Precise mass and volume determination of the silicon sinker for sea water densimetry
Precise mass and volume determination of the silicon sinker for sea water densimetry
复制标题
用于海水密度测定的硅沉子的精确质量和体积测定
DOI：
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
Y. Fujita
中科院分区：
文献类型：
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作者：
Y. Kayukawa;Y. Fujita
海水热力学方程2010（TEOS-10）中的绝对盐度关系式被广泛应用于全球海洋环流的计算，需要精确测量海水的密度以修正该关系式。在NMIJ，开发了一种用于海水密度测量的流体静力称重装置，以提供相对不确定度为1 ppm的海水密度标准物质。为此，一个100克的硅单晶沉降片新开发的浮力测量。沉降片体积的测定不确定度应优于1 ppm。NMIJ提供的PFM（浮选压力法）是测定沉降片密度的有效方法，其不确定度约为0.1ppm。然而，对于质量校准，在与100 g OIML重量的常规质量比较中的不确定性大于0.05 mg，其对应于测量的海水密度的1.2 ppm。因此，在本研究中，质量测量的基础上，分多程序。即，准备一组由硅单晶制成的500 g、200 g、200 g、100 g的盘砝码。其质量通过使用1 kg硅球（NMIJ-S5）的多次测量进行校准，质量（17 μg）和体积（0.15 ppm）的不确定度极小。介绍了硅盘砝码的设计、分多次校准的过程以及由此确定的沉降片质量/体积。
Accurate density measurement for seawater is demanded to revise the absolute salinity correlation used in the Thermodynamic Equation of Seawater 2010 (TEOS-10), which is widely used to calcurate the global ocean circulation. In NMIJ, a hydrostatic weighing apparatus for sea water densimetry was developed to provide CRM for sea-water density with relative uncertainty of 1 ppm. For this purpose, a 100 g silicon single-crystal sinker was newly developed for buoyancy force measurements. The volume of the sinker should be determined with better uncertainty than 1 ppm. PFM (pressure of floatation method) provided in NMIJ is effective way to determine the sinker density with about 0.1 ppm uncertainty. For mass calibration, however, uncertainty in the conventional mass comparison with 100 g OIML weight is larger than 0.05 mg which corresponds to 1.2 ppm of sea water density measured. In the present study, therefore, mass measurement based on sub-multiple procedure. Namely, a set of 500 g, 200 g, 200 g, 100 g disc weight made of silicon single crystal was prepared. Their masses were calibrated by sub-multiple measurement with 1 kg silicon sphere (NMIJ-S5) having extremely small uncertainty of mass (17 μg) and volume (0.15 ppm). Design of the silicon disc weights, procedure of the sub-multiple calibration, and thus determined sinker mass/volume are presented.