Underlying causes of Eurasian midcontinental aridity in simulations of mid-Holocene climate.
Underlying causes of Eurasian midcontinental aridity in simulations of mid-Holocene climate.
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DOI：
10.1002/2017gl074476
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发表时间：
2017-09-16
影响因子：
5.2
通讯作者：
Izumi K
中科院分区：
文献类型：
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作者：
Bartlein PJ;Harrison SP;Izumi K
气候模型模拟一致显示，在全新世中期，欧亚大陆中部的夏季干燥而温暖，这与古环境观测结果不一致。模拟的气候结果从纬向温度梯度的减少，减弱西风气流，减少在大陆中部的水分通量和降水。因此，显热比蒸发和潜热更受欢迎，导致大量的地表驱动大气变暖。因此，与古环境证据的差异最初是由模拟环流中的问题引起的，并因来自陆地表面的反馈而加剧。该地区也比工业化前控制模拟中的观测结果更干燥和温暖，这种偏差也以同样的方式出现：纬向流以及因此进入中大陆的水分通量太弱，来自陆地表面的反馈导致表面驱动的变暖。这些分析表明，有必要改善影响西风环流强度的气候模式的那些方面。CMIP 5/PMIP 3中全新世欧亚大陆模拟相对于古气候观测结果过于干燥和过于温暖这种不匹配归因于模拟弱西风和水分通量，并被地表能量平衡和地表水平衡反馈放大。
Climate model simulations uniformly show drier and warmer summers in the Eurasian midcontinent during the mid‐Holocene, which is not consistent with paleoenvironmental observations. The simulated climate results from a reduction in the zonal temperature gradient, which weakens westerly flow and reduces moisture flux and precipitation in the midcontinent. As a result, sensible heating is favored over evaporation and latent heating, resulting in substantial surface‐driven atmospheric warming. Thus, the discrepancy with the paleoenvironmental evidence arises initially from a problem in the simulated circulation and is exacerbated by feedback from the land surface. This region is also drier and warmer than indicated by observations in the preindustrial control simulations, and this bias arises in the same way: zonal flow and hence moisture flux into the midcontinent are too weak, and feedback from the land surface results in surface‐driven warming. These analyses suggest the need to improve those aspects of climate models that affect the strength of westerly circulation. CMIP5/PMIP3 mid‐Holocene simulations in the Eurasian midcontinent are too dry and too warm relative to paleoclimatic observations This mismatch is attributed to simulation of weak westerlies and moisture fluxes, amplified by surface‐energy‐balance and surface‐water‐balance feedback The mismatch is similar to bias in climate model simulations for the present day