School of Environmental Sciences, Jawaharlal Nehru University (JNU), New Delhi, 110067, India.
Department of Geology, University of Delhi, Delhi, 110007, India.
Sci Rep. 2020 Sep 18;10(1):15324. doi: 10.1038/s41598-020-71686-4.
Two atmospheric circulation patterns, the Indian Summer Monsoon (ISM) and mid-latitude Westerlies control precipitation and thus glacier variability in the Himalaya. However, the role of the ISM and westerlies in controlling climate and thus past glacier variability in the Himalaya is poorly understood because of the paucity of the ice core records. In this article, we present a new Holocene paleorecord disentangling the presence of the ISM and mid-latitude westerlies and their effect on glacier fluctuations during the Holocene. Our new record is based on high-resolution multi-proxy analyses (δOporewater, deuterium-excess, grain size analysis, permeability, and environmental magnetism) of lake sediments retrieved from Chandratal Lake, Western Himalaya. Our study provides new evidence that improves the current understanding of the forcing factor behind glacier advances and retreat in the Western Himalaya and identifies the 8.2 ka cold event using the aforementioned proxies. The results indicate that the ISM dominated precipitation ~ 21% of the time, whereas the mid-latitude westerlies dominated precipitation ~ 79% of the time during the last 11 ka cal BP. This is the first study that portrays the moisture sources by using the above proxies from the Himalayan region as an alternative of ice core records.
两种大气环流模式，即印度夏季风（ISM）和中纬度西风，控制着喜马拉雅山的降水，从而影响冰川变化。然而，由于冰芯记录的缺乏，ISM 和西风在控制气候以及过去喜马拉雅山冰川变化中的作用仍不清楚。在本文中，我们提出了一个新的全新世古气候记录，用于分离 ISM 和中纬度西风的存在，并研究它们对全新世冰川波动的影响。我们的新记录基于从西喜马拉雅山 Chandratal 湖采集的湖泊沉积物的高分辨率多代分析（δOporewater、氘过剩、粒度分析、渗透率和环境磁学）。我们的研究提供了新的证据，提高了对西喜马拉雅山冰川前进和后退背后的强迫因素的现有认识，并利用上述代理识别了 8.2ka 冷事件。结果表明，在过去的 11000 年 cal BP 中，ISM 主导降水的时间约为 21%，而中纬度西风主导降水的时间约为 79%。这是首次利用来自喜马拉雅地区的上述代理作为冰芯记录的替代物来描绘水汽来源的研究。
