What Drives the North Atlantic Oscillation’s Temperature Anomaly Pattern? Part I: The Growth and Decay of the Surface Air Temperature Anomalies
What Drives the North Atlantic Oscillation’s Temperature Anomaly Pattern? Part I: The Growth and Decay of the Surface Air Temperature Anomalies
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DOI：
10.1175/jas-d-19-0027.1
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发表时间：
2019-12
影响因子：
3.1
通讯作者：
J. P. Clark;S. Feldstein
中科院分区：
文献类型：
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作者：
J. P. Clark;S. Feldstein
合成分析是用来检查的物理过程，驱动与北大西洋涛动（NAO）的地面气温异常模式的增长和衰减。使用热力学能量方程，欧洲中期天气预报中心在他们的再分析模型中实施，我们表明，平流的气候温度场的异常风驱动的地面空气温度异常模式的两个NAO阶段。非绝热过程的存在与这种温度平流强烈相反，并最终导致地面气温异常恢复到其气候学值。具体而言，在格陵兰岛，欧洲和美国，长波加热/冷却反对水平温度平流，而在北方非洲垂直混合反对水平温度平流。尽管皮肤温度和表面空气温度异常模式之间存在明显的空间对应关系，但驱动这两种与NAO相关的温度异常的物理过程是不同的。地表温度距平型是由向下长波辐射驱动的，而地面气温距平型是由水平温度平流驱动的。这意味着，表面能量收支，虽然是一个有用的诊断工具，了解皮肤温度的变化，不应该被用来了解表面空气温度的变化。
Composite analysis is used to examine the physical processes that drive the growth and decay of the surface air temperature anomaly pattern associated with the North Atlantic Oscillation (NAO). Using the thermodynamic energy equation that the European Centre for Medium-Range Weather Forecasts implements in their reanalysis model, we show that advection of the climatological temperature field by the anomalous wind drives the surface air temperature anomaly pattern for both NAO phases. Diabatic processes exist in strong opposition to this temperature advection and eventually cause the surface air temperature anomalies to return to their climatological values. Specifically, over Greenland, Europe, and the United States, longwave heating/cooling opposes horizontal temperature advection while over northern Africa vertical mixing opposes horizontal temperature advection. Despite the pronounced spatial correspondence between the skin temperature and surface air temperature anomaly patterns, the physical processes that drive these two temperature anomalies associated with the NAO are found to be distinct. The skin temperature anomaly pattern is driven by downward longwave radiation whereas stated above, the surface air temperature anomaly pattern is driven by horizontal temperature advection. This implies that the surface energy budget, although a useful diagnostic tool for understanding skin temperature changes, should not be used to understand surface air temperature changes.