Fluctuations in Closed-Basin Lakes as An Indicator of Past Atmospheric Circulation Patterns
Fluctuations in Closed-Basin Lakes as An Indicator of Past Atmospheric Circulation Patterns
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DOI：
10.1007/978-94-009-6954-4_26
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发表时间：
1983
期刊：
影响因子：
--
通讯作者：
F. Street-Perrott;N. Roberts
中科院分区：
文献类型：
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作者：
F. Street-Perrott;N. Roberts
目前，湖泊面积的最大值与赤道槽和中纬度西风带的纬度平均位置有关。这种关联适用于过去18000年中湖泊相对范围的变化，以推断过去大气环流的变化。该分析是基于非洲和欧亚大陆西部的大量14 C测年湖平面层序。我们推断，最大冰期之后的时期大约是。18 000年BP的特点是在热带地区的干旱增加，达到顶峰，在大约14 000 - 12 500年BP时，大气水分辐合和径流达到最低值，几乎整个研究区。在12500年和5000年BP之间，在非洲和阿拉伯半岛形成了一个广阔的湖泊带。它不规则地向北迁移到北纬16.5度，然后在5000 - 4000年BP后迅速解体。这种早期冰后期大陆水文循环的加剧主要归因于非洲和阿拉伯半岛上空的季风环流增强，可能伴随着平均ITCZ的北移。它被打断了两次长时间的干旱集中在10 200和7400年BP。讨论了这些气候突变事件的成因。
At the present day, maxima in the areal extent of lakes are associated with the latitudinal mean positions of the equatorial trough and the mid-latitude westerlies. This association is applied to variations in the relative extent of lakes during the last 18 000 years in order to deduce past changes in atmospheric circulation. The analysis is based on a large number of14C-dated lake-level sequences from Africa and western Eurasia. We infer that the period following the glacial maximum atca. 18 000 yr BP was characterized by increasing aridity in the tropics, culminating at around 14 000 – 12 500 yr BP when atmospheric moisture convergence and runoff reached minimum values over almost the entire study area. Between 12 500 and 5000 yr BP, a broad belt of expanded lakes developed in Africa and Arabia. It migrated irregularly northwards to a latitude of 16.5 N and then disintegrated rapidly after 5000 – 4000 yr BP. This early postglacial intensification of the continental hydrological cycle is attributed primarily to an enhanced monsoonal circulation over Africa and Arabia, probably accompanied by a northward shift of the mean ITCZ. It was interrupted by two episodes of prolonged drought centred on 10 200 and 7400 yr BP. The causes of these abrupt climatic events are discussed.