Uncertainties in Projecting Future Changes in Atmospheric Rivers and Their Impacts on Heavy Precipitation over Europe
Uncertainties in Projecting Future Changes in Atmospheric Rivers and Their Impacts on Heavy Precipitation over Europe
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DOI：
10.1175/jcli-d-16-0088.1
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发表时间：
2016-09-15
影响因子：
4.9
通讯作者：
Leung, L. Ruby
中科院分区：
文献类型：
--
作者：
Gao, Yang;Lu, Jian;Leung, L. Ruby
本研究调查北大西洋大气河流（AR）在西欧登陆在现在和未来的气候从耦合模式相互比较项目（CMIP 5）的第5阶段的多模式集合。总体而言，CMIP 5捕捉到了历史登陆AR天的季节和空间变化，大的模型间变异与历史近地面西风急流位置的模型间传播密切相关。在代表性浓度途径8.5（RCP 8.5）下，预计到本世纪末AR频率将显著增加，在AR频率峰值区域（北纬45度-55度）增加127%-275%。虽然热力学起着主导作用，在未来的AR的增加，风的变化与中纬度急流的转变也显着有助于AR的变化，在所有季节的偶极子变化模式。在北大西洋，模型预测的喷流转移与模拟的历史喷流位置密切相关。由于模型主要表现出赤道偏置的历史射流位置，大极向喷流的转变减少AR天南部的历史平均喷流位置，通过喷流位置和AR天之间的动态连接。使用所观察到的历史喷流位置作为紧急约束，动力学效应进一步增加未来AR天以上的赤道侧翼的增加，从economical影响。与目前相比，未来AR所引起的总降水量和极端降水量对季节平均和极端降水量的贡献更大，主要是因为AR频率的增加。虽然AR降水强度一般增加更多的相对于增加的综合水汽输送，AR极端降水强度增加少得多。
This study investigates the North Atlantic atmospheric rivers (ARs) making landfall over western Europe in the present and future climate from the multimodel ensemble of phase 5 of the Coupled Model Intercomparison Project (CMIP5). Overall, CMIP5 captures the seasonal and spatial variations of historical landfalling AR days, with the large intermodel variability strongly correlated with the intermodel spread of historical near-surface westerly jet position. Under representative concentration pathway 8.5 (RCP8.5), AR frequency is projected to increase significantly by the end of this century, with 127%-275% increase at peak AR frequency regions (45 degrees-55 degrees N). While thermodynamics plays a dominant role in the future increase of ARs, wind changes associated with the midlatitude jet shifts also significantly contribute to AR changes, resulting in dipole change patterns in all seasons. In the North Atlantic, the model-projected jet shifts are strongly correlated with the simulated historical jet position. As models exhibit predominantly equatorward biases in the historical jet position, the large poleward jet shifts reduce AR days south of the historical mean jet position through the dynamical connections between the jet positions and AR days. Using the observed historical jet position as an emergent constraint, dynamical effects further increase future AR days over the equatorward flank above the increases from thermodynamical effects. Compared to the present, both total and extreme precipitation induced by ARs in the future contribute more to the seasonal mean and extreme precipitation, primarily because of the increase in AR frequency. While AR precipitation intensity generally increases more relative to the increase in integrated vapor transport, AR extreme precipitation intensity increases much less.