Observational evidence of European summer weather patterns predictable from spring.
Observational evidence of European summer weather patterns predictable from spring.
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欧洲夏季天气模式的观察证据可以从春季预测。
DOI：
10.1073/pnas.1713146114
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发表时间：
2018-01-02
影响因子：
11.1
通讯作者：
Dong B
中科院分区：
文献类型：
--
作者：
Ossó A;Sutton R;Shaffrey L;Dong B
提前几个月预报夏季天气模式对于从旅游业到农业、水资源管理、能源生产、建筑和零售等广泛的应用具有重要价值。然而，动力学模式对欧洲夏季的季节性预报技巧很少。在这里，我们分析了大气和海洋观测，并确定了西欧夏季大气环流的特定模式的证据是可预测的，从以前的春天北大西洋海面温度，并确定所涉及的机制。大气模式对不列颠群岛和法国北海岸的降雨量有着特别强烈的影响，我们发现，只要有相当的技巧，也可以提前几个月预测降雨量。提前几个月预报夏季天气模式将具有广泛的应用价值。然而，欧洲夏季的季节性动力模型预测的技巧很少，特别是降雨。目前尚不清楚这种低技能是否反映了夏季天气固有的不可预测性，或者是目前预报系统薄弱的结果。在这里，我们分析了大气和海洋观测，并确定了夏季大气环流的特定模式-夏季东大西洋（SEA）模式-是可预测的前一个春天的证据。北大西洋海表温度在3月至4月的指数可以预测在7月至8月的SEA模式与0.6以上的交叉验证的相关技能。我们的分析表明，海表温度影响大气环流和急流在北大西洋的位置。SEA模式对不列颠群岛的降雨量有特别强的影响，我们发现这也可以提前几个月预测，显著技能为0.56。我们的研究结果有直接的应用经验预测英国，爱尔兰和北方法国夏季降雨量，也表明，目前的动力学模型预测系统有很大的改进潜力。
Forecasts of summer weather patterns months in advance would be of great value for a wide range of applications, from tourism to agriculture, water resource management, energy production, construction, and retail. However, dynamical model seasonal forecasts for European summers have very little skill. Here, we analyze atmosphere and ocean observations and identify evidence that a specific pattern of summertime atmospheric circulation over Western Europe is predictable from the previous spring North Atlantic sea-surface temperatures, and identify the mechanism involved. The atmospheric pattern has a particularly strong influence on rainfall in the British Isles and in the north coast of France, which we find can also be predicted months ahead with significant skill. Forecasts of summer weather patterns months in advance would be of great value for a wide range of applications. However, seasonal dynamical model forecasts for European summers have very little skill, particularly for rainfall. It has not been clear whether this low skill reflects inherent unpredictability of summer weather or, alternatively, is a consequence of weaknesses in current forecast systems. Here we analyze atmosphere and ocean observations and identify evidence that a specific pattern of summertime atmospheric circulation––the summer East Atlantic (SEA) pattern––is predictable from the previous spring. An index of North Atlantic sea-surface temperatures in March–April can predict the SEA pattern in July–August with a cross-validated correlation skill above 0.6. Our analyses show that the sea-surface temperatures influence atmospheric circulation and the position of the jet stream over the North Atlantic. The SEA pattern has a particularly strong influence on rainfall in the British Isles, which we find can also be predicted months ahead with a significant skill of 0.56. Our results have immediate application to empirical forecasts of summer rainfall for the United Kingdom, Ireland, and northern France and also suggest that current dynamical model forecast systems have large potential for improvement.
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