Warm and cold wet states in the western United States during the Pliocene–Pleistocene
Warm and cold wet states in the western United States during the Pliocene–Pleistocene
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上新世-更新世期间美国西部的温暖和寒冷湿润状态
DOI：
10.1130/g39962.1
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发表时间：
2018
期刊：
影响因子：
5.8
通讯作者：
C. P. Chamberlain
中科院分区：
文献类型：
--
作者：
Daniel E. Ibarra;Jessica L. Oster;M. Winnick;Jeremy K. Caves Rugenstein;Michael P. Byrne;C. P. Chamberlain
湖泊的大小分布记录了降水输送与蒸发之间的竞争。在比工业化前更冷的最新更新世冰川期（约 14-29ka）和比工业化前更温暖的上新世中期（约 2.9-3.3 Ma），美国西部的最终排水盆地湖泊丰富。为了了解允许形成湖泊的水文气候条件，我们将湖泊质量平衡方程与水和能量平衡框架 (sensuBudyko) 结合起来。此外，我们使用末次盛冰期（LGM，19-26ka）和上新世中期的气候模型模拟，将古湖泊面积分布与正演模拟的湖泊面积进行了比较。我们得出的结论是，上新世-更新世比现代更温暖和更冷的时期通过类似的机制导致了美国西部最终排水盆地比现代更湿润的条件。具体来说，末次盛冰期期间湖泊的存在反映了降水量的增加以及蒸发需求的减少。在大盆地南部，LGM 湖泊需要大幅增加整个地区的降水量。在上新世中期，蒸发需求增加，需要增加降水来维持湖泊。此外，降水的增加和上新世中期湖泊沉积物主要分布在西南地区，与所提出的改变这一时期区域水文气候的平均“类厄尔尼诺”条件一致。这些观察结果表明，在间冰期，美国西部处于当地干旱最大值范围内，全球气温的长期升高和降低都与过去美国西部大部分地区的湿润条件有关。
The size distribution of lakes records the competition between precipitation delivery and evaporation. Lakes were abundant in the terminally draining basins of the western United States (USA) during both the colder-than-preindustrial latest Pleistocene glacial period (ca. 14–29 ka) and the warmer-than-preindustrial mid-Pliocene (ca. 2.9–3.3 Ma). To understand the hydroclimatic conditions that permitted lakes, we couple lake mass balance equations with a water and energy balance framework (sensuBudyko). Further, we compare paleo-lake area distributions to forward-modeled lake areas using climate model simulations of the Last Glacial Maximum (LGM, 19–26 ka) and mid-Pliocene. We conclude that both warmer- and colder-than-modern periods of the Pliocene–Pleistocene resulted in wetter-than-modern conditions in the terminally draining basins of the western USA through similar mechanisms. Specifically, the presence of lakes during the LGM reflects increased precipitation in addition to decreased evaporative demand. In the southern Great Basin, LGM lakes require large increases in precipitation across the region. During the mid-Pliocene, increased evaporative demand necessitated increased precipitation to maintain lakes. Further, the increase in precipitation and dominantly southwestern distribution of mid-Pliocene lake deposits is consistent with proposed mean “El Niño–like” conditions altering regional hydroclimate during this period. These observations suggest that during interglacial periods, the western USA resides within a local aridity maximum, and both long-term increases and decreases in global temperatures have been associated with wetter conditions across much of the western USA in the past.