张肖剑^1,,
靳立亚^2,3,,,
AndreyGanopolski⁴,
MatteoWilleit⁴
1. 南京大学地理与海洋科学学院, 江苏 南京 210023
2. 成都信息工程大学大气科学学院, 四川 成都 610225
3. 兰州大学资源环境学院, 甘肃 兰州 730000
4. Potsdam Institute for Climate Impact Research, Potsdam 14473, Germany

基金项目: 国家自然科学基金项目(批准号：41690111、41775070和41920104005)资助


详细信息

作者简介: 张肖剑, 男, 33岁, 副研究员, 古气候模拟研究, E-mail:zhangxj@nju.edu.cn

通讯作者: 靳立亚, E-mail:jinly@lzu.edu.cn

中图分类号: P532;P534.62⁺2

收稿日期:2020-07-02
修回日期:2020-09-17
刊出日期:2020-11-30

Orbital variations of the East Asian winter monsoon during the past 3 Ma from a transient simulation

Zhang Xiaojian^1,,
Jin Liya^2,3,,,
Andrey Ganopolski⁴,
Matteo Willeit⁴
1. School of Geography and Ocean Science, Nanjing University, Nanjing 210023, Jiangsu
2. School of Atmospheric Sciences, Chengdu University of Information Technology, Chengdu 610225, Sichuan
3. College of Earth and Environmental Sciences, Lanzhou University, Lanzhou 730000, Gansu
4. Potsdam Institute for Climate Impact Research, Potsdam 14473, Germany


More Information

Corresponding author: Jin Liya,E-mail:jinly@lzu.edu.cn

MSC: P532;P534.62⁺2

--> Received Date: 02 July 2020
Revised Date: 17 September 2020
Publish Date: 30 November 2020


摘要
摘要:轨道尺度东亚冬季风变率对认识第四纪东亚环境演化和北半球冰盖演化具有重要的作用。文章利用德国波茨坦气候影响研究所的中等复杂程度地球系统模式(CLIMBER-2)对过去3 Ma气候和环境的模拟结果，探讨了轨道尺度东亚冬季风演化特征及其变化机制。采用两种指数反映东亚冬季风强度，分别指示中纬度西风强度(EAWMU)和东亚北风强度(EAWMV)。CLIMBER-2较好地模拟出了3 Ma以来地球冰期-间冰期旋回特征，以及第四纪以来全球变冷趋势。东亚冬季风在过去3 Ma以来呈现逐渐增强的趋势，EAWMV和EAWMU分别在约2.6 Ma和约1.5 Ma突然增强。EAWMV(EAWMU)在约2.2 Ma(约1.5 Ma)之前主要以20 ka岁差周期为主导，约2.2~1.0 Ma(约1.5~1.0 Ma)的转型期以41 ka倾角周期和20 ka岁差周期为主导，约1.0 Ma之后则均出现100 ka、41 ka和20 ka这3个轨道周期特征，并以100 ka偏心率周期为主导。在约2.2 Ma(约1.5 Ma)之前，EAWMV(EAWMU)主要受控于太阳辐射的直接强迫作用，北半球冰盖的作用相对较弱，在此之后北半球冰盖起主导作用，太阳辐射的直接强迫作用相对较弱。因此，第四纪东亚冬季风与北半球冰盖存在复杂的耦合关系，当冰盖规模较小时，它们的关系很弱；反之，当冰盖规模较大时，它们的联系加强。
关键词: 第四纪/
东亚冬季风/
冰量/
太阳辐射/
气候模拟

Abstract:The East Asian winter monsoon(EAWM) is an important component of Earth's climate system, which significantly influences climate changes over East Asia. Orbital-scale variability of the EAWM during the Quaternary period is a crucial issue for paleoclimate researches because it significantly affects the geographical environment in Northern China. In addition, the EAWM provides another perspective for the development of Northern Hemisphere ice sheets given the coupling of the EAWM variability and Northern Hemisphere ice volume at orbital timescales. However, their coupling relationship is doubled by many proxy records and climate simulations. This study intends to explore orbital variations of the EAWM during the past 3 Ma and associated physical mechanisms, especially their response to the Northern Hemisphere ice volume, based on transient simulations by the fully coupled Earth system model of intermediate complexity CLIMBER-2. The CLIMBER-2 considers the synchronous interactions among climate system, carbon cycle, and ice sheets, which therefore requires the sole forcing factor:Earth's orbital variations. The CLIMBER-2 simulates well the glacial cycles and global cooling during the Quaternary period, which provides a solid foundation for the simulation of the EAWM. This study uses two EAWM indices to fully describe EAWM variability. The first EAWM index(EAWMU, u-component of EAWM winds) is defined as the mean zonal near-surface wind velocity over East Asia(35°~45°N and 95°~115°E), which reflects the capacity of the EAWM transporting coarse sediment to Chinese Loess Plateau. The second EAWM index(EAWMV, v-component of EAWM winds) is defined as the strength of the northerly winds over East Asia(25°~35°N and 120°~130°E). Simulation results indicate a general intensification of the EAWM during the past 3 Ma, showing a sharp increase around 2.2 Ma(1.5 Ma) for the EAWMV(EAWMU). Simulated EAWMV(EAWMU) was dominated by 20 ka precession cycle before ca. 2.2 Ma(ca. 1.5 Ma), by 41 ka obliquity and 20 ka precession cycles between ca. 2.2~1.0 Ma(ca. 1.5~1.0 Ma). After ca. 1.0 Ma, both the EAWMV and EAWMU show combined 100 ka eccentricity, 41 ka obliquity and 20 ka precession cycles. The shift in paleoclimatic periodicity of modelled EAWM from 20 ka to 100 ka cycles differs with the loess records, which reveal a shift from 41 ka to 100 ka over the mid-Pleistocene transition. The EAWMU is influenced by the meridional contrast of surface pressure at middle latitudes, which is further controlled by the meridional thermal contrast. The EAWMV is controlled by the sea-land thermal contrast. Before ca. 2.2 Ma(ca. 1.5 Ma), the effect of the Northern Hemisphere ice sheet on the sea-land thermal contrast(meridional thermal contrast) was weaker than the direct effect of the insolation due to the relatively small ice sheet. Therefore, the EAWMV(EAWMU) was dominated by 20 ka precession cycle during the corresponding period. Accompanying by the increase of the ice sheet after ca. 2.2 Ma(ca. 1.5 Ma), the effect of the ice sheet on the sea-land thermal contrast(meridional thermal contrast) was stronger than the direct effect of the insolation. Hence, the EAWMV(EAWMU) was dominated by 20 ka precession and 41 ka obliquity cycles between ca. 2.2~1.0 Ma(ca. 1.5~1.0 Ma), and by 100 ka eccentricity cycle after ca. 1.0 Ma. Our simulations indicate that the coupled relationship between the EAWM and Northern Hemisphere ice volume depends on the size of the ice sheets. The sensitivity of the EAWM to the size of the ice sheets is significant different between the EAWMU and EAWMV, which reflects the spatial difference of the EAWM. Our study further suggests that special caution should be taken when exploring the development of Northern Hemisphere ice sheets based on loess records during the Early Pleistocene.
Key words:Quaternary period/
East Asian winter monsoon/
ice volume/
insolation/
paleoclimate simulation



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