river plume is a zone with high sea surface roughness, which could be detected from the Radar imageries readily. This year, we have set up a land-based Radar station at Sar-Luen, Tanshui. We expect to get more insights on the response of Radar imageries to the behavior of flow fields, and we may extend and utilize these understandings to study the internal solitons in the South China Sea area, by virtue of these measurements. Field observations at Sar-Luen do show significant patterns of the movement of the tongue-like river plume which is associated with the semi-diurnal tidal cycle closely. The plume pattern shown by Radar measurements is consistent with the field CTD surveys well.application/pdf120615 bytesapplication/pdfzh-TW國立臺灣大學海洋研究所reporthttp://ntur.lib.ntu.edu.tw/bitstream/246246/14841/1/922611M002005.pdf