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南半球中纬度西风带的迁移控制着南大洋深层水通风,从而驱动大气CO2浓度的变化和全球气候变化.作为西风带直接控制的锋面,亚热带锋面(STF)的移动反映了西风带的迁移.通过南塔斯曼海西部ODP1170站位高分辨率的底栖有孔虫氧同位素(δ18OB)地层和海水表层温度(SST),及其他站位温度记录和南极冰芯中古气候参数的综合研究,重建了800ka以来STF的迁移历史,以及其与南大洋通风性、冰盖体积大小和大气CO2浓度之间的关系.南塔斯曼海域800ka以来的SST平均值为10.2℃,低于该海域现代年均SST(12℃).但MIS1的平均SST最高,达到11.6℃,而MIS4的平均SST最低,为7.8℃.最高SST出现在MIS5,为14.7℃;最低的SST出现在MIS2,为6.2℃.在冰期-间冰期旋回中,STF相对于其现代的位置,向南或北迁移超过3个纬度.在最暖的MIS5,STF可能向南迁移到49°S以南;在最冷的MIS2,STF可能向北迁移到43°S以北.在轨道周期上,西风带的迁移领先于冰盖体积大小变化,但与南极大气温度同步变化.当太阳辐射同时影响南极大气和南大洋表层海水温度时,南大洋SST变化导致STF和西风带迁移.而STF和西风带的迁移又控制南大洋环流和深层水通风,从而驱动大气CO2浓度变化.冰盖体积变化只是大气CO2浓度变化的积极反馈,而不是独立的驱动力.
The migration of mid-latitude westerlies in the southern hemisphere controls the deep water aeration in the Southern Ocean to drive changes in atmospheric CO2 concentration and global climate change. As the direct frontier in the westerlies, the movement of the subtropical front (STF) reflects the westerlies migration High-resolution Benthic Foraminiferal Oxygen Isotope (δ18OB) Formation and Seawater Surface Temperature (SST) in the ODP Site 1170 West of the South Tasman Sea and Other Station Temperature Records and Paleoclimate Parameters in the Antarctic Ice Core were reconstructed for 800 ka The history of STF migration and its relationship with the Southern Ocean’s aeration, ice sheet volume and atmospheric CO2 concentration.The average SST value since the beginning of 800 ka in the South Tasman Sea is 10.2 ℃, lower than the average annual SST (12) ℃), but the average SST of MIS1 is the highest, reaching 11.6 ℃, while the average SST of MIS4 is the lowest at 7.8 ℃. The highest SST appears at MIS5 at 14.7 ℃ and the lowest SST appears at MIS2 at 6.2 ℃. In glacial cycles, the STF migrates more than three latitudes south or north relative to its modern location, and at the warmest MIS5, the STF may migrate south to 49 ° S south; in coldest MIS2, the STF may move north Migration to north of 43 ° S. During orbital period On the upper and the westerlies, the migration of the Westerly Belt leads the change of the volume of the ice sheet, but changes with the temperature of the Antarctic at the same time.When the solar radiation affects both the Antarctic atmosphere and the surface seawater temperature in the Southern Ocean, the SST changes in the Southern Ocean lead to the migration of the STF and the westerlies. And the shifting of the westerlies in turn control the circulation of the Southern Ocean and deep-water ventilation to drive the change of atmospheric CO2 concentration.The change of ice sheet volume is only a positive feedback rather than an independent driving force for the change of atmospheric CO2 concentration.