晚第四纪印度洋-太平洋交汇区降水时空演化

SPATIAL AND TEMPORAL PRECIPITATION VARIABILITY IN THE INDO-PACIFIC REGION DURING THE LATE QUATERNARY

印度洋-太平洋交汇区(印太交汇区)作为全球的水汽和热量中心,在多种时间尺度的气候变化中都扮演着重要的角色。然而,迄今该区域晚第四纪古降水时空演化仍不清楚,主要体现在不同区域或不同指标的降水重建结果出现明显不一致、甚至相反的现象。本研究基于印太交汇区已有重建记录,总结了该区域轨道和千年时间尺度上古降水演化特征及机制。在轨道时间尺度上,尽管该区域大多数降水记录都主要受到岁差主控的日射量变化影响,但其响应的相位关系却截然不同,推测是多种气候因子共同作用的结果。在千年时间尺度上,降水变化主要受控于北大西洋千年时间尺度气候突变事件导致的热带辐合带(ITCZ)迁移;其次,厄尔尼诺与南方涛动(ENSO)以及印度洋偶极子(IOD)的活动也对该地区局部降水有所贡献。另外,苏拉威西等印太交汇区中部区域的降水受到海平面变化的显著影响。总体来看,印太交汇区古降水记录仍存在重建指标单一、部分区域缺乏高分辨率记录等问题,降水空间分布及其变化机制也尚不明朗,需更多的高分辨率古降水重建以及模拟工作的开展去全方面阐明印太交汇区降水的时空演化特征及机制。

As a global center of water vapor and heat,the Indo-Pacific region plays an important role in climate change on multiple timescales.However,the spatial and temporal variability of its precipitation during the Late Quaternary is still unclear,as some paleoprecipitation records constructed in different regions or by different proxies are inconsistent and even contradictory.Here,we summarize the characteristics and mechanisms of the precipitation variability on both orbital and millennial timescales based on the proxies in this region.Although most precipitation records are dominated by precession,they respond to different precessional phases,presumably due to the effect of multiple climatic factors such as the meridional migration and/or the expansion/contraction of the Intertropical Convergence Zone(ITCZ) and the phase of El Ni?o and Southern Oscillation-like (ENSO-like) system.In New Guinea,Southwestern Sumatra,and Southeastern Philippines,the precipitation is in phase with austral summer(December) precessional insolation forcing.In Northern Borneo,the precipitation variability corresponds to boreal autumn(October) insolation.All of these reconstructions are consistent with modern records,although some areas are lacking paleoprecipitation reconstructions.On millennial timescales,precipitation variability is mainly controlled by the meridional migration of the ITCZ caused by the North Atlantic abrupt climate events;besides,El Ni?o and Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) also contribute to local precipitation variability.In addition,precipitation in the central Indo-Pacific region is significantly influenced by glacial-interglacial changes,such as the exposure of Sunda and Sahul shelf caused by the sea-level changes,the dry and cold air generated by the Laurentide ice sheet,and changes of the pattern of stationary wave and inter-hemispherical temperature gradients which are also relevant to the ice sheet.Furthermore,in Southern New Guinea,some reconstructions are influenced by obliquity,which might result from the asymmetric continental configuration between Asia and Australia.Overall,problems like undiversified precipitation proxy,lack of high-resolution records,and the unclarity of spatial variability and mechanism of precipitation are yet to be solved.Therefore,more high-resolution paleoprecipitation reconstruction and modelling works are needed to elucidate the spatial and temporal variability of precipitation in the Indo-Pacific region.