日本海中部60ka以来的风尘沉积对西风环流演化的指示

发布时间：2018-11-01 12:39

【摘要】：对位于西风环流下风区日本海中部LV53-23岩芯沉积物的粒度特征进行了研究,重建了日本海末次冰期(~60 ka)以来的西风环流演化历史和空间变化规律.结果显示,岩芯沉积物以粉砂为主且粒度频率分布曲线多呈单峰分布,与现代日本黄沙和前人报道的邻近区域的岩芯粒度特征一致,具有典型的风尘沉积特征.众数粒组-粉砂组分的中值粒径分析表明,粉砂组分中值粒径可以用作岩芯沉积反映西风环流的替代性指标.在亚轨道及千年尺度上,粉砂组分中值粒径在MIS 3期的冰阶-间冰阶千年尺度旋回与西风环流密切相关:冰阶时,粉砂组分中值粒径增大,这与西风急流轴较长时间位于青藏高原南部,西风环流影响范围变大,风速增强,能携带更多近源的蒙古戈壁-中国东北沙地风尘至日本海有关;间冰阶时,粉砂组分中值粒径减小,这是由于西风急流轴位于青藏高原北部,携带更多远源的塔克拉玛干沙漠风尘至日本海.而在轨道尺度上,末次盛冰期时粉砂组分中值粒径的稳定低值与北半球65°N日照辐射量良好对应,表明北半球日照辐射量和中高纬温度梯度差对西风环流远距离输运粉尘起到重要作用,盛冰期时西风急流轴受北半球冰盖扩张影响显著南移导致西风环流范围也随之南移,从而对日本海40°~50°N上空西风影响减弱.
[Abstract]:The grain size characteristics of LV53-23 core sediments in the central part of the Sea of Japan are studied in the westerly circulation downwind region, and the evolution history and spatial variation of the westerly circulation since the last glacial period (~ 60 ka) in the Sea of Japan have been reconstructed. The results show that the core sediments are mainly silt and the distribution curves of grain size frequency are single-peak, which is consistent with the core granularity characteristics of Huangsha in modern Japan and the adjacent areas reported by predecessors, and has the typical characteristics of aeolian dust deposition. The analysis of the median particle size of the module- silt component shows that the median particle size of the silt component can be used as an alternative index for core deposition to reflect the westerly circulation. On the suborbital and millennium scales, the millennial cycle of the median particle size of silt components in MIS _ 3 is closely related to the westerly circulation: the median particle size of silt component increases during the ice terrace. This is related to the westerly jet axis located in the south of the Qinghai-Tibet Plateau for a long time, the westerly circulation becomes larger, the wind speed increases, and it can carry more near-source wind dust from Mongolia Gobi to the Sea of Japan. The median particle size of silt component decreases during the interglacial terrace because the westerly jet axis lies in the northern part of the Qinghai-Xizang Plateau and carries more wind dust from the Taklimakan Desert to the Sea of Japan. On the orbital scale, the stable low value of the median particle size of silt during the last glacial peak corresponds well to the radiation of 65 掳N sunshine in the Northern Hemisphere. The results show that the solar radiation and the temperature gradient at middle and high latitudes play an important role in the long-range transport of dust in the westerly circulation, and the westerly jet axis moved southward during the maximum ice age due to the significant southward movement of the westerly jet axis under the influence of the expansion of the Northern Hemisphere ice sheet. Thus, the influence on the westerly wind over 40 掳~ 50 掳N of the Sea of Japan is weakened.
【作者单位】：南京大学海岸与海岛开发教育部重点实验室;国家海洋局第一海洋研究所海洋沉积与环境地质国家海洋局重点实验室;青岛海洋科学与技术国家实验室海洋地质过程与环境功能实验室;V.I.Il’ichev
【基金】：“全球变化与海气相互作用”专项(GASI-GEOGE-03) 国家重点研发计划(2016YFA0601903) 国家自然科学基金(U1606401,41420104005) 泰山学者工程专项资助
【分类号】：P512.2;P532

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