Observed and projected decrease in Northern Hemisphere extratropical cyclone activity in summer and its impacts on maximum temperature
Observed and projected decrease in Northern Hemisphere extratropical cyclone activity in summer and its impacts on maximum temperature
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DOI：
10.1002/2016gl068172
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发表时间：
2016-03-16
影响因子：
5.2
通讯作者：
Yau, Albert M. W.
中科院分区：
文献类型：
--
作者：
Chang, Edmund K. M.;Ma, Chen-Geng;Yau, Albert M. W.
温带气旋造成了中纬度地区的大部分高影响天气。随着温室气体的增加，高纬度变暖加剧将导致气旋活动减弱。这里我们展示了1979至2014年间，北半球夏季强气旋的数量以每十年4%的速度减少，北美东北部附近的减少幅度更大。气候模型预测夏季气旋活动会减少，但观测到的减少速度接近最快的预测。夏季气旋活动减少将导致云量减少，导致最高气温上升，可能会使一些地区的最高气温上升0.5K或更多。我们还表明，气候模式在模拟气旋活动与云量之间的正相关关系方面可能存在偏差，可能低估了气旋减少对加剧未来最高气温上升的影响。
Extratropical cyclones cause much of the high-impact weather over the midlatitudes. With increasing greenhouse gases, enhanced high-latitude warming will lead to weaker cyclone activity. Here we show that between 1979 and 2014, the number of strong cyclones in Northern Hemisphere in summer has decreased at a rate of 4% per decade, with even larger decrease found near northeastern North America. Climate models project a decrease in summer cyclone activity, but the observed decreasing rate is near the fastest projected. Decrease in summer cyclone activity will lead to decrease in cloud cover, giving rise to higher maximum temperature, potentially enhancing the increase in maximum temperature by 0.5K or more over some regions. We also show that climate models may have biases in simulating the positive relationship between cyclone activity and cloud cover, potentially underestimating the impacts of cyclone decrease on accentuating the future increase in maximum temperature.