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首页> 美国卫生研究院文献>Proceedings of the National Academy of Sciences of the United States of America >Lake sediments record large-scale shifts in moisture regimes across the northern prairies of North America during the past two millennia
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Lake sediments record large-scale shifts in moisture regimes across the northern prairies of North America during the past two millennia

机译：在过去的两千年中整个北美北部大草原的湖泊沉积物都记录了水分状况的大规模变化

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摘要

Six high-resolution climatic reconstructions, based on diatom analyses from lake sediment cores from the northern prairies of North America, show that shifts in drought conditions on decadal through multicentennial scales have prevailed in this region for at least the last two millennia. The predominant broad-scale pattern seen at all sites is a major shift in moisture regimes from wet to dry, or vice versa (depending on location), that occurred after a period of relative stability. These large-scale shifts at the different sites exhibit spatial coherence at regional scales. The three Canadian sites record this abrupt shift between anno Domini 500 and 800, and subsequently conditions become increasingly variable. All three U.S. sites underwent a pronounced change, but the timing of this change is between anno Domini 1000 and 1300, thus later than in all of the Canadian sites. The mechanisms behind these patterns are poorly understood, but they are likely related to changes in the shape and location of the jet stream and associated storm tracks. If the patterns seen at these sites are representative of the region, this observed pattern can have huge implications for future water availability in this region.
机译：根据对来自北美北部大草原的湖泊沉积物核心的硅藻分析，进行了六次高分辨率气候重建，结果表明，至少在过去的两千年中，该地区普遍经历了数十年至数百年尺度的干旱状况变化。在所有站点上看到的主要的大规模模式是湿度状态从湿到干的主要变化，反之亦然（取决于位置），这是在相对稳定的一段时间后发生的。这些不同地点的大规模变化在区域尺度上表现出空间连贯性。加拿大的三个站点记录了在多米尼500和800之间的突然转变，随后情况变得越来越多。美国的所有三个站点都发生了明显的变化，但是这种变化的时间是在多米尼（Domini）1000和1300之间，因此要晚于所有加拿大站点。对这些模式背后的机理了解甚少，但它们可能与射流的形状和位置以及相关风暴路径的变化有关。如果在这些地点看到的模式代表了该地区，那么这种观察到的模式将对该地区未来的水供应产生巨大影响。

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