Changes in ventilation of the Mediterranean Sea during the past 25 year
Changes in ventilation of the Mediterranean Sea during the past 25 year
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DOI：
10.5194/os-10-1-2014
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发表时间：
2013-08
期刊：
影响因子：
3.2
通讯作者：
A. Schneider;T. Tanhua;W. Roether;R. Steinfeldt
中科院分区：
文献类型：
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作者：
A. Schneider;T. Tanhua;W. Roether;R. Steinfeldt
抽象。在过去的几十年里，地中海的翻转环流发生了重大变化，最突出的现象是20世纪90年代初的东地中海瞬变（EMT）和21世纪中期的西地中海过渡（WMT）。在这两次事件中，形成了异常大量的深水，在EMT事件中，深水形成区域从亚得里亚海转移到爱琴海。在这里，我们合成了一个独特的收集瞬态示踪剂（CFC-12，SF6和氚）的数据，从1987年和2011年之间进行的9次巡航，并使用这些数据来确定地中海通风的时间变化。我们还讨论了偏见和技术问题，瞬态示踪剂为基础的年龄所产生的不同的输入历史随着时间的推移，特别是在时间依赖性通气的情况下。我们观察到一段时间的低通气在东部（黎凡特）盆地后，它是通风的EMT，使年龄的深水随着时间的推移而增加。另一方面，在爱奥尼亚海，我们看到2001年后通风增加的证据，表明亚得里亚海的深水形成重新开始。这也反映在自20世纪80年代末以来，亚得里亚海深水年龄的增加和亚得里亚海深水年龄的减少。在西地中海深水盆地，我们看到在WMT期间最近通风的沃茨的大量输入。这种信号在第勒尼安海还不明显，那里的通风似乎是相当恒定的，因为EMT。此外，西部阿尔沃兰海并没有表现出任何通风的时间趋势。
Abstract. Significant changes in the overturning circulation of the Mediterranean Sea has been observed during the last few decades, the most prominent phenomena being the Eastern Mediterranean Transient (EMT) in the early 1990s and the Western Mediterranean Transition (WMT) during the mid-2000s. During both of these events unusually large amounts of deep water were formed, and in the case of the EMT, the deep water formation area shifted from the Adriatic to the Aegean Sea. Here we synthesize a unique collection of transient tracer (CFC-12, SF6 and tritium) data from nine cruises conducted between 1987 and 2011 and use these data to determine temporal variability of Mediterranean ventilation. We also discuss biases and technical problems with transient tracer-based ages arising from their different input histories over time; particularly in the case of time-dependent ventilation. We observe a period of low ventilation in the deep eastern (Levantine) basin after it was ventilated by the EMT so that the age of the deep water is increasing with time. In the Ionian Sea, on the other hand, we see evidence of increased ventilation after year 2001, indicating the restarted deep water formation in the Adriatic Sea. This is also reflected in the increasing age of the Cretan Sea deep water and decreasing age of Adriatic Sea deep water since the end of the 1980s. In the western Mediterranean deep basin we see the massive input of recently ventilated waters during the WMT. This signal is not yet apparent in the Tyrrhenian Sea, where the ventilation seems to be fairly constant since the EMT. Also the western Alboran Sea does not show any temporal trends in ventilation.