Carbon and nitrogen signatures of sedimentary organic matter from Dali Lake in Inner Mongolia: Implications for Holocene hydrological and ecological variations in the East Asian summer monsoon margin

AbstractA sediment core from Hulun Lake, Inner Mongolia was analyzed for species assemblages and shell chemistry of ostracodes to investigate changes in the hydrology and climate of the East Asian summer monsoon margin during the Holocene. Darwinula stevensoni was abundant, Ilyocypris spp. scarce, littoral ostracodes absent and Mg/Ca, Sr/Ca and δ18O were low 11,100 to 8300 yr ago, indicating high lake levels and cool/fresh waters. Darwinula stevensoni declined largely, Ilyocypris spp. throve, littoral ostracodes were rare and chemical indicators remained in low values 8300 to 6200 yr ago, suggesting that the lake continued high stands but water became warm. The lake then contracted and water became cool/brackish 6200 to 4300 yr ago. Littoral ostracodes flourished 4300 to 3350 yr ago, marking the lowest lake levels of the entire Holocene. The lake level recovered and water salinity decreased 3350 to 1900 yr ago. From 1900 to 500 yr ago, the lake maintained the preceding status albeit lowered stands and increased salinities 1100 to 800 yr ago. During the recent 500 yr, the lake expanded and water salinity decreased. The data imply that the East Asian summer monsoon did not intensify until 8300 yr ago and weakened dramatically 4300 to 3350 yr ago.

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Millennial- and centennial-scale droughts at the northern margin of the East Asian summer monsoon during the last deglaciation: Sedimentological evidence from Dali Lake

Palaeogeography Palaeoclimatology Palaeoecology ◽

10.1016/j.palaeo.2018.11.001 ◽

2019 ◽

Vol 514 ◽

pp. 361-372 ◽

Cited By ~ 4

Author(s):

Jiawei Fan ◽

Jule Xiao ◽

Xiaoguang Qin

Keyword(s):

Summer Monsoon ◽

East Asian Summer Monsoon ◽

Asian Summer Monsoon ◽

East Asian ◽

Last Deglaciation ◽

Northern Margin ◽

Dali Lake ◽

Asian Summer ◽

The Last Deglaciation

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Efficient transport of atmospheric microplastics onto the continent via the East Asian summer monsoon

Journal of Hazardous Materials ◽

10.1016/j.jhazmat.2021.125477 ◽

2021 ◽

Vol 414 ◽

pp. 125477

Author(s):

Xiaohui Wang ◽

Kai Liu ◽

Lixin Zhu ◽

Changjun Li ◽

Zhangyu Song ◽

...

Keyword(s):

Summer Monsoon ◽

East Asian Summer Monsoon ◽

Asian Summer Monsoon ◽

East Asian ◽

Asian Summer ◽

Efficient Transport

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Holocene variability of East Asian summer monsoon as viewed from the speleothem δ18O records in central China

Earth and Planetary Science Letters ◽

10.1016/j.epsl.2021.116758 ◽

2021 ◽

Vol 558 ◽

pp. 116758

Author(s):

Yanjun Cai ◽

Xing Cheng ◽

Le Ma ◽

Ruixue Mao ◽

Sebastian F.M. Breitenbach ◽

...

Keyword(s):

Summer Monsoon ◽

East Asian Summer Monsoon ◽

Asian Summer Monsoon ◽

East Asian ◽

Central China ◽

Asian Summer

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Nonlinear, Intraseasonal Phases of the East Asian Summer Monsoon: Extraction and Analysis Using Self-Organizing Maps

Journal of Climate ◽

10.1175/jcli-d-11-00512.1 ◽

2012 ◽

Vol 25 (20) ◽

pp. 6975-6988 ◽

Cited By ~ 40

Author(s):

Jung-Eun Chu ◽

Saji N. Hameed ◽

Kyung-Ja Ha

Keyword(s):

Time Scales ◽

Summer Monsoon ◽

East Asian Summer Monsoon ◽

Asian Summer Monsoon ◽

East Asian ◽

Self Organizing Maps ◽

Dry Spell ◽

Asian Summer ◽

Upper Level ◽

Self Organizing

Abstract The hypothesis that regional characteristics of the East Asian summer monsoon (EASM) result from the presence of nonlinear coupled features that modulate the seasonal circulation and rainfall at the intraseasonal time scale is advanced in this study. To examine this hypothesis, the authors undertake the analysis of daily EASM variability using a nonlinear multivariate data classifying algorithm known as self-organizing mapping (SOM). On the basis of various SOM node analyses, four major intraseasonal phases of the EASM are identified. The first node describes a circulation state corresponding to weak tropical and subtropical pressure systems, strong upper-level jets, weakened monsoonal winds, and cyclonic upper-level vorticity. This mode, related to large rainfall anomalies in southeast China and southern Japan, is identified as the mei-yu–baiu phase. The second node represents a distinct circulation state corresponding to a strengthened subtropical high, monsoonal winds, and anticyclonic upper-level vorticity in southeast Korea, which is identified as the changma phase. The third node is related to copious rain over Korea following changma, which we name the postchangma phase. The fourth node is situated diagonally opposite the changma mode. Because Korea experiences a dry spell associated with this SOM node, it is referred to as the dry-spell phase. The authors also demonstrate that a strong modulation of the changma and dry-spell phases on interannual time scales occurs during El Niño and La Niña years. Results imply that the key to predictability of the EASM on interannual time scales may lie with analysis and exploitation of its nonlinear characteristics.

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The Variability of the Indian–East Asian Summer Monsoon Interface in Relation to the Spring Seesaw Mode between the Indian Ocean and the Central-Western Pacific

Journal of Climate ◽

10.1175/jcli-d-15-0839.1 ◽

2016 ◽

Vol 29 (13) ◽

pp. 5027-5040 ◽

Cited By ~ 7

Author(s):

Jie Cao ◽

Shu Gui ◽

Qin Su ◽

Yali Yang

Keyword(s):

Indian Ocean ◽

Summer Monsoon ◽

East Asian Summer Monsoon ◽

General Circulation ◽

Asian Summer Monsoon ◽

East Asian ◽

Western Pacific ◽

Observational Analysis ◽

Westerly Winds ◽

Asian Summer

Abstract The interannual zonal movement of the interface between the Indian summer monsoon and the East Asian summer monsoon (IIE), associated with the spring sea surface temperature (SST) seesaw mode (SSTSM) over the tropical Indian Ocean (TIO) and the tropical central-western Pacific (TCWP), is studied for the period 1979–2008. The observational analysis is based on Twentieth Century Reanalysis data (version 2) of atmospheric circulations, Extended Reconstructed SST data (version 3), and the Climate Prediction Center Merged Analysis of Precipitation. The results indicate that the IIE’s zonal movement is significantly and persistently correlated with the TIO–TCWP SSTSM, from spring to summer. The results of two case studies resemble those obtained by regression analysis. Experiments using an atmospheric general circulation model (ECHAM6) substantiate the key physical processes revealed in the observational analysis. When warmer (colder) SSTs appear in the TIO and colder (warmer) SSTs occur in the TCWP, the positive (negative) SSTSM forces anomalous easterly (westerly) winds over the Bay of Bengal (BOB), South China Sea (SCS), and western North Pacific (WNP). The anomalous easterly (westerly) winds further result in a weakened (strengthened) southwest summer monsoon over the BOB and a strengthened (weakened) southeast summer monsoon over the SCS and WNP. This causes the IIE to shift farther eastward (westward) than normal.

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