Origin and Hemispheric Linkage of Millennial-Scale Climate Variability in the Pacific

该奖项将评估各种机制，这些机制被认为是造成过去约65,000年来太平洋东部边缘高沉积速率岩心表层和浅层地下水团千禧年尺度变化的原因。在东北太平洋、赤道太平洋和东南太平洋选择了三个关键区域进行详细研究，因为它们提供了一个机会来检验三个假设，这些假设可能影响从大气-海洋耦合模式研究得出的气候变率模式。第一个假设假设海表温度异常通过大气从北大西洋迅速传递到北太平洋。这意味着北太平洋有强烈的响应，而南方几乎没有响应。第二个假设假设全球温度异常随着温盐环流的变化而缓慢传播，并预测东南太平洋中间水温和通风的巨大变化，这些变化相对于北半球的变化是相移的。第三个假设假设快速气候振荡起源于热带太平洋，通过厄尔尼诺-南方涛动(ENSO)类型的机制，并伴随着对海洋和大气的影响。这意味着东热带太平洋的海面温度(SST)和跃层结构发生了重大变化，能量沿东缘向两半球传输。研究人员预计，基于对采样点的仔细选择和高分辨率古气候指标的应用，将建立东太平洋千禧年尺度变化的空间“指纹”。这一点很重要，因为它将有助于解决造成该区域千年尺度变化的主要机制，特别是半球之间的联系以及热带和温带气候变异性之间的相互作用。

This award will assess various mechanisms thought to be responsible for millennial-scale variability in surface and shallow subsurface water masses in high-sedimentation rate cores from the eastern margin of the Pacific over the past ~65,000 years. Three key regions were chosen for detailed study in the Northeast Pacific, Equatorial Pacific, and Southeast Pacific, because they offer an opportunity to test three hypotheses that might affect patterns of climate variability derived from coupled atmosphere-ocean model studies.The first hypothesis assumes that sea-surface temperature anomalies are transmitted rapidly from the North Atlantic to the North Pacific via the atmosphere. This implies a strong response in the North Pacific and little or no response in the south.The second hypothesis assumes that global temperature anomalies propagate slowly in response to changes in thermohaline circulation and predicts large changes in intermediate water temperatures and ventilation in the Southeast Pacific that are shifted in phase relative to changes in the northern hemisphere.The third hypothesis assumes that rapid climate oscillations originate in the tropical Pacific via El Nino-Southern Oscillation (ENSO) type mechanisms with attendant effects on the ocean and atmosphere. This implies major changes in sea-surface temperatures (SST) and pycnocline structure in the eastern tropical Pacific and transmission of energy poleward into both hemispheres along the eastern margin. The researchers expect, based on a careful selection of sampling sites and the application of high-resolution paleoclimatic proxies, to establish the spatial "fingerprint" of millennial-scale variability in the Eastern Pacific. This is important because it will help resolve the primary mechanisms responsible for millennial-scale changes in the region especially the linkage between the hemispheres and the interaction between tropical and extratropical climate variability.