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

- 主要目标是确定太平洋表层三个区域化石燃料二氧化碳的相对数量，并了解过去两个世纪在这些地点发生的环流变化的性质。要研究的三个区域是：标准太平洋（夏威夷群岛，北纬20度，西经156度）、赤道西太平洋（瑙鲁岛，南纬1度，东经167度）和赤道东太平洋（加拉帕戈斯群岛，南纬1度，西经91度）。本研究所用的方法是用加速器质谱（AMS）技术测量高精度的A ~ 4C和一年生带状珊瑚骨骼的稳定同位素（If O和S ~（13）C）。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，另一个主要目标是将过去世纪北大西洋表层环流和环流的年际变化与全新世早期的年际变化进行比较。高精度'4C在南佛罗里达的古代珊瑚礁珊瑚将使我们能够确定是否发生在高温（4200 yBP），在一个非常大的胫骨在大气'4C（2700 yBP）和中世纪之前的时期（1300 yBP）的通风大脉冲。这些研究将增加关于海洋、表层或深层在人类时间尺度上的变化性质的知识。14 C数据为海洋环流模型和海洋在过去气候变化中的作用理论提供了关键测试。PI将进行模拟练习，以揭示太平洋和大西洋热带和亚热带地区近地面环流的非稳态变化。

-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.