Hydroclimate Dipole Drives Multi‐Centennial Variability in the Western Tropical North Atlantic Margin During the Middle and Late Holocene
Hydroclimate Dipole Drives Multi‐Centennial Variability in the Western Tropical North Atlantic Margin During the Middle and Late Holocene
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DOI：
10.1029/2020pa004184
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发表时间：
2021-07
影响因子：
3.5
通讯作者：
R. Sullivan;Peter J. van Hengstum-Peter-J.-van Hengstum-2130088925;S. Coats;J. Donnelly;A. Tamalavage;T. S. Winkler;N. Albury
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文献类型：
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作者：
R. Sullivan;Peter J. van Hengstum-Peter-J.-van Hengstum-2130088925;S. Coats;J. Donnelly;A. Tamalavage;T. S. Winkler;N. Albury
北大西洋副热带高压（NASH）西部边缘的经向移动产生了一个驱动美国东南部和加勒比地区水文气候变化的偶极子。西南部的流离失所抑制了加勒比海南部的降雨。西北部的位移导致美国东南部和北方加勒比海地区干旱。对21世纪世纪的预测表明，NASH将在更大范围内流离失所，这将危及依赖雨水灌溉含水层的加勒比岛屿社区。虽然最近的工作表明，大西洋和太平洋-大气的变化影响了NASH在仪器期间，很少有人知道NASH的行为和随后的水文气候响应在较长的时间尺度。为了解决这一限制，我们开发了一个6000年的降雨记录，通过分析方解石筏沉积物存档在沉积物中从沿海天坑在巴哈马东北部（阿巴科岛）。增加（减少）方解石筏沉积提供了证据，增加（减少）降雨驱动NASH的变化。我们使用社区地球系统模型的模拟来支持这种解释。这些模拟提高了我们对NASH行为在与重建一致的时间尺度上的理解，并表明了太平洋状态的重要作用。此外，模型模拟和区域水文气候重建汇编显示，NASH驱动的偶极子主导了加勒比海北方和南部的百年时间尺度降雨。这些结果使全新世加勒比水文气候变率成为焦点，同时为区域气候的现在和未来变化提供了重要的背景。此外，这项研究强调需要改进对太平洋状况的未来预测，以便为面临风险的加勒比社区提供最佳的水资源短缺缓解战略。
Meridional shifts of the North Atlantic Subtropical High (NASH) western edge create a dipole that drives hydroclimate variability in the southeastern United States and Caribbean region. Southwest displacements suppress rainfall in the southern Caribbean. Northwest displacements drive southeast United States and northern Caribbean drying. Projections for the 21st century suggest a more meridionally displaced NASH, which jeopardizes Caribbean island communities dependent on rain‐fed aquifers. While recent work indicates that Atlantic and Pacific Ocean‐atmosphere variability influenced the NASH during the instrumental period, little is known about NASH behavior and subsequent hydroclimate responses over longer timescales. To address this limitation, we developed a ∼6000‐years long rainfall record through the analysis of calcite raft deposits archived within sediments from a coastal sinkhole in the northeast Bahamas (Abaco Island). Increased (decreased) calcite raft deposition provides evidence for increased (decreased) rainfall driven by NASH variability. We use simulations from the Community Earth System Model to support this interpretation. These simulations improve our understanding of NASH behavior on timescales congruous with the reconstruction and suggest an important role for the state of the Pacific Ocean. Furthermore, model simulations and a compilation of regional hydroclimate reconstructions reveal that the NASH‐driven dipole dominates northern and southern Caribbean rainfall on centennial timescales. These results bring Holocene Caribbean hydroclimate variability into sharper focus while providing important context for present and future changes to regional climate. Additionally, this study highlights the need for improved future predictions of the state of the Pacific Ocean to best inform water scarcity mitigation strategies for at‐risk Caribbean communities.