Grass habitat analysis and phytolith-based quantitative reconstruction of Asian monsoon climate change in the sand-loess transitional zone, northern China

2019 ◽  
Vol 92 (2) ◽  
pp. 519-529 ◽  
Author(s):  
Hanlin Wang ◽  
Huayu Lu ◽  
Hongyan Zhang ◽  
Shuangwen Yi ◽  
Yao Gu ◽  
...  
Keyword(s):  
Asian Monsoon ◽  
Asian Summer Monsoon ◽  
Regional Scale ◽  
Northern China ◽  
Transitional Zone ◽  
Mean Annual Temperature ◽  
Quantitative Reconstruction ◽  
Climate Parameters ◽  
Habitat Analysis ◽  
Asian Summer

AbstractWe investigated climate niches of grasses at regional scales and quantitatively reconstruct Asian monsoon precipitation at the sand-loess transitional zone in northern China. Our results provide direct evidence that certain grass lineages have been specialized in specific habitats: Pooideae grasses stand out and occupy a much cooler environment than all other subfamilies; Pooideae, Aristidoideae, and Chloridoieae occupy dry environments. Pooideae grasses occupy the coldest and driest environments compared to all other subfamilies, with a mean annual temperature (MAT) and precipitation (MAP) of ~13.6 to ~15.3°C and 224 to ~1674 mm, respectively, at a regional scale. We built a database for grasses and their corresponding climate parameters. Based on this database, past climate parameters at the margin of the Asian summer monsoon since ~70 ka were quantitatively reconstructed by phytolith assemblages. They show that this area was dominated by cold- and dry-adapted grasses since ~70 ka with a MAT and MAP of ~3.3 to ~11.0 °C and ~442 to ~900 mm, respectively, generally consistent with the results of phytolith-based transfer function reconstructions and with the results of previous nearby pollen-based quantitative reconstructions. With the improvement of the species-climate and ecosystem dataset, our database-based method is a promising quantitative reconstruction approach to past climatic change in the monsoon region.

scholarly journals Quantitative reconstruction of summer precipitation using a mid-Holocene <i>δ</i><sup>13</sup>C common millet record from Guanzhong Basin, northern China

2016 ◽  
Vol 12 (12) ◽  
pp. 2229-2240 ◽  
Author(s):  
Qing Yang ◽  
Xiaoqiang Li ◽  
Xinying Zhou ◽  
Keliang Zhao ◽  
Nan Sun
Keyword(s):  
Asian Summer Monsoon ◽  
Summer Precipitation ◽  
Regression Function ◽  
Growing Season ◽  
Northern China ◽  
Panicum Miliaceum ◽  
Quantitative Reconstruction ◽  
Asian Summer ◽  
Guanzhong Basin ◽  
Early Human

Abstract. To quantitatively reconstruct Holocene precipitation for particular geographical areas, suitable proxies and faithful dating controls are required. The fossilized seeds of common millet (Panicum miliaceum) are found throughout the sedimentary strata of northern China and are suited to the production of quantitative Holocene precipitation reconstructions: their isotopic carbon composition (δ13C) gives a measure of the precipitation required during the growing season of summer (here the interval from mid-June to September) and allows these seeds to be dated. We therefore used a regression function, as part of a systematic study of the δ13C of common millet, to produce a quantitative reconstruction of mid-Holocene summer precipitation in the Guanzhong Basin (107°40′–107°49′ E, 33°39′–34°45′ N). Our results showed that mean summer precipitation at 7.7–3.4 ka BP was 353 mm,  ∼  50 mm or 17 % higher than present levels, and the variability increased, especially after 5.2 ka BP. Maximum mean summer precipitation peaked at 414 mm during the period 6.1–5.5 ka BP,  ∼  109 mm (or 36 %) higher than today, indicating that the East Asian summer monsoon (EASM) peaked at this time. This work can provide a new proxy for further research into continuous paleoprecipitation sequences and the variability of summer precipitation, which will promote the further research into the relation between early human activity and environmental change.

scholarly journals Direct radiative effects of dust aerosols emitted from the Tibetan Plateau on the East Asian summer monsoon – a regional climate model simulation

2017 ◽  
Author(s):  
Hui Sun ◽  
Xiaodong Liu ◽  
Zaitao Pan
Keyword(s):  
Tibetan Plateau ◽  
Regional Climate Model ◽  
East Asian Summer Monsoon ◽  
Asian Monsoon ◽  
Climate Model ◽  
Asian Summer Monsoon ◽  
Regional Climate ◽  
East Asian ◽  
Dust Aerosols ◽  
Asian Summer

Abstract. While dust aerosols emitted from major Asian sources such as Taklimakan and Gobi Deserts have been shown to have strong effect on Asian monsoon and climate, the role of dust emitted from Tibetan Plateau (TP) itself, where aerosols can directly interact with the TP heat pump because of their physical proximity both in location and elevation, has not been examined. This study uses the dust coupled RegCM4.1 regional climate model to simulate the spatiotemporal distribution of dust aerosols originating in the TP and their radiative effects on the East Asian summer monsoon (EASM) during both heavy and light dust years. Two 20-year simulations with and without the dust emission from TP showed that direct radiative cooling in the mid-troposphere induced by the TP locally produced dust aerosols resulted in an overall anticyclonic circulation anomaly in the low-troposphere centered over the TP region. The northeasterly anomaly in the EASM region reduces its strength considerably. The simulations found a significant negative correlation between the TP column dust load produced by local emissions and the corresponding anomaly in the EASM index (R=−0.41). The locally generated TP dust can cause surface cooling far downstream in eastern Mongolia and northeastern China through stationery Rossby wave propagation. Although contribution to the total Asian dust source from within TP (mainly Qaidam Basin) is relatively small, its impacts on Asian monsoon and climate seems disproportionately large, likely owning to its higher elevation within TP itself.

scholarly journals Delivery of halogenated very short-lived substances from the West Indian Ocean to the stratosphere during Asian summer monsoon

2017 ◽  
Author(s):  
Alina Fiehn ◽  
Birgit Quack ◽  
Helmke Hepach ◽  
Steffen Fuhlbrügge ◽  
Susann Tegtmeier ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Interannual Variability ◽  
Summer Monsoon ◽  
Asian Monsoon ◽  
Asian Summer Monsoon ◽  
Source Region ◽  
West Indian ◽  
The West ◽  
West Indian Ocean ◽  
Asian Summer

Abstract. Halogenated very short-lived substances (VSLS) are naturally produced in the ocean and emitted to the atmosphere. When transported to the stratosphere, these compounds can have a significant influence on the ozone layer and climate. During a research cruise on RV Sonne in the subtropical and tropical West Indian Ocean in July and August 2014, we measured the VSLS, methyl iodide (CH3I) and for the first time bromoform (CHBr3) and dibromomethane (CH2Br2), in surface seawater and the marine atmosphere to derive their emission strengths. Using the Lagrangian transport model Flexpart with ERA-Interim meteorological fields, we calculated the direct contribution of observed VSLS emissions to the stratospheric halogen burden during Asian summer monsoon. Furthermore, we compare the in situ calculations with the interannual variability of transport from a larger area of the West Indian Ocean surface to the stratosphere for July 2000–2015. We found that the West Indian Ocean is a strong source region for CHBr3 (910 pmol m−2 h−1), very strong for CH2Br2 (930 pmol m−2 h−1), and average for CH3I (460 pmol m−2 h−1). The atmospheric transport from the tropical West Indian Ocean surface to the stratosphere experiences two main pathways. On very short timescales, especially relevant for the shortest-lived compound CH3I (3.5 days lifetime), convection above the Indian Ocean lifts oceanic air masses and VSLS towards the tropopause. On a longer timescale, the Asian summer monsoon circulation transports oceanic VSLS towards India and Bay of Bengal, where they are lifted with the monsoon convection and reach stratospheric levels in the southeastern part of the Asian monsoon anticyclone. This transport pathway is more important for the longer-lived brominated compounds (17 and 150 days lifetime for CHBr3 and CH2Br2). The entrainment of CHBr3 and CH3I from the West Indian Ocean to the stratosphere during Asian summer monsoon is less than from previous cruises in the tropical West Pacific Ocean during boreal autumn/early winter, but higher than from the tropical Atlantic during boreal summer. In contrast, the projected CH2Br2 entrainment was very high because of the high emissions during the West Indian Ocean cruise. The 16-year July time series shows highest interannual variability for the short-lived CH3I and lowest for the long-lived CH2Br2. During this time period, a small increase of VSLS entrainment from the West Indian Ocean through the Asian monsoon to the stratosphere is found. Overall, this study confirms that the subtropical and tropical West Indian Ocean is an important source region of halogenated VSLS, especially CH2Br2, to the troposphere and stratosphere during the Asian summer monsoon.

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.

Differentiated roles of mean climate and climate stability on post-glacial birch distributions in northern China

The Holocene ◽  
2019 ◽  
Vol 29 (11) ◽  
pp. 1758-1766
Author(s):  
Hao Qian ◽  
Liu Hongyan ◽  
Yang Shilei ◽  
Yang Weihua ◽  
Song Zhaoliang
Keyword(s):  
Asian Summer Monsoon ◽  
Northern China ◽  
Distribution Range ◽  
Early Holocene ◽  
Distribution Models ◽  
Study Region ◽  
Climate Conditions ◽  
Climate Stability ◽  
Asian Summer ◽  
Mean Climate

Past changes in the distribution of tree species are critical to predict future vegetation dynamics under changing climate conditions. In this study, pollen-based reconstruction with 60 pollen records from mid-latitude region was performed in China. Betula emerged after the Last Glacial Maximum (LGM), when the climate ameliorated gradually. The distribution range was small but increased significantly during the early Holocene. However, when the climate was wet and warm during the mid-Holocene, the distribution range did not continue to expand. The relationships between the percentages of Betula pollen and the strength of the East Asian summer monsoon (EASM) or its variability were positively correlated, while those of Betula and Pinus had opposite trends in the study region. Besides, the post-glacial distribution dynamics of Betula platyphylla and Betula dahurica were influenced by climate change which were simulated by species distribution models (SDMs). We conclude that birch distribution in mid-latitudinal northern China was mainly driven by the EASM or its variability, especially during the LGM and early Holocene when the climate was unstable, while the replacement by Pinus and Quercus occurred during the mid-Holocene when the climate remained stable. The future unstable climate may benefit birch development.

A strengthened East Asian Summer Monsoon during Pliocene warmth: Evidence from ‘red clay’ sediments at Pianguan, northern China

2018 ◽  
Vol 155 ◽  
pp. 124-133 ◽  
Author(s):  
Shiling Yang ◽  
Zhongli Ding ◽  
Shaohua Feng ◽  
Wenying Jiang ◽  
Xiaofang Huang ◽  
...  
Keyword(s):  
Summer Monsoon ◽  
East Asian Summer Monsoon ◽  
Asian Summer Monsoon ◽  
East Asian ◽  
Northern China ◽  
Red Clay ◽  
Asian Summer

scholarly journals Long-term decrease in Asian monsoon rainfall and abrupt climate change events over the past 6,700 years

2021 ◽  
Vol 118 (30) ◽  
pp. e2102007118
Author(s):  
Bao Yang ◽  
Chun Qin ◽  
Achim Bräuning ◽  
Timothy J. Osborn ◽  
Valerie Trouet ◽  
...  
Keyword(s):  
Asian Summer Monsoon ◽  
Low Frequency ◽  
Northern China ◽  
Human Migration ◽  
The Tibetan Plateau ◽  
Drying Trend ◽  
Asian Summer ◽  
Second Millennium Bce ◽  
Instrumental Period

Asian summer monsoon (ASM) variability and its long-term ecological and societal impacts extending back to Neolithic times are poorly understood due to a lack of high-resolution climate proxy data. Here, we present a precisely dated and well-calibrated tree-ring stable isotope chronology from the Tibetan Plateau with 1- to 5-y resolution that reflects high- to low-frequency ASM variability from 4680 BCE to 2011 CE. Superimposed on a persistent drying trend since the mid-Holocene, a rapid decrease in moisture availability between ∼2000 and ∼1500 BCE caused a dry hydroclimatic regime from ∼1675 to ∼1185 BCE, with mean precipitation estimated at 42 ± 4% and 5 ± 2% lower than during the mid-Holocene and the instrumental period, respectively. This second-millennium–BCE megadrought marks the mid-to late Holocene transition, during which regional forests declined and enhanced aeolian activity affected northern Chinese ecosystems. We argue that this abrupt aridification starting ∼2000 BCE contributed to the shift of Neolithic cultures in northern China and likely triggered human migration and societal transformation.

scholarly journals Impact of the Asian monsoon on the extratropical lower stratosphere: trace gas observations during TACTS over Europe 2012

2015 ◽  
Vol 15 (23) ◽  
pp. 34765-34812
Author(s):  
S. Müller ◽  
P. Hoor ◽  
H. Bozem ◽  
E. Gute ◽  
B. Vogel ◽  
...  
Keyword(s):  
Asian Monsoon ◽  
Lower Stratosphere ◽  
Asian Summer Monsoon ◽  
Trace Gas ◽  
Boreal Summer ◽  
Monsoon Circulation ◽  
Transport Pathway ◽  
Air Masses ◽  
Time Period ◽  
Asian Summer

Abstract. The transport of air masses originating from the Asian monsoon anticyclone into the extratropical upper troposphere and lower stratosphere (Ex-UTLS) above potential temperatures Θ = 380 K was identified during the HALO aircraft mission TACTS in August and September 2012. In-situ measurements of CO, O3 and N2O during TACTS Flight 2 on the 30 August 2012 show the irreversible mixing of aged with younger (originating from the troposphere) stratospheric air masses within the Ex-UTLS. Backward trajectories calculated with the trajetory module of the CLaMS model indicate that these tropospherically affected air masses originate from the Asian monsoon anticyclone. From the monsoon circulation region these air masses are quasi-isentropically transported above Θ = 380 K into the Ex-UTLS where they subsequently mix with stratospheric air masses. The overall trace gas distribution measured during TACTS shows that this transport pathway has a significant impact on the Ex-UTLS during boreal summer and autumn. This leads to an intensification of the tropospheric influence on the Ex-UTLS with ΔΘ > 30 K (relative to the tropopause) within three weeks during the TACTS mission. In the same time period a weakening of the tropospheric influence on the lowermost stratosphere (LMS) is determined. Therefore, the study shows that the transport of air masses originating from the Asian summer monsoon region within the lower stratosphere above Θ = 380 K is of major importance for the change of the chemical composition of the Ex-UTLS from summer to autumn.

The Annual Cycle, Intraseasonal Oscillations, and Roadblock to Seasonal Predictability of the Asian Summer Monsoon

2006 ◽  
Vol 19 (20) ◽  
pp. 5078-5099 ◽  
Author(s):  
B. N. Goswami ◽  
Guoxiong Wu ◽  
T. Yasunari
Keyword(s):  
Empirical Evidence ◽  
Summer Monsoon ◽  
Annual Cycle ◽  
Asian Monsoon ◽  
Southern Oscillation ◽  
Asian Summer Monsoon ◽  
Internal Variability ◽  
Systematic Bias ◽  
Intraseasonal Oscillations ◽  
Asian Summer

Abstract Factors responsible for limited predictability of the Asian summer monsoon (ASM) are investigated within a conceptual framework for predictability. Predictability of the seasonal mean depends on the interannual variability (IAV) of the monsoon annual cycle (MAC) and is determined by relative contribution of the predictable “external” component of IAV compared to the unpredictable “internal” IAV. Contributions of slow processes such as those involving air–sea interactions associated with the El Niño–Southern Oscillation (ENSO) or local warm ocean–atmosphere interactions in generating IAV of the MAC are reviewed. Empirical evidence that these air–sea interactions modulate the MAC is presented. Estimates of internal IAV have been made from observations as well as atmospheric model simulations. In contrast to a large part of the Tropics where the summer climate is predictable, with the internal variability being much smaller than the external one, the limited predictability of the Asian monsoon appears to be due to the fact that the contribution from the external IAV over the region is relatively weak and comparable to that from internal IAV. Cause for large internal IAV over the ASM region is investigated, and it is proposed that the internal IAV of the MAC is primarily due to interaction between the MAC and the summer intraseasonal oscillations (ISOs). Two mechanisms through which ISOs lead to internal IAV of the MAC are unraveled. The seasonal bias of the ISO anomalies can influence the seasonal mean if the spatial structure of the ISO has significant projection on that of the seasonal mean and if frequency of occurrence of positive and negative phases is unequal. Evidence supporting this is presented. In addition, it is demonstrated that the chaotic summer ISOs modulated by the annually varying forcing associated with the “slow annual cycle” can lead to IAV of the seasonal mean. Empirical evidence that IAV of ISO activity is related to IAV of the seasonal mean or MAC is also presented. Thus, the Asian monsoon would remain a difficult system to predict. To exploit the predictable signal, however, it is imperative that systematic bias of the models is improved and the space–time structure of the summer ISOs is simulated accurately.

Multi-scale Holocene Asian monsoon variability deduced from a twin-stalagmite record in southwestern China

2016 ◽  
Vol 86 (1) ◽  
pp. 34-44 ◽  
Author(s):  
Wei Huang ◽  
Yongjin Wang ◽  
Hai Cheng ◽  
Richard Lawrence Edwards ◽  
Chuan-Chou Shen ◽  
...  
Keyword(s):  
North Atlantic ◽  
Asian Monsoon ◽  
Asian Summer Monsoon ◽  
High Sensitivity ◽  
Southwestern China ◽  
Multi Scale ◽  
Monsoon Variability ◽  
Decadal Scale ◽  
Optimum Period ◽  
Asian Summer

AbstractWe present two isotopic (δ18O and δ13C) sequences of a twin-stalagmite from Zhuliuping Cave, southwestern China, with 230Th dates from 14.6 to 4.6 ka. The stalagmite δ18O record characterizes orbital- to decadal-scale variability of Asian summer monsoon (ASM) intensity, with the Holocene optimum period (HOP) between 9.8 and 6.8 ka BP which is reinforced by its co-varying δ13C data. The large multi-decadal scale amplitude of the cave δ18O indicates its high sensitivity to climate change. Four centennial-scale weak ASM events during the early Holocene are centered at 11.2, 10.8, 9.1 and 8.2 ka. They can be correlated to cold periods in the northern high latitudes, possibly resulting from rapid dynamics of atmospheric circulation associated with North Atlantic cooling. The 8.2 ka event has an amplitude more than two-thirds that of the Younger Dryas (YD), and is significantly stronger than other cave records in the Asia monsoon region, likely indicating a more severe dry climate condition at the cave site. At the end of the YD event, the δ13C record lags the δ18O record by 300–500 yr, suggesting a multi-centennial slow response of vegetation and soil processes to monsoon enhancement.

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