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首页> 外文期刊>Journal of Geophysical Research. Biogeosciences >Enhancement of dust source area during past glacial periods due to changes of the Hadley circulation
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Enhancement of dust source area during past glacial periods due to changes of the Hadley circulation

机译：由于哈德利环流的变化，过去冰川期的尘埃源面积增加了

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Tropical deserts (e.g., Sahara, Arabian desert, Australian desert) are located within the Hadley circulation. Most of the dust uplifted from these deserts is carried by trade winds and deposited in tropical oceans with very little, if any, transported to polar regions. During glacial periods the dust concentrations in polar ice cores were a factor of 10 to 100 higher than during interglacial periods, including the current Holocene. The early general circulation model simulations of the past glacial climate were not able to reproduce these high mineral dust concentrations; the most recent attempts achieve an increased dust transport to polar regions by extending dust source areas to higher latitudes. We present a hypothesis that during glacial periods the Hadley cell is confined closer to the equator. This contraction of the Hadley circulation leads to the geographical change of the boundary between the tropical and the midlatitude circulation regimes. During the glacial periods a considerable fraction of the current tropical deserts was located outside the region of the Hadley circulation. This allowed the dust to be uplifted and transported by midlatitude storm systems to the polar regions. We present a model for the contraction of the Hadley circulation during the past glacial periods based on the Schneider-Lindzen and Held-Hou model of symmetric tropical circulation and on the assumption that the tropical sea surface temperatures were lower during glacial periods than they are today. [References: 45]
机译：热带沙漠（例如撒哈拉沙漠，阿拉伯沙漠，澳大利亚沙漠）位于哈德利环流内。从这些沙漠升起的大部分灰尘是由顺风携带的，并沉积在热带海洋中，很少（如果有的话）被运送到极地地区。在冰川期，极地冰芯中的尘埃浓度比包括当前全新世在内的冰川期高出10到100倍。过去冰川气候的早期一般循环模型模拟无法再现这些高矿物尘浓度。最近的尝试是通过将粉尘源区域扩展到更高的纬度来增加粉尘向极地的传输。我们提出一个假说，在冰河时期，哈德利单元被限制在更靠近赤道的位置。哈德利环流的这种收缩导致热带和中纬度环流体系之间边界的地理变化。在冰川期，当前热带沙漠的相当一部分位于哈德利环流区域之外。这使尘埃被中纬度风暴系统提升并运送到极地地区。我们基于对称热带环流的Schneider-Lindzen和Held-Hou模型，并假设冰川期的热带海表温度比今天低，提出了过去冰川期Hadley环流的收缩模型。 。 [参考：45]

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