Atmospheric river changes shaped mid-latitude hydroclimate since the mid-Holocene
Atmospheric river changes shaped mid-latitude hydroclimate since the mid-Holocene
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DOI：
10.1016/j.epsl.2020.116293
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发表时间：
2020-07
影响因子：
5.3
通讯作者：
C. Skinner;J. Lora;A. Payne;C. Poulsen
中科院分区：
文献类型：
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作者：
C. Skinner;J. Lora;A. Payne;C. Poulsen
古气候代用指标表明，自全新世中期以来，日照的变化驱动了中纬度地区广泛的水文变化。目前还不清楚如何大气河流（AR），这是今天全球水分运输的基础，可能有助于这些全新世水文气候变化。在这里，我们使用一组气候模型模拟与社区地球系统模型（CESM），并引入AR算法优化识别AR在不同的气候状态下，显示的位置和强度的变化，登陆AR解释了大部分的降水差异全新世中期和工业化前时期在几个中纬度地区。在全新世中期，增强的季节性增加夏季AR蒸汽含量和位移AR向极的前工业化时期的轨迹，特别是在北方半球。因此，在北美西部和东亚的高中纬度沿海地区，AR在中全新世期间占总降水量的10%以上，并且几乎100%的模拟两种气候之间的降水变化。模拟的AR变化是一致的水分敏感的代理记录，并与当今的AR和区域环流之间的关系，增强了信心，AR作为基本的天气机制负责中全新世水文气候异常在几个沿海中纬度地区。结果表明，AR是敏感的背景气候状态，并建议在AR的变化可能有助于水文气候变化在整个地球的过去。
Paleoclimate proxies indicate that changes in insolation since the mid-Holocene have driven widespread hydrologic changes across the midlatitudes. It is unclear how atmospheric rivers (ARs), which are fundamental to global moisture transport today, may have contributed to these Holocene hydroclimate changes. Here, we use a set of climate model simulations with the Community Earth System Model (CESM), and introduce an AR algorithm optimized to identify ARs within different climate states, to show that changes to the location and intensity of landfalling ARs explain the majority of the precipitation difference between the mid-Holocene and the preindustrial period in several midlatitude regions. During the mid-Holocene, enhanced seasonality increased summer season AR vapor content and displaced ARs poleward of their preindustrial period trajectories, especially in the Northern Hemisphere. Consequently, in high midlatitude coastal areas of western North America and East Asia, ARs account for greater than 10% more of total precipitation during the mid-Holocene, and nearly 100% of the simulated change in precipitation between the two climates. The simulated AR changes are consistent with moisture-sensitive proxy records and with present-day relationships between ARs and regional circulation, enhancing confidence that ARs served as the underlying synoptic mechanism responsible for mid-Holocene hydroclimate anomalies in several coastal mid-latitude areas. The results indicate that ARs are sensitive to background climate state, and suggest that changes in ARs may have contributed to hydroclimate changes throughout Earth's past.