海水盐度计量进展:TEOS-10及绝对盐度

Development in Seawater Salinity Metrology:TEOS-10 and Absolute Salinity

新的海水热力学方程TEOS-10及绝对盐度,有效解决了EOS-80和PSS-78的缺陷。TEOS-10通过构建海水的Gibbs函数来计算海水的各种属性,尤其是熵、焓、化学势等热力学属性,应用扩展到淡水、海冰、水蒸气。输入TEOS-10的盐度自变量绝对盐度,系统地考虑了海水组分的空间差异和中性物质对海水密度的影响;它能更加真实和准确地描述海水的属性,并且可以直接溯源至SI。2009年以来,UNESCO/IOC等国际组织相继认可并推荐海洋学界采用TEOS-10,这将推动海洋科学的发展。然而,在实际应用中,绝对盐度仍无法完全取代实用盐度,存在诸如计算方法本身并不完善、在数据库中直接存储绝度盐度数据可能导致混乱等一些问题。最后,讨论了采用绝对盐度对海水盐度计量可能产生的影响。

The new thermodynamic equation of seawater, TEOS-10, as well as absolute salinity, can effectively make up the deficiencies of EOS-80 and PSS-78. Based on the founding of Gibbs function of seawater, TEOS-10 can calculate the properties of seawater, especially the thermodynamic properties such as entropy, enthalpy and chemical potential; it is also applicable to fresh water, sea ice and water vapor. The salinity variable input TEOS-IO is absolute salinity, which systematically accounts for the spatial variation of seawater composition across the world, as well as the influence of dissolved neutral species on the density of seawater. Absolute salinity can provide a real and more accurate description of seawater properties, and it is also consistent with SI. Since 2009, international organizations such as UNESCO/IOC have all endorsed TEOS-IO and recommended the use of it in the oceanography community, which will promote the development of oceanography. However, in practical applications, absolute salinity will not completely replace practical salinity owing to some reasons, for example, the algorithm used to determine absolute salinity is still immature, and currently it may cause confusion if salinity data is stored as absolute salinity in the database. Finally, the influence of absolute salinity on the seawater salinity metrology is discussed in this paper.