Atlantic forcing of Western Mediterranean winter rain minima during the last 12,000 years
Atlantic forcing of Western Mediterranean winter rain minima during the last 12,000 years
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DOI：
10.1016/j.quascirev.2016.11.037
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发表时间：
2017-02
影响因子：
4
通讯作者：
C. Zielhofer;W. Fletcher;S. Mischke;M. Batist;J. Campbell;S. Joannin;R. Tjallingii;N. Hamouti;A. Junginger;A. Stele;J. Bussmann;B. Schneider;T. Lauer;K. Spitzer;M. Strupler;T. Brachert;Abdeslam Mikdad
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文献类型：
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作者：
C. Zielhofer;W. Fletcher;S. Mischke;M. Batist;J. Campbell;S. Joannin;R. Tjallingii;N. Hamouti;A. Junginger;A. Stele;J. Bussmann;B. Schneider;T. Lauer;K. Spitzer;M. Strupler;T. Brachert;Abdeslam Mikdad
高分辨率连续档案的有限可用性、时间控制的不足以及复杂的水文气候强迫机制导致西地中海古水文重建存在许多不确定性。在这项研究中，我们展示了北非中部阿特拉斯（大西洋、西地中海和撒哈拉气团轨迹的过渡区）西迪阿里湖新近恢复的19.63米长的岩心。基于磁化率、碳酸盐和总有机碳含量、岩心扫描和定量XRF、介壳类稳定同位素、木炭计数、雪松孢粉丰度和第一组硅藻数据，我们采用多代理方法重建了过去12000年来西地中海的水文气候变化、季节性和强迫机制。基于AMS14C定年花粉浓缩物的稳健年代学模型支持了我们的高分辨率多代理研究。长期趋势表明，在新仙女木期末期、全新世中期6.6 ~ 5.4 cal ka BP以及过去3000年间，湖泊水位较低。相比之下，早全新世和中全新世湖泊水位大多较高。记录还显示，地中海西部冬季降雨的次千年至百年尺度减少为11.4、10.3、9.2、8.2、7.2、6.6、6.0、5.4、5.0、4.4、3.5、2.9、2.2、1.9、1.7、1.5、1.0、0.7和0.2 cal ka BP。全新世早期冬季降水极小期与北大西洋次极区降温事件和千年尺度融水排放相一致。我们的代理参数到目前为止还没有显示出撒哈拉气团对北非地中海水文气候的明显影响。然而，在非洲湿润期（~ 5 ka）结束时的一次显著的水文气候变化表明气候强迫机制发生了变化。中阿特拉斯晚全新世气候变率具有多百年尺度的nao型特征，大西洋变冷和西地中海冬雨最大值通常与太阳极小期相关。
The limited availability of high-resolution continuous archives, insufficient chronological control, and complex hydro-climatic forcing mechanisms lead to many uncertainties in palaeo-hydrological reconstructions for the Western Mediterranean. In this study we present a newly recovered 19.63 m long core from Lake Sidi Ali in the North African Middle Atlas, a transition zone of Atlantic, Western Mediterranean and Saharan air mass trajectories. With a multi-proxy approach based on magnetic susceptibility, carbonate and total organic C content, core-scanning and quantitative XRF, stable isotopes of ostracod shells, charcoal counts,Cedruspollen abundance, and a first set of diatom data, we reconstruct Western Mediterranean hydro-climatic variability, seasonality and forcing mechanisms during the last 12,000 yr. A robust chronological model based on AMS14C dated pollen concentrates supports our high-resolution multi-proxy study. Long-term trends reveal low lake levels at the end of the Younger Dryas, during the mid-Holocene interval 6.6 to 5.4 cal ka BP, and during the last 3000 years. In contrast, lake levels are mostly high during the Early and Mid-Holocene. The record also shows sub-millennial- to centennial-scale decreases in Western Mediterranean winter rain at 11.4, 10.3, 9.2, 8.2, 7.2, 6.6, 6.0, 5.4, 5.0, 4.4, 3.5, 2.9, 2.2, 1.9, 1.7, 1.5, 1.0, 0.7, and 0.2 cal ka BP. Early Holocene winter rain minima are in phase with cooling events and millennial-scale meltwater discharges in the sub-polar North Atlantic. Our proxy parameters do not show so far a clear impact of Saharan air masses on Mediterranean hydro-climate in North Africa. However, a significant hydro-climatic shift at the end of the African Humid Period (∼5 ka) indicates a change in climate forcing mechanisms. The Late Holocene climate variability in the Middle Atlas features a multi-centennial-scale NAO-type pattern, with Atlantic cooling and Western Mediterranean winter rain maxima generally associated with solar minima.