由海水壓力化算海水深度討論

On the Depth Derivation from Seawater Pressure

海水壓力與其度相關，藉由感測海水壓力，可以量測水深。對應關係約為1decibar壓力，1m水深。一般通用之化算公式，包含淡水公式、簡易水深公式、以及UNESCO（1983）公式。UNESCO（1983）公式並非最嚴謹之物理數學模型，但是為實務上十分接近嚴謹模型者，由聯合國組織UNESCO推薦。UNESCO（1983）公式中包含海水比容值與比容異常兩個部分，均需除以正常重力，以化算為深度。本研究以實務作業的考量，分析UNESCO（1983）公式中之計算細節，並討論簡易水深公式與UNESCO（1983）公式之差異。
Seawater pressure is linearly related to seawater depth. From the measurement of pressure, the depth could be derived. The approximate relationship is about one decibar to one meter. Commonly applied conversion equations include the freshwater equation, simplified depth equation, and UNESCO (1983) equation. UNESCO (1983) is not the most rigorous mathematical model for marine physics, but practically very close to the rigorous model. This conversion equation is endorsed by UNESCO, an organization affiliated with United Nations. The UNESCO (1983) equation contains specific volume and specific volume anomaly. Both parts need to be divided by normal gravity at each site for conversion. This study reviews the UNESCO (1983) equation and compares it with the simplified depth equation.