Holocene variation in the Indian Summer Monsoon modulated by the tropical Indian Ocean sea-surface temperature mode
Holocene variation in the Indian Summer Monsoon modulated by the tropical Indian Ocean sea-surface temperature mode
复制标题
热带印度洋海面温度模态调制的印度夏季风全新世变化
DOI：
10.1016/j.catena.2022.106302
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发表时间：
2022
期刊：
影响因子：
6.2
通讯作者：
Yong Wang
中科院分区：
文献类型：
--
作者：
Kai Cui;Yongbo Wang;Xingqi Liu;Ji Shen;Yong Wang
印度夏季风（ISM）的演变由于其对气候和社会经济的重要影响而受到广泛的研究。然而，关于全新世的时间变化及其驱动机制，特别是热带印度洋海表温度（SST）的潜在贡献仍然存在争议。本文对中国西南部北海湿地11.1 kyr的连续沉积记录进行了研究。从沉积条件、流域侵蚀和区域气候变化等方面分析和解释了沉积物的粒度、地球化学元素组成和总有机碳含量。在全新世早期至中期，碎屑输入量增加，水位可能升高，表明在ISM加剧的情况下，流域侵蚀强烈。最大季风强度出现在7.5 ~ 5.2 cal. kyr BP之间，与ISM的各项记录基本一致。我们认为，这种中全新世季风增强主要是由TIO海温异常模态，即印度洋盆地（IOB）模态和印度洋偶极子（IOD）模态触发的。从TIO的全新世海温记录来看，全新世中期可能出现了正海温异常（正IOB模式）和正纬向海温异常梯度（正IOD模式），共同引发了ISM的强化。我们的发现强调了TIO在调制夏季风系统中的重要贡献。TOC含量和中位粒径的突然增加表明，当前的湿地系统是在5.2 cal. kyr BP左右随着区域湿度的下降和ISM的退缩而形成的。此外，在过去800年里，人类活动对流域的影响也很明显，如人类活动引起的森林砍伐导致流域侵蚀加剧。
The evolution of the Indian Summer Monsoon (ISM) has been widely investigated owing to its significant climatic and socioeconomic influences. However, debates remain concerning the temporal variation during the Holocene and its driving mechanisms, particularly the potential contribution of sea-surface temperature (SST) in the tropical Indian Ocean (TIO). Here, we present a continuous sediment record covering the past 11.1 kyrs from the Beihai Wetland, southwestern China. The grain size, geochemical element composition and total organic carbon content (TOC) were analyzed and interpreted in terms of the sedimentary conditions, catchment erosion and regional climate variations. Higher detrital inputs and possibly high water levels were determined during the early to mid-Holocene period, suggesting strong catchment erosion under an intensified ISM. The maximum monsoon intensity appeared between 7.5 and 5.2 cal. kyr BP, which is broadly consistent with various ISM records. We propose that such mid-Holocene monsoon strengthening was primarily triggered by the TIO SST anomaly modes, i.e., the Indian Ocean Basin (IOB) mode and the Indian Ocean dipole (IOD) mode. Based on Holocene SST records from the TIO, a positive SST anomaly (positive IOB mode) and positive zonal SST anomaly gradient (positive IOD mode) may have occurred during the mid-Holocene, which jointly triggered intensification of the ISM. Our findings emphasize the significant contribution of the TIO in modulating the summer monsoon system. The abrupt increases in TOC content and median grain size indicate the formation of the current wetland system at approximately 5.2 cal. kyr BP following the decline in regional moisture as well as the retreat of the ISM. In addition, notable human impacts were determined during the last 800 years, as indicated by intensified catchment erosion in response to human-induced deforestation.