The influence of the stratospheric state on North Atlantic weather regimes
The influence of the stratospheric state on North Atlantic weather regimes
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DOI：
10.1002/qj.3280
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发表时间：
2018-04
影响因子：
8.9
通讯作者：
A. Charlton-Perez;L. Ferranti;R. Lee
中科院分区：
文献类型：
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作者：
A. Charlton-Perez;L. Ferranti;R. Lee
平流层-对流层耦合通常是从环模及其动力学的角度来考虑的。尽管这种方法有明显的好处，但最近的工作强调了大西洋盆地比太平洋盆地对流层对平流层变化的敏感性更高。本文提出了一种理解平流层-对流层耦合的新方法，重点研究了平流层状态对北大西洋天气状况(11月至3月延冬期间)的影响。量化了平流层低层涡旋强度对四种常用对流层天气状况的影响。北大西洋涛动的负位相对平流层状态最敏感，在弱涡旋条件下33%的天数出现在平流层状态，而在强涡条件下只出现5%的天数。北大西洋涛动和大西洋脊区正位相的敏感性相对较弱。对于北大西洋涛动系统，平流层条件改变了保留在每个系统的概率和从其他系统过渡到该系统的概率。为了进一步量化对流层天气状况对低平流层状态的敏感性，发展了一种Logistic回归模式。Logistic回归模型预测，平流层涡旋强度每减少一个标准差，北大西洋涛动转换到负位相的概率将增加40%-60%。同样，它预测平流层涡旋强度每增加一个标准差，转换到北大西洋涛动正相的概率将增加10-30%。通过对同一Logistic回归模型的拟合，发现欧洲中期天气预报综合预报系统模式的平流层-对流层耦合与再分析资料是一致的。
Stratosphere–troposphere coupling is often viewed from the perspective of the annular modes and their dynamics. Despite the obvious benefits of this approach, recent work has emphasised the greater tropospheric sensitivity to stratospheric variability in the Atlantic basin than in the Pacific basin. In this study, a new approach to understanding stratosphere–troposphere coupling is proposed, with a focus on the influence of the stratospheric state on North Atlantic weather regimes (during extended winter, November to March). The influence of the strength of the lower‐stratospheric vortex on four commonly used tropospheric weather regimes is quantified. The negative phase of the North Atlantic Oscillation is most sensitive to the stratospheric state, occurring on 33% of days following weak vortex conditions but on only 5% of days following strong vortex conditions. An opposite and slightly weaker sensitivity is found for the positive phase of the North Atlantic Oscillation and the Atlantic Ridge regime. For the North Atlantic Oscillation regimes, stratospheric conditions change both the probability of remaining in each regime and the probability of transitioning to that regime from others. A logistic regression model is developed to further quantify the sensitivity of tropospheric weather regimes to the lower stratospheric state. The logistic regression model predicts an increase of 40–60% in the probability of transition to the negative phase of the North Atlantic Oscillation for a one standard deviation reduction in the strength of the stratospheric vortex. Similarly it predicts a 10–30% increase in the probability of transition to the positive phase of the North Atlantic Oscillation for a one standard deviation increase in the strength of the stratospheric vortex. The stratosphere–troposphere coupling in the European Centre for Medium‐range Weather Forecasts Integrated Forecasting System model is found to be consistent with the re‐analysis data by fitting the same logistic regression model.