Journal of Geophysical Research: Atmospheres Simulating the extreme 2013/2014 winter in a future climate
Journal of Geophysical Research: Atmospheres Simulating the extreme 2013/2014 winter in a future climate
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地球物理研究杂志：大气模拟未来气候中的 2013/2014 年极端冬季
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通讯作者：
D. Glebatis
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作者：
A. Polednak;D. Janerich;D. Glebatis
2013/2014年冬季在北美和西欧观察到的极端天气如何在温暖的气候中表现出来？在这里，强迫敏感性方法被用来计算最佳模式的趋势扰动，导致在模拟中，其上层大气环流的方向转移到2014年1月的急流模式。当应用到一个模拟运行在当今条件下的主要特征的观察，这一事件的再现，如更多的纬向位置和强度增加的中纬度北大西洋风暴轴，在北美的异常温度模式，并在欧洲部分地区的过度降水。当这种方法应用于未来更温暖的气候时，北大西洋风暴路径会变得更加纬向，但其强度不会像现在的模拟中所获得的那样显著增加。尽管极地空气向南平流进入美国东北部，这也发生在2013/2014年冬季，但由于北极的扩大，未来气候中相关的温度下降比现在的气候要少。美国东北部气温下降幅度较小，导致海陆温度对比较小，斜压不稳定性较小，中纬度风暴增加幅度较小。虽然人们可能预计未来增加的大气水分含量会增加净降水量，但对于这一特定事件，这一效应被动力学抵消，导致未来模拟中的降水量净增加与目前相似。
How would the spell of extreme weather observed over North America and western Europe during the 2013/2014 winter manifest itself in a warmer climate? Here a forced sensitivity method is used to calculate optimal model tendency perturbations which result in a simulation which has its upper atmospheric circulation shifted in the direction of the January 2014 jet stream pattern. When applied to a simulation run under present-day conditions the main features of the observations of this event are reproduced, such as the more zonal position and increased strength of the midlatitude North Atlantic storm track, the anomalous temperature pattern over North America, and the excessive precipitation in parts of Europe. When this method is applied to a future warmer climate, the North Atlantic storm track changes to a more zonal orientation, but its strength does not see the significant increase that is obtained in the present-day simulations. Despite southward advection of polar air into northeastern America, which has also occurred during the 2013/2014 winter, the associated drop in temperature is less in the future climate compared to the present-day climate because of Arctic amplification. The less steep drop in temperatures over northeastern America leads to a smaller land-sea temperature contrast, less baroclinic instability, and a reduced increase of midlatitude storminess. While one may expect the future increased atmospheric moisture content to augment the net precipitation, for this specific event, this effect is counterbalanced by the dynamics, leading to a similar net increase in precipitation in the future simulations compared to the present day.