Changes in Madden-Julian Oscillation Precipitation and Wind Variance Under Global Warming
Changes in Madden-Julian Oscillation Precipitation and Wind Variance Under Global Warming
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DOI：
10.1029/2018gl078504
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发表时间：
2018-07-28
影响因子：
5.2
通讯作者：
Maloney, Eric D.
中科院分区：
文献类型：
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作者：
Bui, Hien X.;Maloney, Eric D.
马登-朱利安振荡（MJO）是热带季节内变化的主要模态，对热带和热带外的许多天气和气候现象有着深远的影响。以前使用有限数量的模型进行的研究表明，在温暖的气候中，MJO活动发生了复杂的变化。虽然大多数研究认为，在未来气候变暖的情况下，MJO降水幅度将增加，但其他研究指出，MJO风变率的情况不一定如此。这种区别很重要，因为MJO风波动是通过遥相关对极端天气产生远程影响的原因。在这项研究中，我们研究了MJO降水和风方差的预测变化，在21世纪末的代表性浓度路径8.5使用多模式耦合模型相互比较项目第5阶段的数据集。在全球变暖下，大多数模式显示MJO波段降水方差增加，而风变率减少。在全球变暖下，MJO降水和风方差变化之间的差异是由于在温暖的气候中热带静稳定度的增加。多模式的平均值表明，500百帕垂直热带干静态能量梯度和季节内降水的比例增加20%，500百帕欧米茄波动，与缩放弱温度梯度理论。这些结果意味着，热带静稳定度的增加可能会削弱MJO的能力，影响极端事件在未来温暖的气候，削弱风遥相关，即使MJO降水幅度可能increased.Plain语言摘要Madden朱利安振荡有深远的影响，天气和气候现象的热带和温带地区，包括调制的大气河流，飓风和大气阻塞。我们目前可以利用MJO的知识提前几周预测这种现象。因此，了解MJO在全球变暖下如何变化对于了解其未来影响和预测非常重要。在本文中，我们使用CMIP 5多模式数据集展示了在全球变暖（RCP8.5）的情况下，MJO降水和风方差在21世纪末的变化。我们得出了有趣的结果，全球变暖增强MJO降水幅度，而减弱MJO环流。这一结果很重要，因为MJO与世界其他地区的遥相关是由环流响应介导的，我们的研究结果表明，由于环流减弱，MJO对大气河流，飓风和其他极端事件的影响可能在未来更温暖的气候中变得不可预测。我们也物理解释我们的结果，在温暖的气候中，较弱的环流垂直干静态能量梯度的增加。
The Madden-Julian oscillation (MJO) is the leading mode of tropical intraseasonal variability, having profound impacts on many weather and climate phenomena across the tropics and extratropics. Previous studies using a limited number of models have suggested complex changes in MJO activity in a warmer climate. While most studies have argued that MJO precipitation amplitude will increase in a future warmer climate, others note that this is not necessarily the case for MJO wind variability. This distinction is important since MJO wind fluctuations are responsible for producing remote impacts on extreme weather through teleconnections. In this study, we examine projected changes of MJO precipitation and wind variance at the end of the 21st century in Representative Concentration Pathway 8.5 using the multimodel Coupled Model Intercomparison Project phase 5 data set. Under global warming, most models show an increase in MJO band precipitation variance, while wind variability decreases. The discrepancy between MJO precipitation and wind variance changes under global warming is shown to be due to increases in tropical static stability in a warmer climate. The multimodel mean shows a 20% increase in both the 500-hPa vertical tropical dry static energy gradient and the ratio of intraseasonal precipitation to 500hPa omega fluctuations, consistent with scaling by weak temperature gradient theory. These results imply that tropical static stability increases may weaken the MJO's ability to influence extreme events in future warmer climate by weakening wind teleconnections, even though MJO precipitation amplitude may increase.Plain Language Summary The Madden-Julian oscillation has profound impacts on weather and climate phenomena over the tropical and extratropical regions, including a modulation of atmospheric rivers, hurricanes, and atmospheric blocking. We can currently exploit knowledge of the MJO to predict such phenomena several weeks in advance. Therefore, understanding how the MJO may change under global warming is important to understanding its future impacts and for prediction. In this manuscript, we show how MJO precipitation and wind variance change at the end of the 21st Century under global warming (RCP8.5) using the CMIP5 multi-model dataset. We derive the interesting result that global warming enhances MJO precipitation amplitude while weakening the MJO circulation. This result is important, as MJO teleconnections to other parts of the world are mediated by the circulation response, and our results suggest that MJO impacts on atmospheric rivers, hurricanes, and other extreme events may become less predictable in a future warmer climate due to the weakened circulation. We also physically explain our results by relating weaker circulations to the increase in the vertical dry static energy gradient in a warmer climate.