Insolation-driven changes in atmospheric circulation over the past 116,000 years in subtropical Brazil
Insolation-driven changes in atmospheric circulation over the past 116,000 years in subtropical Brazil
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DOI：
10.1038/nature03365
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发表时间：
2005-03-03
期刊：
影响因子：
64.8
通讯作者：
Viana, O
中科院分区：
文献类型：
--
作者：
Cruz, FW;Burns, SJ;Viana, O
在末次冰期，大的千年尺度温度振荡--“丹斯加德/厄施格”周期--是北方半球从高纬度到热带气候档案中的主要气候信号（1-6）。但是，这些突然的气候变化的影响是否延伸到热带和亚热带南半球，那里的日照变化被认为是气候的主要直接强迫，仍然不清楚。在这里，我们提出了一个高分辨率的氧同位素记录的U/Th年代的石笋从亚热带巴西南部，涵盖了过去的116,200年。氧同位素特征随源区和该地区降雨量的变化而变化，因此记录了南美洲上空大气环流和对流强度的变化。我们发现，这些变化的降雨来源和数量主要是由夏季太阳辐射，这是由地球的岁差周期控制。在我们的记录中可以检测到Dansgaard/ Oeschger循环，因此我们确认它们也影响热带水文循环，但在巴西南部亚热带地区，千年尺度的气候变化并不像在北方半球那样占主导地位。
During the last glacial period, large millennial- scale temperature oscillations - the 'Dansgaard/Oeschger' cycles - were the primary climate signal in Northern Hemisphere climate archives from the high latitudes to the tropics(1-6). But whether the influence of these abrupt climate changes extended to the tropical and subtropical Southern Hemisphere, where changes in insolation are thought to be the main direct forcing of climate, has remained unclear. Here we present a high-resolution oxygen isotope record of a U/Th-dated stalagmite from subtropical southern Brazil, covering the past 116,200 years. The oxygen isotope signature varies with shifts in the source region and amount of rainfall in the area, and hence records changes in atmospheric circulation and convective intensity over South America. We find that these variations in rainfall source and amount are primarily driven by summer solar radiation, which is controlled by the Earth's precessional cycle. The Dansgaard/ Oeschger cycles can be detected in our record and therefore we confirm that they also affect the tropical hydrological cycle, but that in southern subtropical Brazil, millennial-scale climate changes are not as dominant as they are in the Northern Hemisphere.