Indian summer monsoon variability during the holocene as recorded in sediments of the Arabian Sea: Timing and implications
Indian summer monsoon variability during the holocene as recorded in sediments of the Arabian Sea: Timing and implications
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DOI：
10.1007/s10872-007-0084-8
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发表时间：
2007-12
影响因子：
2.3
通讯作者：
M. Thamban;H. Kawahata;V. Rao
中科院分区：
文献类型：
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作者：
M. Thamban;H. Kawahata;V. Rao
印度季风降水在全新世有显著的波动，可靠地重建这些事件的发生时间及其意义，对于我们理解低纬气候系统对强迫因子的影响和响应是非常有益的。我们已经进行了高分辨率的陆源代理研究，从阿拉伯海东部边缘的氧气最低区的层压沉积物芯重建夏季季风控制的降水变化在全新世。在这个核心的陆源代理指标的时间变化，结合其他高品质的核心从阿拉伯海，建议在整个全新世季风降水的几个突然事件。全新世早期季风的增强在9500年和9100年BP发生在两个突然的步骤，并在8500年BP开始逐渐减弱。在距今7000年前记录的降水减弱，与印度的类似条件同步。在我们的研究中记录的最重要的弱季风期之一是在6000和5500年BP之间。降水记录的频谱分析显示，在2200年，1350年，950年，750年，470年，320年，220年，156年，126年，113年，104年和92年的统计显着的周期性。这些千年至百年的周期大多存在于各种季风记录以及树木年轮Δ 14 C数据和/或其他太阳代理记录中。我们认为，在整个全新世，外部，太阳活动的小变化在很大程度上控制了印度季风，而内部，非太阳的原因可能会影响振幅的十年到百年振荡。
Indian monsoon precipitation fluctuated significantly during the Holocene and a reliable reconstruction of the timing of the events and their implications is of great benefit to our understanding of the effect and response of low latitude climate systems to the forcing factors. We have carried out high-resolution terrigenous proxy studies on a laminated sediment core from the Oxygen Minimum Zone of the eastern Arabian Sea margin to reconstruct the summer monsoon-controlled precipitation changes during the Holocene. The temporal variation in the terrigenous proxy indicators of this core, in combination with other high-quality cores from the Arabian Sea, suggests several abrupt events in monsoon precipitation throughout the Holocene. The early Holocene monsoon intensification occurred in two abrupt steps at 9500 and 9100 years BP and weakened gradually thereafter, starting at 8500 years BP. A weakening in precipitation recorded at ∼7000 years BP, synchronous with similar conditions in India. One of the most significant weak monsoon periods recorded in our studies lies between 6000 and 5500 years BP. Spectral analysis of the precipitation records reveals statistically significant periodicities at 2200, 1350, 950, 750, 470, 320, 220, 156, 126, 113, 104 and 92 years. Most of these millennial-to-centennial cycles exist in various monsoon records as well as the tree ring Δ14C data and/or other solar proxy records. We suggest that throughout the Holocene, externally, small changes in solar activity controlled the Indian monsoon to a large extent, whereas internally, non-solar causes could have influenced the amplitude of decadal-to-centennial oscillations.