Coastal Sea Level Observations Record the Twentieth-Century Enhancement of Decadal Climate Variability
Coastal Sea Level Observations Record the Twentieth-Century Enhancement of Decadal Climate Variability
复制标题
沿海海平面观测记录了二十世纪十年间气候变化的增强
DOI：
10.1175/jcli-d-22-0451.1
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发表时间：
2023
影响因子：
4.9
通讯作者：
Little, Christopher M.
中科院分区：
文献类型：
--
作者：
Little, Christopher M.
已注意到20世纪年代际气候变率幅度的变化，大部分证据来自热带太平洋海面温度记录。然而，大多数仪器记录的长度、空间覆盖和稳定性不足以可靠地识别这种非平稳性，或解决其全球空间结构。在这里，我们发现潮汐计提供的长期、稳定的观测平台揭示了1960年至2000年间沿海海平面（ζ）年代际（11 - 14年）变率的幅度和空间相干性的急剧增加。在这一时期，北美西部的ζ与澳大利亚悉尼的ζ约处于非相位，并领先美国东北部的ζ约1-2年。这些地区的年代际变化的幅度和时间与大气变率的变化一致。具体来说，赤道中部太平洋的风应力和拉布拉多海的热通量是高度相干的，并且在年代际功率上表现出同期的数量级增加。这些统计关系有一个机制基础：已知沿北美西部海岸线，赤道风会沿着赤道和海岸波导驱动快速传播的ζ信号，而拉布拉多海热通量和美国东北部之间1 - 2年的滞后与远程强迫、浮力驱动的机制相一致。因此，潮汐计为20世纪下半叶在年代际时间尺度上盆地间一致性的增加提供了强有力的独立支持，对气候和海平面变率的解释和预测都有影响。年代际气候变率影响许多自然灾害（如干旱）发生的频率和严重程度，对人类和生态造成相当大的影响。理解观测到的变化和预测未来的影响依赖于对物理过程及其变异性和随时间关系的任何变化的理解。然而，识别这种变化需要非常长的观测记录。本文利用大量的验潮仪记录表明，在20世纪下半叶，在广泛分散的地理位置，沿海海平面的年代际时间尺度变化急剧增加。增加的原因是大气压力、风和海面温度变率的幅度、空间格局和盆地间相干性的变化。
Changes in the amplitude of decadal climate variability over the twentieth century have been noted, with most evidence derived from tropical Pacific sea surface temperature records. However, the length, spatial coverage, and stability of most instrumental records are insufficient to robustly identify such nonstationarity, or resolve its global spatial structure. Here, it is found that the long-term, stable, observing platform provided by tide gauges reveals a dramatic increase in the amplitude and spatial coherence of decadal (11–14-yr period) coastal sea level (ζ) variability between 1960 and 2000. During this epoch, western North Americanζwas approximately out of phase withζin Sydney, Australia, and led northeastern U.S.ζby approximately 1–2 years. The amplitude and timing of changes in decadalζvariability in these regions are consistent with changes in atmospheric variability. Specifically, central equatorial Pacific wind stress and Labrador Sea heat flux are highly coherent and exhibit contemporaneous, order-of-magnitude increases in decadal power. These statistical relationships have a mechanistic underpinning: Along the western North American coastline, equatorial winds are known to drive rapidly propagatingζsignals along equatorial and coastal waveguides, while a 1–2-yr lag between Labrador Sea heat fluxes and northeastern United Statesζis consistent with a remotely forced, buoyancy-driven, mechanism. Tide gauges thus provide strong independent support for an increase in interbasin coherence on decadal time scales over the second half of the twentieth century, with implications for both the interpretation and prediction of climate and sea level variability.Significance StatementDecadal climate variability influences the frequency and severity of many natural hazards (e.g., drought), with considerable human and ecological impacts. Understanding observed changes and predicting future impacts relies upon an understanding of the physical processes and any changes in their variability and relationship over time. However, identifying such changes requires very long observational records. This paper leverages a large set of tide gauge records to show that decadal time scale coastal sea level variability increased dramatically in the second half of the twentieth century, in widely separated geographic locations. The increase was driven by a shift in the amplitude, spatial pattern, and interbasin coherence of atmospheric pressure, wind, and sea surface temperature variability.