scholarly journals The East Asian Monsoon During MIS 2 Expressed in a Speleothem δ18O Record From Jintanwan Cave, Hunan, China

2010 ◽  
Vol 73 (3) ◽  
pp. 541-549 ◽  
Author(s):  
Jason Cosford ◽  
Hairuo Qing ◽  
Yin Lin ◽  
Bruce Eglington ◽  
Dave Mattey ◽  
...  
Keyword(s):  
Summer Monsoon ◽  
East Asian Summer Monsoon ◽  
Asian Monsoon ◽  
East Asian Monsoon ◽  
Asian Summer Monsoon ◽  
East Asian ◽  
Climatic Changes ◽  
Decadal Scale ◽  
Socotra Island ◽  
Asian Summer

Stalagmite J1 from Jintanwan Cave, Hunan, China, provides a precisely dated, decadally resolved δ18O proxy record of paleoclimatic changes associated with the East Asian monsoon from ∽29.5 to 14.7 ka and from ∽12.9 to 11.0 ka. At the time of the last glacial maximum (LGM), the East Asian summer monsoon weakened and then strengthened in response to changes in Northern Hemisphere insolation. As the ice sheets retreated the East Asian summer monsoon weakened, especially during Heinrich event H1, when atmospheric and oceanic teleconnections transferred the climatic changes around the North Atlantic to the monsoonal regions of Eastern Asia. A depositional hiatus between ∽14.7 and 12.9 ka leaves the deglacial record incomplete, but an abrupt shift in δ18O values at ∽11.5 ka marks the end of the Younger Dryas and the transition into the Holocene. Comparisons of the J1 record to other Chinese speleothem records indicate synchronous climatic changes throughout monsoonal China. Further comparisons to a speleothem record from western Asia (Socotra Island) and to Greenland ice cores support hemispherical-scale paleoclimatic change. Spectral and wavelet analyses reveal centennial- and decadal-scale periodicities that correspond to solar frequencies and to oscillations in atmospheric and oceanic circulation.

scholarly journals Three exceptionally strong East-Asian summer monsoon events during glacial conditions in the past 470 kyr

2008 ◽  
Vol 4 (6) ◽  
pp. 1289-1317 ◽  
Author(s):  
D.-D. Rousseau ◽  
N. Wu ◽  
Y. Pei ◽  
F. Li
Keyword(s):  
Summer Monsoon ◽  
Asian Monsoon ◽  
East Asian Monsoon ◽  
Asian Summer Monsoon ◽  
East Asian ◽  
Precipitation Regime ◽  
The Past ◽  
Ecological Requirements ◽  
Asian Summer ◽  
The Tropics

Abstract. Chinese loess sequences are interpreted as a reliable record of the past variation of the East Asian monsoon regime through the alternation of loess and paleosols units, dominated by the winter and summer monsoon, respectively. Different proxies have been used to describe this system, mostly geophysical, geochemical or sedimentological. Terrestrial mollusks are also a reliable proxy of past environmental conditions and are often preserved in large numbers in loess deposits. The analysis of the mollusk remains in the Luochuan sequence, comprising L5 loess to S0 soil, i.e. the last 500 ka, shows that for almost all identified species, the abundance is higher at the base of the interval (L5 to L4) than in the younger deposits. Using the present ecological requirements of the identified mollusk species in the Luochuan sequence allows the definition of two main mollusk groups varying during the last 500 kyr. The cold-aridiphilous individuals indicate the so-called Asian winter monsoon regime and predominantly occur during glacials, when dust is deposited. The thermal-humidiphilous mollusks are prevalent during interglacial or interstadial conditions of the Asian summer monsoon, when soil formation takes place. In the sequence, three events with exceptionally high abundance of the Asian summer monsoon indicators are recorded during the L5, L4 and L2 glacial intervals, i.e., at about 470, 360 and 170 kyr, respectively. The L5 and L4 events appear to be the strongest (high counts). Similar variations have also been identified in the Xifeng sequence, distant enough from Luochuan, but also in Lake Baikal further North, to suggest that this phenomenon is regional rather than local. The indicators of the summer monsoon within the glacial intervals imply a strengthened East-Asian monsoon interpreted as corresponding to marine isotope stages 6, 10 and 12, respectively. The L5 and L2 summer monsoons are coeval with Mediterranean sapropels S12 and S6, which characterize a strong African summer monsoon with relatively low surface water salinity in the Indian Ocean. Changes in the precipitation regime could correspond to a response to a particular astronomical configuration (low obliquity, low precession, summer solstice at perihelion) leading to an increased summer insolation gradient between the tropics and the high latitudes and resulting in enhanced atmospheric water transport from the tropics to the African and Asian continents. However, other climate drivers such as reorganization of marine and atmospheric circulations, tectonic, and the extent of the Northern Hemisphere ice sheet are also discussed.

A late Holocene molecular hydrogen isotope record of the East Asian Summer Monsoon in Southwest Japan

2016 ◽  
Vol 86 (3) ◽  
pp. 287-294 ◽  
Author(s):  
Els E. van Soelen ◽  
Naohiko Ohkouchi ◽  
Hisami Suga ◽  
Jaap S. Sinninghe Damsté ◽  
Gert-Jan Reichart
Keyword(s):  
Summer Monsoon ◽  
East Asian Summer Monsoon ◽  
Molecular Hydrogen ◽  
Hydrogen Isotope ◽  
East Asian Monsoon ◽  
Asian Summer Monsoon ◽  
East Asian ◽  
Ice Age ◽  
Southwest Japan ◽  
Asian Summer

AbstractPrecipitation in Japan is strongly affected by the East Asian monsoon system, resulting in wet summer conditions and relatively dry winter conditions. Few paleo-monsoon records exist from northeastern Asia, especially records showing decadal- to centennial-scale variability. Here we present a molecular hydrogen isotope (δD) record from Lake Kaiike, a small coastal lake in southwest Japan, to provide insight into monsoonal precipitation over the past two millennia. The δD record of friedelin, a terrestrial higher plant lipid, reveals three major shifts in precipitation: a decline from >-185‰ to <-190‰ at 1700 cal yr BP suggests a change to wetter conditions; values between -187.5‰ and -180‰ from 1480 to 800 cal yr BP indicate reduced precipitation; and a decline to below -195‰ after 800 cal yr BP reflects moist conditions during the Little Ice Age. These results highlight variability in the intensity of the East Asian Summer Monsoon occurring on decadal to centennial time scales. El Niño-like conditions are likely responsible for periods of high monsoon intensity, but comparison with other records in the region (northeast China and Japan) shows that contradicting patterns also exist, and so explaining these rainfall patterns is not straightforward.

Timing and duration of the East Asian summer monsoon maximum during the Holocene based on stalagmite data from North China

The Holocene ◽  
2018 ◽  
Vol 28 (10) ◽  
pp. 1631-1641 ◽  
Author(s):  
Na Zhang ◽  
Yan Yang ◽  
Hai Cheng ◽  
Jingyao Zhao ◽  
Xunlin Yang ◽  
...  
Keyword(s):  
Northern Hemisphere ◽  
Summer Monsoon ◽  
East Asian Summer Monsoon ◽  
Late Holocene ◽  
East Asian Monsoon ◽  
Asian Summer Monsoon ◽  
East Asian ◽  
Early Holocene ◽  
Humidity Change ◽  
Asian Summer

We present a continuous C-O isotope series that shows the detailed variability of East Asian summer monsoon (EASM) since 11.0 ka BP. The series is based on two stalagmites, namely, DSY1 and LM2, which were, respectively, obtained from Dongshiya and Laomu caves. The δ18O profiles of stalagmite excurse negatively in early Holocene and gradually become positive after around 6.9 ka BP, tracking the change in Northern Hemisphere summer insolation. Moreover, the ‘early-Holocene maximum’ supported by stalagmite δ18O records differs from the ‘mid-Holocene maximum’ indicated by geological archives, such as lake sediments and loess. This difference may be caused by different definition indicators of monsoon intensity. Stalagmite δ18O is relative to EASM intensity, but irrelative to precipitation in the East Asian monsoon region. The time intervals of EASM maximum and Holocene climatic optimum are desynchronized, which is confirmed by the variation in the stalagmite δ13C series. Stalagmite δ13C and δ18O have different variation tendencies. The tendency of δ13C in early mid-Holocene was generally light, but it was discontinuity and disrupted by rapid positive shift between 8.2 and 7.7 ka BP. We conclude that a rapid shift of about 8 ka BP is a turning point, before and after which δ13 C acquires different controlling factors. Stalagmite δ13 C showed no signs of positive excurse in late Holocene but it exhibited another characteristic, namely, millennial time scale oscillations. The few changes in stalagmite δ13 C is attributed to weakened insolation during summer in the northern hemisphere, which leads to low evaporation rate, thereby modulating effective humidity change. The edge of the seasonal monsoonal front in northern China during monsoon recession is sensitive to the rain belt and causes the δ13 C of the stalagmite to fluctuate greatly. This phenomenon shows that the climate in the study area is unstable in the late Holocene

A reconstruction of the East Asian summer monsoon index over the half past millennium

2020 ◽  
Author(s):  
Feng Shi ◽  
Hugues Goosse ◽  
Jianping Li ◽  
Fredrik Charpentier Ljungqvist ◽  
Sen Zhao ◽  
...  
Keyword(s):  
Summer Monsoon ◽  
East Asian Summer Monsoon ◽  
Yangtze River ◽  
East Asian Monsoon ◽  
Asian Summer Monsoon ◽  
East Asian ◽  
Eastern China ◽  
Lower Troposphere ◽  
The Yangtze River ◽  
Asian Summer

&lt;p&gt;The EASM largely determines variations in summer precipitation in the East Asian monsoon region where approximately one-quarter of the world&amp;#8217;s population live. A reliable East Asian summer monsoon (EASM) index covering several centuries is important in order to understand EASM dynamics. The wind-field is frequently used to calculate the EASM index during the instrumental period. However, available climate proxy data rather respond to direct precipitation changes. A gridded extended summer (May&amp;#8211;September, MJJAS) precipitation reconstruction for China covering AD 1470&amp;#8211;2000 is used to indirectly reconstruct two types of EASM indices (defined by the strength of the 850hPa southwesterly winds and a north-south gradient of the zonal winds), using the negative correlation between the EASM index and summer (June&amp;#8211;August, JJA) rainfall in the middle and lower reaches of the Yangtze River of China. The two EASM indices are validated by independent historical documentary data for eastern China. The physical processes ruling the EASM variability are explored, highlighting a baroclinic structure over the middle and lower reaches of the Yangtze River. It includes an&amp;#160;anticyclonic&amp;#160;circulation accompanied by high pressure anomalies&amp;#160;in&amp;#160;the lower troposphere and a cyclonic circulation with low pressure anomaly in the upper&amp;#160;troposphere. This is associated with a decrease in atmospheric water vapor content (due to divergence), which will decrease summer rainfall in the region, and contribute to the strengthen of the EASM variability. The dominated and inter-annual component of the EASM variation is possibly linked to the &amp;#8216;ENSO-like&amp;#8217; sea surface temperature according to a data assimilation experiment performed with the Community Earth System Model-Last Millennium Ensemble (CESM-LME) simulation.&lt;/p&gt;

scholarly journals Three exceptionally strong East-Asian summer monsoon events during glacial times in the past 470 kyr

2009 ◽  
Vol 5 (2) ◽  
pp. 157-169 ◽  
Author(s):  
D.-D. Rousseau ◽  
N. Wu ◽  
Y. Pei ◽  
F. Li
Keyword(s):  
Summer Monsoon ◽  
Asian Monsoon ◽  
East Asian Monsoon ◽  
Asian Summer Monsoon ◽  
East Asian ◽  
Precipitation Regime ◽  
The Past ◽  
Ecological Requirements ◽  
Asian Summer ◽  
The Tropics

Abstract. Chinese loess sequences are interpreted as a reliable record of the past variation of the East Asian monsoon regime through the alternation of loess and paleosols units, dominated by the winter and summer monsoon, respectively. Different proxies have been used to describe this system, mostly geophysical, geochemical or sedimentological. Terrestrial mollusks are also a reliable proxy of past environmental conditions and are often preserved in large numbers in loess deposits. The analysis of the mollusk remains in the Luochuan sequence, comprising L5 loess to S0 soil, i.e. the last 500 ka, shows that for almost all identified species, the abundance is higher at the base of the interval (L5 to L4) than in the younger deposits. Using the present ecological requirements of the identified mollusk species in the Luochuan sequence allows the definition of two main mollusk groups varying during the last 500 kyr. The cold-aridiphilous individuals indicate the so-called Asian winter monsoon regime and predominantly occur during glacials, when dust is deposited. The thermal-humidiphilous mollusks are prevalent during interglacial or interstadial conditions of the Asian summer monsoon, when soil formation takes place. In the sequence, three events with exceptionally high abundance of the Asian summer monsoon indicators are recorded during the L5, L4 and L2 glacial intervals, i.e., at about 470, 360 and 170 kyr, respectively. The L5 and L4 events appear to be the strongest (high counts). Similar variations have also been identified in the Xifeng sequence, distant enough from Luochuan, but also in Lake Baikal further North, to suggest that this phenomenon is regional rather than local. The indicators of the summer monsoon within the glacial intervals imply a strengthened East-Asian monsoon interpreted as corresponding to marine isotope stages 12, 10 and 6, respectively. The L5 and L2 summer monsoons are coeval with Mediterranean sapropels S12 and S6, which characterize a strong African summer monsoon with relatively low surface water salinity in the Indian Ocean. Changes in the precipitation regime could correspond to a response to a particular astronomical configuration (low obliquity, low precession, summer solstice at perihelion) leading to an increased summer insolation gradient between the tropics and the high latitudes and resulting in enhanced atmospheric water transport from the tropics to the African and Asian continents. However, other climate drivers such as reorganization of marine and atmospheric circulations, tectonic, and the extent of the Northern Hemisphere ice sheet are also discussed.

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

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

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

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

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

2012 ◽  
Vol 25 (20) ◽  
pp. 6975-6988 ◽  
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.

scholarly journals 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

2016 ◽  
Vol 29 (13) ◽  
pp. 5027-5040 ◽  
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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