scholarly journals The 4.2 ka BP event: multi-proxy records from a closed lake in the northern margin of the East Asian summer monsoon

2018 ◽  
Vol 14 (10) ◽  
pp. 1417-1425 ◽  
Author(s):  
Jule Xiao ◽  
Shengrui Zhang ◽  
Jiawei Fan ◽  
Ruilin Wen ◽  
Dayou Zhai ◽  
...  
Keyword(s):  
Summer Monsoon ◽  
North Atlantic ◽  
Surface Waters ◽  
East Asian Summer Monsoon ◽  
Asian Summer Monsoon ◽  
East Asian ◽  
Mean Annual Precipitation ◽  
Northern Margin ◽  
Proxy Records ◽  
Asian Summer

Abstract. The 4.2 ka BP event has been widely investigated since it was suggested to be a possible cause for the collapse of ancient civilizations. With the growth of proxy records for decades, however, both its nature and its spatial pattern have become controversial. Here we examined multi-proxy data of the grain-size distribution, ostracode assemblage, pollen assemblage, and the pollen-reconstructed mean annual precipitation from a sediment core at Hulun Lake in northeastern Inner Mongolia spanning the period between 5000 and 3000 cal. yr BP to identify the nature and the associated mechanism of the 4.2 ka BP event occurring in the monsoonal region of eastern Asia. Higher sand fraction contents, littoral ostracode abundances, and Chenopodiaceae pollen percentages together with lower mean annual precipitation reveal a significant dry event at the interval of 4210–3840 cal. yr BP that could be a regional manifestation of the 4.2 ka BP event in the northern margin of the East Asian summer monsoon (EASM). We suggest that the drought would be caused by a decline in the intensity of the EASM on millennial-to-centennial scales that could be physically related to persistent cooling of surface waters in the western tropical Pacific and the North Atlantic. The cooling of western tropical Pacific surface waters could reduce moisture production over the source area of the EASM, while the cooling of North Atlantic surface waters could suppress northward migrations of the EASM rain belt, both leading to a weakened EASM and thus decreased rainfall in the northern margin of the EASM.

scholarly journals The 4.2 ka event: multi-proxy records from a closed lake in the northern margin of the East Asian summer monsoon

2018 ◽  
Author(s):  
Jule Xiao ◽  
Shengrui Zhang ◽  
Jiawei Fan ◽  
Ruilin Wen ◽  
Dayou Zhai ◽  
...  
Keyword(s):  
Summer Monsoon ◽  
North Atlantic ◽  
Surface Waters ◽  
East Asian Summer Monsoon ◽  
Asian Summer Monsoon ◽  
East Asian ◽  
Tropical Pacific ◽  
Northern Margin ◽  
Proxy Records ◽  
Asian Summer

Abstract. The 4.2 ka event has been widely investigated since it was suggested to be a possible cause for the collapse of ancient civilizations. With the growth of proxy records for decades, however, both its nature and its spatial pattern have become controversial. Here we examined multi-proxy data of the grain-size distribution, ostracode assemblage, pollen assemblage and the pollen-reconstructed mean annual precipitation from a sediment core at Hulun Lake in northeastern Inner Mongolia spanning the period between 5000 and 3000 cal yr BP to identify the nature and the associated mechanism of the 4.2 ka event occurring in the monsoonal region of eastern Asia. Higher sand fraction contents, littoral ostracodes abundances and Chenopodiaceae pollen percentages together with lower mean annual precipitations reveal a significant dry event at the interval of 4230–3820 cal yr BP that could be a regional manifestation of the 4.2 ka event in the northern margin of the East Asian summer monsoon (EASM). We suggest that the drought would be caused by a large decline in the intensity of the EASM on millennial-to-centennial scales that could be physically related to persistent cooling of surface waters in the western tropical Pacific and the North Atlantic. The cooling of western tropical Pacific surface waters could reduce moisture productions over the source area of the EASM, while the cooling of North Atlantic surface waters could suppress northward migrations of the EASM rainbelt, both leading to a weakened EASM and thus decreased rainfall in the northern margin of the EASM.

scholarly journals Variations in the East Asian summer monsoon over the past millennium and their links to the Tropic Pacific and North Atlantic oceans

2019 ◽  
Author(s):  
Fucai Duan ◽  
Zhenqiu Zhang ◽  
Yi Wang ◽  
Jianshun Chen ◽  
Zebo Liao ◽  
...  
Keyword(s):  
Summer Monsoon ◽  
North Atlantic ◽  
East Asian Summer Monsoon ◽  
Asian Summer Monsoon ◽  
East Asian ◽  
Meridional Overturning Circulation ◽  
Central China ◽  
Ice Age ◽  
Future Global Warming ◽  
Asian Summer

Abstract. Variations of East Asian summer monsoon (EASM) during the last millennium could help enlighten the monsoonal response to future global warming. Here we present a precisely dated and highly resolved stalagmite δ18O record from the Yongxing Cave, central China. Our new record, combined with a previously published one from the same cave, indicates that the EASM has changed dramatically in association with the global temperature rising. In particular, our record shows that the EASM has intensified during the Medieval Climate Anomaly (MCA) and the Current Warm Period (CWP) but weakened during the Little Ice Age (LIA). We find that the EASM intensity is similar during the MCA and CWP periods in both northern and central China, but relatively stronger during the CWP in southern China. This discrepancy indicates a complicated regional response of the EASM to the anthropogenic forcing. The intensified and weakened EASM during the MCA and LIA matches well with the warm and cold phases of Northern Hemisphere surface air temperature, respectively. This EASM pattern also corresponds well with the rainfall over the tropical Indo-Pacific warm pool. Surprisingly, our record shows a strong association with the North Atlantic climate as well. The intensified (weakened) EASM correlates well with positive (negative) phases of North Atlantic Oscillation. In addition, our record links well with the strong (weak) Atlantic meridional overturning circulation during the MCA (LIA) period. All above-mentioned correlations indicate that the EASM tightly couples with oceanic processes in the tropical Pacific and North Atlantic oceans during the MCA and LIA.

scholarly journals The Eurasian ice sheet reinforces the East Asian summer monsoon during the interglacial 500 000 years ago

2008 ◽  
Vol 4 (2) ◽  
pp. 79-90 ◽  
Author(s):  
◽  
A. Berger ◽  
E. Driesschaert ◽  
H. Goosse ◽  
M. F. Loutre ◽  
...  
Keyword(s):  
Summer Monsoon ◽  
East Asian Summer Monsoon ◽  
Asian Summer Monsoon ◽  
East Asian ◽  
Ice Core ◽  
Ice Sheet ◽  
The Tibetan Plateau ◽  
Three Dimension ◽  
Proxy Records ◽  
Asian Summer

Abstract. Deep-sea and ice-core records show that interglacial periods were overall less "warm" before about 420 000 years ago than after, with relatively higher ice volume and lower greenhouse gases concentration. This is particularly the case for the interglacial Marine Isotope Stage 13 which occurred about 500 000 years ago. However, by contrast, the loess and other proxy records from China suggest an exceptionally active East Asian summer monsoon during this interglacial. A three-dimension Earth system Model of Intermediate complexity was used to understand this seeming paradox. The astronomical forcing and the remnant ice sheets present in Eurasia and North America were taken into account in a series of sensitivity experiments. Expectedly, the seasonal contrast is larger and the East Asian summer monsoon is reinforced compared to Pre-Industrial time when Northern Hemisphere summer is at perihelion. Surprisingly, the presence of the Eurasian ice sheet was found to reinforce monsoon, too, through a south-eastwards perturbation planetary wave. The trajectory of this wave is influenced by the Tibetan plateau.

Improvement of Multimodel Ensemble Seasonal Prediction Skills over East Asian Summer Monsoon Region Using a Climate Filter Concept

2013 ◽  
Vol 52 (5) ◽  
pp. 1127-1138 ◽  
Author(s):  
Doo Young Lee ◽  
Joong-Bae Ahn ◽  
Karumuri Ashok
Keyword(s):  
Summer Monsoon ◽  
North Atlantic ◽  
East Asian Summer Monsoon ◽  
Asian Summer Monsoon ◽  
East Asian ◽  
Seasonal Prediction ◽  
Multimodel Ensemble ◽  
Suitable Climate ◽  
Asian Summer ◽  
Summer Monsoon Region

AbstractThe authors propose the use of a “climate filter” concept to enhance prediction skill of a multimodel ensemble (MME) suite for the East Asian summer monsoon (EASM) precipitation and temperature at 850 hPa. The method envisages grading models on the basis of the degree of reproducibility of the association of EASM variability with a few relevant climate drivers with the respective model hindcasts for the period 1981–2003. The analysis identifies the previous winter Niño-3.4 and spring North Atlantic Oscillation indices as the most suitable climate drivers in designing a climate filter for evaluating models that replicate the observed teleconnections to EASM well. The results show that the hindcast skills of a new MME with the better-performing models are significantly higher than those from the nonperforming models or from an all-inclusive operational MME.

scholarly journals Influence of the Summer NAO on the Spring-NAO-Based Predictability of the East Asian Summer Monsoon

2016 ◽  
Vol 55 (7) ◽  
pp. 1459-1476 ◽  
Author(s):  
Fei Zheng ◽  
Jianping Li ◽  
Yanjie Li ◽  
Sen Zhao ◽  
Difei Deng
Keyword(s):  
Summer Monsoon ◽  
North Atlantic ◽  
East Asian Summer Monsoon ◽  
Asian Summer Monsoon ◽  
East Asian ◽  
Dominant Mode ◽  
The North ◽  
Secondary Role ◽  
Asian Summer ◽  
The North Atlantic

AbstractThe dominant mode of atmospheric circulation over the North Atlantic region is the North Atlantic Oscillation (NAO). The boreal spring NAO may imprint its signal on contemporaneous sea surface temperature (SST), leading to a North Atlantic SST tripolar pattern (NAST). This pattern persists into the following summer and modulates the East Asian summer monsoon (EASM). Previous studies have shown that the summer NAST is caused mainly by the preceding spring NAO, whereas the contemporaneous summer NAO plays a secondary role. The results of this study illustrate that, even if the summer NAO plays a secondary role, it may also perturb summer SST anomalies caused by the spring NAO. There are two types of perturbation caused by the summer NAO. If the spring and summer NAO patterns have the same (opposite) polarities, the summer NAST tends to be enhanced (reduced) by the summer NAO, and the correlation between the spring NAO and EASM is usually stronger (weaker). In the former (latter) case, the spring-NAO-based prediction of the EASM tends to have better (limited) skill. These results indicate that it is important to consider the evolution of the NAO when forecasting the EASM, particular when there is a clear reversal in the polarity of the NAO, because it may impair the spring-NAO-based EASM prediction.

scholarly journals Vegetation feedback causes delayed ecosystem response to East Asian Summer Monsoon Rainfall during the Holocene

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jun Cheng ◽  
Haibin Wu ◽  
Zhengyu Liu ◽  
Peng Gu ◽  
Jingjing Wang ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Summer Monsoon ◽  
East Asian Summer Monsoon ◽  
Monsoon Rainfall ◽  
Asian Summer Monsoon ◽  
East Asian ◽  
Northern China ◽  
Tree Cover ◽  
Proxy Records ◽  
Asian Summer

AbstractOne long-standing issue in the paleoclimate records is whether East Asian Summer Monsoon peaked in the early Holocene or mid-Holocene. Here, combining a set of transient earth system model simulations with proxy records, we propose that, over northern China, monsoon rainfall peaked in the early Holocene, while soil moisture and tree cover peaked in the mid-Holocene. The delayed ecosystem (soil moisture and tree cover) response to rainfall is caused by the vegetation response to winter warming and the subsequent feedback with soil moisture. Our study provides a mechanism for reconciling different evolution behaviors of monsoon proxy records; it sheds light on the driving mechanism of the monsoon evolution and monsoon-ecosystem feedback over northern China, with implications to climate changes in other high climate sensitivity regions over the globe.

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