Future changes in extratropical storm tracks and baroclinicity under climate change
Future changes in extratropical storm tracks and baroclinicity under climate change
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DOI：
10.1088/1748-9326/9/8/084002
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发表时间：
2014-08-01
影响因子：
6.7
通讯作者：
Levermann, Anders
中科院分区：
文献类型：
--
作者：
Lehmann, Jascha;Coumou, Dim;Levermann, Anders
欧亚大陆、澳大利亚和南北美洲的天气在很大程度上受温带风暴路径的强度和位置的控制。未来的气候变化可能会影响这些风暴路径以及相关的能量、动量和水蒸气的输送。最近的许多研究都分析了气候变化下风暴路径的变化，以及这些变化与大气动力学的关系。然而，关于未来气候情景下风暴路径如何变化的不同研究之间仍然存在差异。结果表明，在全球变暖的背景下，CMIP5气候模式预测的中纬度垂直平均风暴路径活动在北方冬季的相对变化很小，但在夏季有明显的减少。南半球的季节变化表现出相反的行为，冬季加剧，夏季没有变化。北部夏季和南部冬季风暴路径的这些明显的季节变化导致未来气候的季节周期放大。类似的变化也出现在中纬度平均增长率最大值上，这是一种结合垂直切变和基于斜压不稳定理论的静态稳定性变化的度量。对风暴路径变化和最大埃迪增长率变化的回归分析表明，在中纬度地区，大多数模式一致认为两者之间存在正相关关系。
The weather in Eurasia, Australia, and North and South America is largely controlled by the strength and position of extratropical storm tracks. Future climate change will likely affect these storm tracks and the associated transport of energy, momentum, and water vapour. Many recent studies have analyzed how storm tracks will change under climate change, and how these changes are related to atmospheric dynamics. However, there are still discrepancies between different studies on how storm tracks will change under future climate scenarios. Here, we show that under global warming the CMIP5 ensemble of coupled climate models projects only little relative changes in vertically averaged mid-latitude mean storm track activity during the northern winter, but agree in projecting a substantial decrease during summer. Seasonal changes in the Southern Hemisphere show the opposite behaviour, with an intensification in winter and no change during summer. These distinct seasonal changes in northern summer and southern winter storm tracks lead to an amplified seasonal cycle in a future climate. Similar changes are seen in the mid-latitude mean Eady growth rate maximum, a measure that combines changes in vertical shear and static stability based on baroclinic instability theory. Regression analysis between changes in the storm tracks and changes in the maximum Eady growth rate reveal that most models agree in a positive association between the two quantities over mid-latitude regions.