Indentification of Non-Steady State Changes in Surface OceanCirculation from Radiocarbon in Corals

-主要目标是确定太平洋表面三个地区化石燃料二氧化碳的相对含量，并了解过去两个世纪在这些地区发生的环流变化的性质。要研究的三个地区是北太平洋（夏威夷群岛，20ÝN, 156ÝW）、西赤道太平洋（瑙鲁岛，1ÝS, 167ÝE）和东赤道太平洋（加拉帕戈斯群岛，1ÝS, 91ÝW）。本研究中使用的方法是使用AMS（加速器质谱）技术和稳定同位素（如果O和sl3C）测量年带状珊瑚骨骼的高精度A'4C。为了将这些结果与几千年前可能发生的环流变化联系起来，另一个主要目标是比较过去一个世纪北大西洋地表环流和环流的年际变化（Druffel， 1997年出版）与全新世早期存在的年际变化。对来自南佛罗里达的古珊瑚礁珊瑚进行高精度的温度测量，将使我们能够确定大的通风脉冲是否发生在低温期（4200 yBP）结束时，在一个非常大的大气温度波动（2700 yBP）期间，以及在中世纪时期（1300 yBP）之前。这些研究将在人类的时间尺度上增加关于海洋、表层或深层变化性质的知识。14C数据为海洋环流模型和海洋在过去气候变化中作用的理论提供了关键的检验。PI将进行模拟演习，以揭示太平洋和大西洋热带和亚热带地区近地表环流的非稳态变化。

-Major objectives are to establish the relative amounts of fossil fuel CO2 in three regions of the surface Pacific, and to understand the nature of circulation changes that have occurred at these sites over the past two centuries. The three regions to be studied are the Norm Pacific (Hawaiian Islands, 20ÝN, 156ÝW), western equatorial Pacific (Nauru Island, 1ÝS, 167ÝE), and the eastern equatorial Pacific (Galapagos Islands, 1ÝS, 91ÝW). The methods used in this study are the measure of high grecision A'4C using AMS (accelerator mass spectrometry) techniques and stable isotopes (if O and sl3C) of annually banded coral skeletons. To link these results with circulation changes that may have taken place several thousands of years ago, another major objective is to compare interannual variability in surface mLxing and circulation in the North Atlantic during the past century (Druffel, 1997, in press) to that which existed earlier in the Holocene. High precision &'4C in ancient reef corals from South Florida will allow us to determine whether large pulses of ventilation took place at the end of the Hypsithermal (4200 yBP), during a very large shin in atmospheric &'4C (2700 yBP) and just before the Medieval Was Period (1300 yBP). These studies will add knowledge about the nature of variability in the ocean, surface or deep, on human time scales. 14C data provides critical tests for ocean circulation models and theories of the role of the ocean in past climate change. Modeling exercises will be performed by the PI to uncover non steady state changes in near surface circulation in the tropical and subtropical areas of the Pacific and Atlantic Oceans.