Last Millennium Meridional Shifts in Hydroclimate in the Central Tropical Pacific
Last Millennium Meridional Shifts in Hydroclimate in the Central Tropical Pacific
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DOI：
10.1002/2017pa003233
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发表时间：
2018-04
影响因子：
3.5
通讯作者：
M. Higley;J. Conroy;Susan Schmitt
中科院分区：
文献类型：
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作者：
M. Higley;J. Conroy;Susan Schmitt
重建过去的热带太平洋水文气候的空间结构的变化，需要过去的水分平衡跨越降水的空间梯度的档案。到目前为止，只有一个600年，陆地记录的水文气候是从华盛顿湖，华盛顿岛的热带太平洋中部（CTP），限制了能力，以检验假设的位置CTP热带辐合带（ITCZ）在过去的一千年。华盛顿岛以南3°基里巴斯共和国基里巴斯蒂马蒂30号湖的新湖泊沉积物记录为过去CTP ITCZ位置提供了额外的限制。湖30地球化学和沉积学数据表明，从公元900年至1200年，增加微生物席的发展和石膏沉淀的插曲，与中世纪气候异常（MCA）。我们推断干燥的条件下，在MCA在Kiritimati的华盛顿湖代理记录表明潮湿的条件下，这表明CTP ITCZ被移位向北在MCA相对于其今天的位置。在MCA和小冰期（LIA）之间的过渡，湖30沉积物成为主要的碳酸盐，这表明过渡到潮湿的条件和ITCZ相对于其MCA位置的南移。然而，热带太平洋水文气候敏感性代用记录的合成并没有指出MCA和LIA的一致的空间或时间变化模式，这表明在过去的一千年中，百年尺度的热带太平洋水文气候受到多重影响。
Reconstructing past changes in the spatial structure of tropical Pacific hydroclimate requires archives of past moisture balance across spatial gradients of precipitation. To date, only one, 600‐year, terrestrial record of hydroclimate is available for the central tropical Pacific (CTP) from Washington Lake, Washington Island, limiting the ability to test the hypotheses regarding the location of the CTP Intertropical Convergence Zone (ITCZ) in the last millennium. A new lake sediment record from Lake 30, Kiritimati, Republic of Kiribati, 3° south of Washington Island, provides additional constraints on past CTP ITCZ position. Lake 30 geochemical and sedimentological data indicate an episode of increased microbial mat development and gypsum precipitation from 900 to 1200 CE, coincident with the Medieval Climate Anomaly (MCA). We infer drier conditions during the MCA at Kiritimati as the Washington Lake proxy record indicates wetter conditions, suggesting that the CTP ITCZ was displaced northward during the MCA relative to its position today. At the transition between the MCA and the Little Ice Age (LIA), Lake 30 sediment becomes predominantly carbonate, suggesting a transition to wetter conditions and a southward shift of the ITCZ relative to its MCA position. However, a tropical Pacific synthesis of hydroclimate‐sensitive proxy records does not point to a consistent spatial or temporal pattern of variability in the MCA and LIA, suggesting multiple influences on centennial‐scale tropical Pacific hydroclimate during the last millennium.