Coral-based reconstruction of salinity and temperature variability in the southern Makassar Strait and its Influence on the Indonesian Throughflow

基于珊瑚的望加锡海峡南部盐度和温度变化重建及其对印度尼西亚通流的影响

• 批准号: 1030096
• 负责人: Braddock Linsley
• 金额: $ 33.99万
• 依托单位: SUNY at Albany
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-10-01 至 2012-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1030096&HistoricalAwards=false
• 关键词: Coral; based; reconstruction; salinity; temperature

The Indonesian Throughflow (ITF) is the main conduit for transporting surface and upper thermocline water from the western equatorial Pacific into the Indian Ocean. The volume and temperature of the ITF varies seasonally due to the seasonal influx of low salinity surface water from the South China and Java Seas into the Makassar Strait during the northern winter monsoon. This low salinity "plug" generates a northward pressure gradient in the Makassar Strait that seasonally inhibits the flow of warm surface water in the far western Pacific Ocean from freely flowing southward into the Indian Ocean. The net result is a cooling and freshening of the Indian Ocean thermocline. Despite the oceanographic significance of this seasonal freshening of the Makassar Strait on the ITF, little is known about century to decadal-scale variability of salinity in the Makassar Strait. Previous low-resolution studies based on sediment cores in the Makassar Strait indicate that during the Little Ice Age (~1600-1850 AD), salinity and sea surface temperature in the strait were both reduced. This research utilizes Porites sp. coral cores from Kapoposang in the southern Makassar Strait near S.W. Sulawesi and from Gili Meno in the Lombok Strait near Bali to develop partially replicated, near-monthly resolution, trace element (Sr/Ca) and stable isotope (d18Osw) records spanning the last 250 years. Results show that coral Sr/Ca variability accurately tracks the annual bi-modal sea surface temperature cycle. The research will enhance understanding of salinity and SST variability in this critical strait in order to constrain ITF variability over the last 250 years. Changes in the freshwater budget of the southern Makassar Strait are expected to alter the intensity of the "freshwater plug", with lower salinity in the Makassar Strait surface layer leading to a cooler ITF. Funding supports a postdoctoral associate and research experiences for undergraduates.

印度尼西亚贯穿流(ITF)是从赤道西太平洋向印度洋输送表层和上层温跃层水的主要渠道。由于北部冬季季风期间，来自南中国和爪哇海的低盐度地表水季节性地进入马卡萨尔海峡，因此ITF的体积和温度具有季节性变化。这种低盐度的“塞子”在马卡萨尔海峡产生了向北的压力梯度，季节性地阻止了遥远的西太平洋温暖的表层水自由地向南流入印度洋。最终的结果是印度洋温跃层的降温和清新。尽管Makassar海峡的这种季节性淡化对ITF具有海洋学意义，但对Makassar海峡盐度的世纪至十年尺度变化知之甚少。以往基于马卡萨尔海峡沉积物岩心的低分辨率研究表明，在小冰期(公元1600-1850年)，该海峡的盐度和海温都有所下降。本研究利用Porites sp.来自苏拉威西西南马卡萨尔海峡南部的卡波桑和巴厘岛附近龙目岛海峡的吉利·梅诺的珊瑚岩心形成了跨越过去250年的部分复制的近月分辨率、痕量元素(锶/钙)和稳定同位素(D18Osw)记录。结果表明，珊瑚的锶/钙变率较好地反映了年双峰海温周期。这项研究将加强对这一关键海峡的盐度和SST变异性的了解，以便限制过去250年来ITF的变异性。马卡萨尔海峡南部淡水收支的变化预计将改变“淡水塞子”的强度，马卡萨尔海峡表层盐度较低导致ITF较凉爽。资金支持博士后助理和本科生的研究经验。