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Insolation-driven changes in atmospheric circulation over the past 116,000 years in subtropical Brazil

机译：在亚热带巴西，过去116,000年中，受日晒驱动的大气环流变化

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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.
机译：在最后一个冰川期，从高纬度到热带地区，北半球气候档案中的主要气候信号是“千禧年代” /“ Oeschger”循环，这是千禧年尺度的大幅度温度振荡。但是，这些突然的气候变化的影响是否扩展到热带和亚热带的南半球（日照的变化被认为是气候的主要直接推动力）尚不清楚。在这里，我们展示了来自巴西亚热带南部的U / Th期石笋的高分辨率氧同位素记录，涵盖了过去116,200年。氧同位素特征随源区的变化和该地区降水量的变化而变化，因此记录了南美的大气环流和对流强度的变化。我们发现，降雨来源和降雨量的这些变化主要是由夏季太阳辐射驱动的，而夏季太阳辐射是由地球的岁差周期控制的。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了热带水文循环，但是在南亚热带巴西，千年尺度的气候变化并不像在北半球那样占主导地位。

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