海水热力学方程TEOS-10及其与海水状态方程EOS-80的比较

新的2010年海水热力学方程TEOS-10采用1990年国际温标以及考虑世界大洋海水组成空间差异的绝对盐度,与旧的1980年海水状态方程EOS-80相比,具有更高的准确度和更广的适用范围,能够直接计算包括熵、焓、热容量在内的旧方程无法计算的热力学变量,将给海洋学研究带来重要的影响。借助气候态平均数据计算的结果表明,新旧方程计算的密度之差,在全球大多数海域可超过10-2kg/m3。在赤道以北的太平洋和印度洋海域,包括中国东海和南海的深海区域,该差别尤为显著,在精度要求较高的研究中必须予以考虑。新方程对密度计算的这一修正主要归因于其首次提出的绝对盐度,考虑了包括中性溶质在内的所有溶质的作用,弥补了实用盐标的缺陷。新旧方程计算冰点等其他物理量也有相应的修正。应尽快推广应用TEOS-10以及绝对盐度,充分发挥其对海洋学发展的推动作用。

The Thermodynamic Equation of Seawater 2010 and Its Comparison with the Equation of Seawater 1980

With the International Temperature Scale 1990 and the Absolute Salinity that accounts for the effects of the spatial variation of seawater composition around the world ocean, the new International Thermodynamic Equation of Seawater 2010 (TEOS-10) has higher accuracy and wider application scope, Compared to the Equation of Seawater 1980 (EOS-80). TEOS-10 allows the calculation of many thermodynamic quantities, such as entropy, enthalpy and heat content, that were not available from EOS-80. Therefore, TEOS-10 will make significant impacts on the development of oceanography. TEOS-10 is compared with EOS-80 based on their applications on climatological averaged data. The difference of the calculated density with these two equations reaches 10^-2 kg/m³ in most regions of the world ocean. It is particularly significant in the North Pacific Ocean, North Indian Ocean and also the deep areas in East China Sea and the South China Sea. So in these regions, this difference must be considered in the studies and applications that require high accuracy. The improvements of the new equation are mostly due to a new salinity variable, Absolute Salinity that considers the impacts of all the solutes in seawater, including the neutral solutes, which could make up the deficiency of the Practical Salinity. In order to promote the development of oceanography, the Absolute Salinity and TEOS-10 are recommended to be applied as soon as possible.