在格陵兰冰芯中记录的北大西洋振荡动态
1C. Appenzeller and T. F. Stocker, Climate and Environmental Physics, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland. M. Anklin, Department of Hydrology and Water Resources, University of Arizona, Tucson, AZ 85721, USA.
概括
格陵兰岛的冰芯揭示了北大西洋振荡 (NAO) 是一个间歇性的气候模式,而不是一个持久的. 它的活跃阶段显示了短期的变化,从19世纪中期以来观察到的长期趋势.
科学领域:
- 古气候学 古气候学
- 气候科学 气候科学
- 大气科学 大气科学
背景情况:
- 北大西洋振荡 (NAO) 是一个重要的气候模式,影响北大西洋地区的天气.
- 了解NAO的长期行为和频率对于气候建模和预测至关重要.
- 之前的研究已经探索了NAO变异性,但使用特定的代理数据在几个世纪内进行详细的重建是有价值的.
研究的目的:
- 为了重建跨越过去350年的年度代理北大西洋振荡 (NAO) 指数.
- 调查NAO的间歇性质,确定其主动和被动阶段.
- 为了确定NAO变化的主导频率和时间尺度.
主要方法:
- 使用格陵兰岛精心挑选的冰芯数据作为气候重建的代理.
- 根据分析的冰芯数据,制定NAO的年度指数.
- 应用时间序列分析来识别振荡频率和相位行为.
主要成果:
- 重建的NAO指数表明,NAO是一个间歇性的气候振荡,具有暂时活跃和被动阶段的特点.
- 没有发现单一,持久,多年的NAO频率的证据.
- 在活跃阶段,NAO能量集中在短于大约15年的时间内.
- 自19世纪中叶以来,已经观察到80到90年时间尺度上的变化.
结论:
- 纳奥表现出间歇性行为,而不是持续的长期振荡.
- 在活跃的NAO阶段,短期变化 (少于15年) 主导.
- 更长期的变化 (80-90年) 最近出现了,特别是自19世纪中叶以来,这表明NAO动态的潜在转变.
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