Observation of the deep Indonesian throughflow using helium isotopes
Observation of the deep Indonesian throughflow using helium isotopes
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DOI：
10.1007/s10872-020-00560-8
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发表时间：
2020-08
影响因子：
2.3
通讯作者：
M. Escobar;N. Takahata;H. Obata;Y. Sano
中科院分区：
文献类型：
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作者：
M. Escobar;N. Takahata;H. Obata;Y. Sano
海洋中的氦同位素是热液输入和深海环流非常有用的示踪剂。与不稳定的微量元素不同，惰性气体是惰性的，不与水柱中的其他物质发生反应。先前对印度洋的研究表明，该地区的氦同位素主要通过流经印度尼西亚群岛的洋流从印度中部的洋中脊、辐合边界和太平洋释放出来。这些印尼水域然后作为印尼通流（ITF）通过浅海进入印度洋。ITF在全球气候中扮演着重要的角色，因为它是太平洋和印度洋之间温跃层水的主要通道。我们展示了2018年12月在东印度洋进行的国际印度洋考察（IIOE-2）的新氦同位素数据。氦同位素是用东京大学大气与海洋研究所的惰性气体质谱仪测量的。我们将我们的数据与以前的考察数据进行了比较，并讨论了爪哇附近氦同位素的来源和分布。在1000米处观察到ITF的高he值。双组分混合模型的应用使我们能够估算出在观测区域内的ITF分数，并澄清了ITF在深层的流动。此外，从萨武海向印度洋的深层ITF流量估计为~ 0.8 ~ 1.6 Sv。根据爪哇岛海岸附近的台站，在3000米的地方可能有一个深流或热液源，沿着爪哇岛向南输送富含3he的水。
Helium isotopes in the ocean are very useful tracers of hydrothermal input and deep-sea circulation. Unlike labile trace elements, noble gases are inert and do not react with other substances in the water column. Previous studies in the Indian Ocean showed that helium isotopes in the region were discharged mainly from the central Indian midocean ridge, convergent boundaries, and the Pacific Ocean via currents that flow through the Indonesian archipelago. These Indonesian waters then exit out as the Indonesian Throughflow (ITF) into the Indian Ocean through shallow sills. The ITF plays a significant role in global climate, because it serves as the main pathway of thermocline waters between the Pacific Ocean and Indian Ocean. We present new helium isotope data from International Indian Ocean Expedition (IIOE-2) at the east Indian Ocean in December 2018. Helium isotopes were measured using a Noble Gas Mass Spectrometer at the Atmosphere and Ocean Research Institute, The University of Tokyo. We compare our data with those from previous expeditions and discuss the source and distribution of helium isotopes near Java. Waters with high excess3He from the ITF were observed at 1000 m. Application of two-components mixing model enabled us to estimate ITF fraction in the observed area and to clarify the ITF flow in the deep layer. Moreover, flow rate of the deep ITF from Savu sill to Indian Ocean was estimated to be ~ 0.8–1.6 Sv. Based on stations near the Java coast, there could be a deep current or hydrothermal source at 3000 m that advects water enriched in3He southwards along the Java Island.