潮位觀測技術

On the Tide Observation Teehniques

鄰近太陽與月球，地球的表面因星體重力發生週期性的空間變化。地球表面的71%為水體覆蓋，水體受到日月影響產生潮汐，其幅度較陸地為高，成為自然環境中一項顯著的現象。海潮觀察與探討，是人類應用海洋、湖泊、與河流資源，以及了解自然的重要項目。潮位觀測使用之技術，包含水尺、浮筒、壓力、音波、雷達、雷射等等，除了上述量測單一維度、定點安置型的固定潮位觀測設施外，近代也應用衛星觀測，包含GNSS浮標、GNSS-R、與衛星雷達測高，這些方法除了以橢球體為參考基準的水面高度外，亦同時獲得水平位置。而且，其中浮標與雷達測高實質上並非定點設置，更豐富化潮位觀測方式。各種技術分別有其限制與優點，本文之目的在於回顧常用的潮位計種類與原理，並探討其特性。
Due to the proximity of Earth with the sun and moon, gravitational forces create periodic changes on the surface of the planet. More than 70% of the Earth is covered with water. In these area, the magnitude of changes is more significant than that of the land. The tide is a phenomenal event on Earth, with sea tide observation contributing greatly to the use of waterbodies such as sea, river, and lakes, as well as human understanding of nature. The technology applied for tide measurement, includes tide staff, float, pressure, acoustic, RADAR, laser, and others. Besides those solely measuring height, and installed on a fixed site, there are techniques based on satellite, such as GNSS buoy, GNSS-R, and satellite RADAR altimeter, developed in contemporary times. Classified as part of ''height modernization'', besides the sea surface height based on ellipsoid, these techniques provide horizontal position simultaneously. Buoy and RADAR altimeters are not installed at fixed sites, and serve to enrich the tide observation methods. Each technology has its advantages and limitations. This paper intends to briefly review the commonly applied methodologies for tide measurement, including their principle and characteristics.