中更新世以来东亚冬季风海陆记录对比  

A COMPARISON OF THE EAST ASIAN WINTER MONSOON RECONSTRUCTIONS FROM TERRESTRIAL AND MARINE SEDIMENTARY RECORDS SINCE THE MID-PLEISTOCENE

作　　者：黄恩清[1] 

机构地区：[1]同济大学海洋地质国家重点实验室,上海200092

出　　处：《第四纪研究》2015年第6期1331-1341,共11页Quaternary Sciences

基　　金：国家自然科学基金项目（批准号：41406054）、中国博士后科学基金项目（批准号：2014M561510）和同济大学海洋地质国家重点实验室自主项目（批准号：biG20130201）共同资助

摘　　要：东亚季风系统是世界上唯一同时具有强劲夏季风和冬季风的气候区.由于东亚冬季风与北半球冰盖体积大小强烈相关,可以提供北半球冰盖在第四纪冰期旋回过程中的变化信息,因此研究东亚冬季风演化具有显著意义.本文通过现代观测数据,发现在多年际时间尺度上,南海南部和北部的年均表层水温差值与南海上空冬季风风速存在相关性.因此,利用南海南北表层水温梯度重建记录,可能可以反演地质历史时期冬季风的强度变化.然而,过去80万年以来,重建的南海表层水温梯度记录与全球冰盖体积、黄土粒度记录不存在相似性.频谱分析结果表明,全球冰盖体积和黄土粒度变化均有偏心率、斜率和岁差周期,且在这些周期上具有显著相关性.南海表层水温差值变化却只有强烈的斜率和岁差周期.斜率周期与全球冰盖体积变化相关,岁差周期与全球冰盖体积和北半球太阳辐射量变化都不存在相关性且没有稳定的相位差.分析表明,认为有两个原因可能引起冬季风海洋记录和黄土记录的差异：一是两类记录分别反映的是低纬度和中纬度的冬季风风速变化,而冬季风在两个区域里的演化历史可能并不一致;二是存在别的因素可能会影响南海的温度梯度变化.冰期时台湾海峡和巽它陆架的出露,会引起南海表层环流的改向,继而导致表层温度场分布的变化.因此,在冰期-间冰期旋回尺度上,南海南北温度梯度不能单纯反映东亚冬季风变化.这两个推测都需要后续高精度海洋数值模拟结果的证实.The East Asian monsoonal zone is the unique climate regime on Earth that has been influenced by both strong summer and winter monsoons. Previous studies have unveiled that the intensity of the East Asian winter monsoon is strongly related to the volume of Northern Hemisphere ice sheets. The evolution of the winter monsoon thus can provide information on the dynamics of Northern Hemisphere ice sheets over the Quaternary glacial-interglacial cycles. Therefore, it becomes crucial to understand the evolution of the winter monsoon history. Based on modern observational data, it has been found that the annual sea surface temperature （SST） gradient between the northern and the southern South China Sea （SCS） is strongly relevant to the winter monsoon wind speed over the SCS on the interannual timescale. Accordingly, the reconstructed north-south SST gradient record may possibly be employed to indicate past changes in the East Asian winter moosoon. The SST gradient record over the past 800ka, however, does not resemble the global ice volume and the loess grain size records. The spectrum analyses results suggest that the global ice volume and the loess grain size are coherent at the eccentricity, obliquity and precession cycles, while the SST gradient record are coherent with the global ice-volume at the obliquity cycle but not at the precession cycle. Moreover, at the precessional period, the SST gradient record does not have a stable phase relationship with the global ice volume or the solar insolation. We infer two possible reasons which could induce the discrepancy between the loess grain-size and the SST gradient records. First, they may reflect winter monsoon variations over the mid-and the low-latitude regimes, respectively, and the winter monsoon history over these two regimes could be different. Second, the SCS SST gradient might have been influence by other factors besides the wind speed of winter monsoon. It is inferred that the exposure of the Sunda Shelf and the Taiwan Strait could have influenced the

关 键 词：东亚冬季风 更新世 南海 黄土 沉积记录 

分 类 号：P722.7[天文地球—海洋科学] P542