Holocene changes in the position and intensity of the southern westerly wind belt
Holocene changes in the position and intensity of the southern westerly wind belt
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DOI：
10.1038/ngeo959
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发表时间：
2010-10-01
影响因子：
18.3
通讯作者：
Steinke, Tatjana
中科院分区：
文献类型：
--
作者：
Lamy, Frank;Kilian, Rolf;Steinke, Tatjana
由于海面温度的变化，南西风带的位置和强度随季节变化。南半球冬季，风带向北扩展，核心风强减弱。相反，在夏季，腰带收缩，核心内的强度增强。然而，自末次盛冰期以来西风的重建表明，单个地点的变化反映了整个南风带的变化(1-4)。在这里，我们利用沉积学和花粉记录，从安第斯山脉迎风面沿线的地点重建了过去 12,500 年的降水模式。这些地点位于目前西风带的核心和北缘，降水几乎完全由风带驱动(5)，可用于重建其强度。我们发现，在整个全新世时期，风力强度在数千年的时间尺度上存在明显的反相位变化，而不是在整个全新世时期一致变化。全新世早期，核心西风风强，北缘西风风弱。我们在全新世晚期观察到相反的模式。由于这种变化类似于现代季节变化，我们认为我们观察到的西风强度变化可以最好地用南太平洋东部海面温度的变化来解释。
The position and intensity of the southern westerly wind belt varies seasonally as a consequence of changes in sea surface temperature. During the austral winter, the belt expands northward and the wind intensity in the core decreases. Conversely, during the summer, the belt contracts, and the intensity within the core is strengthened. Reconstructions of the westerly winds since the last glacial maximum, however, have suggested that changes at a single site reflected shifts throughout the entire southern wind belt(1-4). Here we use sedimentological and pollen records to reconstruct precipitation patterns over the past 12,500 yr from sites along the windward side of the Andes. Precipitation at the sites, located in the present core and northern margin of the westerlies, is driven almost entirely by the wind belt(5), and can be used to reconstruct its intensity. Rather than varying coherently throughout the Holocene epoch, we find a distinct anti-phasing of wind strength between the core and northern margin over multi-millennial timescales. During the early Holocene, the core westerlies were strong whereas the northern margin westerlies were weak. We observe the opposite pattern in the late Holocene. As this variation resembles modern seasonal variability, we suggest that our observed changes in westerly wind strength can best be explained by variations in sea surface temperature in the eastern South Pacific Ocean.