Palaeolimnological evidence for an east-west climate see-saw in the Mediterranean since AD 900
Palaeolimnological evidence for an east-west climate see-saw in the Mediterranean since AD 900
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DOI：
10.1016/j.gloplacha.2011.11.002
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发表时间：
2012-03
影响因子：
3.9
通讯作者：
N. Roberts;A. Moreno;B. Valero-Garcés;J. Corella;Matthew D. Jones;S. Allcock;J. Woodbridge;M. Morellón;J. Luterbacher;E. Xoplaki;M. Türkeş
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文献类型：
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作者：
N. Roberts;A. Moreno;B. Valero-Garcés;J. Corella;Matthew D. Jones;S. Allcock;J. Woodbridge;M. Morellón;J. Luterbacher;E. Xoplaki;M. Türkeş
在仪器记录期间，北大西洋涛动（NAO）强烈影响西地中海的年际降水变化，而盆地东部的一些地区的降水和大气压力显示出反相位关系。在这里，我们探讨如何NAO和其他大气环流模式在中世纪气候异常（MCA）和小冰期（LIA）的较长时间尺度上运行。高分辨率的古湖沼证据，从地中海盆地的两端，补充其他古气候数据，用于跟踪区域水文气候条件的变化。自公元900年以来，西班牙东北部的Estanya和Montcortés湖以及土耳其中部的Nar湖的多种地球化学，沉积学，同位素和古生态学代理已经在十年的时间间隔内相互关联。这些旱地湖泊通过调整水位和盐度敏感地捕捉到降水/蒸发平衡的变化，对于重建十年至百年时间尺度的变化特别有价值。伊比利亚湖泊在11至13世纪与MCA同步显示出较低的水位和较高的盐度，并且在LIA（15至19世纪）期间通常更潮湿。这种模式在摩洛哥的树木年轮记录和西地中海的海洋岩芯中也很明显。在地中海东部，来自土耳其、希腊和黎凡特的古气候记录显示，LIA期间的水文气候条件普遍较为干燥，MCA期间则较为湿润。这意味着在过去的1100年里，两极气候的跷跷板一直在地中海运作。然而，虽然西地中海干旱出现一致的持续积极NAO状态在MCA，模式是不太清楚，在地中海东部。在这里，MCA期间冬季降水量较高的最有力证据来自地中海盆地东北部的土耳其中部。这反过来又意味着，LIA/MCA水文气候模式在地中海是由不同的气候模式的组合，沿着与主要的物理地理控制，而不是由NAO强迫单独，或NAO和它的遥相关的字符一直是非平稳的。
During the period of instrumental records, the North Atlantic Oscillation (NAO) has strongly influenced inter-annual precipitation variations in the western Mediterranean, while some eastern parts of the basin have shown an anti-phase relationship in precipitation and atmospheric pressure. Here we explore how the NAO and other atmospheric circulation modes operated over the longer timescales of the Medieval Climate Anomaly (MCA) and Little Ice Age (LIA). High-resolution palaeolimnological evidence from opposite ends of the Mediterranean basin, supplemented by other palaeoclimate data, is used to track shifts in regional hydro-climatic conditions. Multiple geochemical, sedimentological, isotopic and palaeoecological proxies from Estanya and Montcortés lakes in northeast Spain and Nar lake in central Turkey have been cross-correlated at decadal time intervals since AD 900. These dryland lakes capture sensitively changes in precipitation/evaporation (P/E) balance by adjustments in water level and salinity, and are especially valuable for reconstructing variability over decadal–centennial timescales. Iberian lakes show lower water levels and higher salinities during the 11th to 13th centuries synchronous with the MCA and generally more humid conditions during the ‘LIA’ (15th–19th centuries). This pattern is also clearly evident in tree-ring records from Morocco and from marine cores in the western Mediterranean Sea. In the eastern Mediterranean, palaeoclimatic records from Turkey, Greece and the Levant show generally drier hydro-climatic conditions during the LIA and a wetter phase during the MCA. This implies that a bipolar climate see-saw has operated in the Mediterranean for the last 1100years. However, while western Mediterranean aridity appears consistent with persistent positive NAO state during the MCA, the pattern is less clear in the eastern Mediterranean. Here the strongest evidence for higher winter season precipitation during the MCA comes from central Turkey in the northeastern sector of the Mediterranean basin. This in turn implies that the LIA/MCA hydro-climatic pattern in the Mediterranean was determined by a combination of different climate modes along with major physical geographical controls, and not by NAO forcing alone, or that the character of the NAO and its teleconnections have been non-stationary.