scholarly journals Summer precipitation reconstructed quantitatively using a Mid Holocene δ<sup>13</sup>C common millet record from Guanzhong Basin, China

2016 ◽  
Author(s):  
Qing Yang ◽  
Xiaoqiang Li ◽  
Xinying Zhou ◽  
Keliang Zhao ◽  
Nan Sun
Keyword(s):  
Robust Regression ◽  
Asian Summer Monsoon ◽  
Summer Precipitation ◽  
Regression Function ◽  
Growing Season ◽  
Northern China ◽  
Panicum Miliaceum ◽  
Precipitation Record ◽  
Asian Summer ◽  
Guanzhong Basin

Abstract. In order to produce quantitative Holocene precipitation reconstructions for particular geographical areas, explicit proxies and accurate dating controls are required. The fossilized seeds of common millet (Panicum miliaceum) are found throughout the sedimentary strata of northern China, and are highly suited to the production of accurate quantitative Holocene precipitation reconstructions: their isotopic carbon composition (δ13C) gives a measure of the precipitation required during the growing season, and allows these seeds to be dated. We therefore used a robust 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. Our results showed that summer precipitation from 7.7–3.4 ka BP was 240–477 mm, with a mean of 354 mm, i.e. ~ 50 mm or 17 % higher than present levels. Maximal mean summer precipitation peaked at 414 mm, ~ 109 mm (or 36 %) higher than today, occurring during 6.4–5.5 ka BP; this is when the East Asian Summer Monsoon (EASM) was at its peak. As the δ13C-based precipitation record can reliably indicate EASM intensity during the Holocene, this work can provide a reliable proxy for further research into the detailed processes, and precise mechanisms, of the EASM.

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 Anthropogenic forcing of shift in precipitation in Eastern China in late 1970s

2013 ◽  
Vol 13 (5) ◽  
pp. 11997-12032 ◽  
Author(s):  
T. Wang ◽  
H. J. Wang ◽  
O. H. Otterå ◽  
Y. Q. Gao ◽  
L. L. Suo ◽  
...  
Keyword(s):  
East Asian Summer Monsoon ◽  
Yangtze River ◽  
Asian Summer Monsoon ◽  
East Asian ◽  
Eastern China ◽  
Summer Precipitation ◽  
Northern China ◽  
Yangtze River Valley ◽  
Interdecadal Shift ◽  
Asian Summer

Abstract. Observation shows that eastern China has experienced an interdecadal shift in the summer precipitation during the second half of the 20th century. The summer precipitation increased in the middle and lower reaches of the Yangtze River Valley, whereas it decreased in northern China. Here we use a coupled ocean–atmosphere general circulation model and multi-ensemble simulations to show that the interdecadal shift is mainly caused by the combined effect of increasing global greenhouse gases and regional aerosol emissions over China. The rapidly increasing greenhouse gases induce tropical warming and a westward shift of the western Pacific subtropical high, leading to more precipitation in Yangtze River Valley. At the same time the aerosol cooling effect over land contributes to a reduced summer land–sea thermal contrast and therefore to a weakened East Asian summer monsoon and to drought in northern China. Consequently, an anomalous precipitation pattern starts to emerge in eastern China in late 1970s. Our results highlight the important role of anthropogenic forcing agents in shaping the weakened East Asian summer monsoon and associated anomalous precipitation in eastern China.

scholarly journals Relative impact of insolation and Warm Pool surface temperature on the East Asia Summer Monsoon during the MIS-13 interglacial

2014 ◽  
Vol 10 (2) ◽  
pp. 1025-1051 ◽  
Author(s):  
Q. Z. Yin ◽  
U. K. Singh ◽  
A. Berger ◽  
Z. T. Guo ◽  
M. Crucifix
Keyword(s):  
Surface Temperature ◽  
Summer Monsoon ◽  
Climate Modeling ◽  
Southern China ◽  
Asian Summer Monsoon ◽  
Summer Precipitation ◽  
Northern China ◽  
Warm Pool ◽  
Pool Surface ◽  
The Impact

Abstract. During Marine Isotope Stage (MIS) 13, an interglacial about 500 000 years ago, the East Asian summer monsoon (EASM) was suggested exceptionally strong by different proxies in China. However, MIS-13 is a weak interglacial in marine oxygen isotope records and has relatively low CO2 and CH4 concentrations compared to other interglacials of the last 800 000 years. In the mean time, the sea surface temperature (SST) reconstructions show that the Western Pacific Warm Pool was relatively warm during MIS-13. Based on climate modeling experiments, this study aims at investigating whether this Warm Pool warming could explain the exceptionally strong EASM occurring during the relatively cool interglacial MIS-13. The individual contributions of insolation and of the Warm Pool SST as well as their synergism are quantified through experiments with the Hadley Centre atmosphere model, HadAM3 and using the factor separation technique. The SST over the Warm Pool region has been increased based on geological reconstructions. Our results show that the pure impact of a strong summer insolation contributes to strengthen significantly the summer precipitation in northern China but only little in southern China. The pure impact of enhanced Warm Pool SST reduces, slightly, the summer precipitation in both northern and southern China. However, the synergism between insolation and enhanced Warm Pool SST contributes to a large increase of summer precipitation in southern China but to a decrease in northern China. Therefore, the ultimate role of enhanced Warm Pool SST reinforces the impact of insolation in southern China but reduces its impact in northern China. We conclude that enhanced SST over the Warm Pool region does help to explain the strong MIS-13 EASM precipitation in southern China as recorded in proxy data, but other explanation is needed for explaining the exceptionally strong EASM in northern China.

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.

scholarly journals Changes in East Asian summer monsoon precipitation during the Holocene deduced from a freshwater flux reconstruction of the Changjiang (Yangtze River) based on the oxygen isotope mass balance in the northern East China Sea

2015 ◽  
Vol 11 (2) ◽  
pp. 265-281 ◽  
Author(s):  
Y. Kubota ◽  
R. Tada ◽  
K. Kimoto
Keyword(s):  
East Asian Summer Monsoon ◽  
Yangtze River ◽  
Asian Summer Monsoon ◽  
East Asian ◽  
Summer Precipitation ◽  
Freshwater Flux ◽  
The Holocene ◽  
Middle Holocene ◽  
The Past ◽  
Asian Summer

Abstract. The δ18O of seawater (δ18Ow), an indirect indicator of sea surface salinity (SSS), in the northern East China Sea (ECS) is reconstructed for the Holocene using paired analyses of Mg / Ca ratio and δ18O of planktic foraminiferal tests. According to modern observation, interannual variations in SSS during summer in the northern ECS are mainly controlled by the Changjiang (Yangtze River) discharge, which reflects summer rainfall in its drainage basin. Thus, changes in the summer SSS in the northern ECS are interpreted as reflecting variations in the East Asian summer monsoon (EASM) precipitation in the Changjiang Basin. This interpretation is confirmed by a strong relationship between the SSS in the northern ECS and the Changjiang discharge during the wet season (May–October) based on instrumental salinity records from 1951 to 2000. However, it is difficult to estimate absolute salinity values in the past with high accuracy, because the past salinity–δ18Ow regression slope, end member salinity, and δ18Ow values are not well understood. Here, we conduct δ18Ow mass-balance calculation to estimate the freshwater contribution to the surface water of the northern ECS during the last 7 kyr by assuming a simple mixing between two end members – the seawater and the Changjiang freshwater. The result indicates that there has been no gradual decreasing secular trend in the Changjiang freshwater flux from the middle Holocene to the present day, suggesting that summer insolation in the Northern Hemisphere does not regulate the EASM precipitation in the Changjiang Basin. Instead, internal feedback appears to have been more important during the Holocene. The absence of a decreasing trend in regional summer precipitation over the Changjiang Basin since the middle Holocene is contradictory to Chinese speleothems' δ18O records, suggesting that it is not possible to explain orbital changes in Chinese speleothems' δ18O during the Holocene by changes in summer precipitation, but that such changes are related to other factors such as changes in the moisture source.

scholarly journals A 241-Year Cryptomeria fortune Tree-Ring Chronology in Humid Subtropical China and Its Linkages with the Pacific Decadal Oscillation

Atmosphere ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 247
Author(s):  
Zhipeng Dong ◽  
Dai Chen ◽  
Jianhua Du ◽  
Guang Yang ◽  
Maowei Bai ◽  
...  
Keyword(s):  
Tree Ring ◽  
Tree Rings ◽  
Pacific Decadal Oscillation ◽  
Asian Summer Monsoon ◽  
Growing Season ◽  
Subtropical China ◽  
Tree Ring Chronology ◽  
The Pacific ◽  
The World ◽  
Asian Summer

Humid subtropical China is an “oasis” relative to other dry subtropics of the world due to the prevailing of the East Asian summer monsoon (EASM). Although many long climate sensitive tree-rings have been published to understand the historical climate change over various regions in China, long tree-ring chronologies in humid subtropical China are rare due to the difficulty to find old growth trees. This study established a tree-ring chronology spanning from 1776 to 2016 from Cryptomeria fortunei Hooibrenk ex Otto et Dietr in Liancheng area of humid subtropical China, which is also currently the longest chronology in Fujian province. Similar to the climate-growth relationships in neighboring regions, our tree-ring chronology is limited by cold temperature in winter and spring and drought in summer. In addition, a drought stress before the growing season also played a role in limiting the growth of our tree rings. Our climate sensitive tree rings showed different correlations with the Pacific Decadal Oscillation (PDO) in different periods, possibly via modulation of the EASM.

scholarly journals Anthropogenic agent implicated as a prime driver of shift in precipitation in eastern China in the late 1970s

2013 ◽  
Vol 13 (24) ◽  
pp. 12433-12450 ◽  
Author(s):  
T. Wang ◽  
H. J. Wang ◽  
O. H. Otterå ◽  
Y. Q. Gao ◽  
L. L. Suo ◽  
...  
Keyword(s):  
Indian Ocean ◽  
20Th Century ◽  
Yangtze River ◽  
East Asian ◽  
Eastern China ◽  
Summer Precipitation ◽  
Northern China ◽  
Yangtze River Valley ◽  
Interdecadal Shift ◽  
Asian Summer

Abstract. Observation shows that eastern China experienced an interdecadal shift in the summer precipitation during the second half of the 20th century. The summer precipitation increased in the middle and lower reaches of the Yangtze River valley, whereas it decreased in northern China. Here we use a coupled ocean–atmosphere general circulation model and multi-ensemble simulations to show that the interdecadal shift is mainly caused by the anthropogenic forcing. The rapidly increasing greenhouse gases induce a notable Indian Ocean warming, causing a westward shift of the western Pacific subtropical high (WPSH) and a southward displacement of the East Asia westerly jet (EAJ) on an interdecadal timescale, leading to more precipitation in Yangtze River valley. At the same time the surface cooling effects from the stronger convection, higher precipitation and rapidly increasing anthropogenic aerosols contribute to a reduced summer land–sea thermal contrast. Due to the changes in the WPSH, the EAJ and the land–sea thermal contrast, the East Asian summer monsoon weakened resulting in drought in northern China. Consequently, an anomalous precipitation pattern started to emerge over eastern China in the late 1970s. According to the model, the natural forcing played an opposite role in regulating the changes in WPSH and EAJ, and postponed the anthropogenically forced climate changes in eastern China. The Indian Ocean sea surface temperature is crucial to the response, and acts as a bridge to link the external forcings and East Asian summer climate together on a decadal and longer timescales. Our results further highlight the dominant roles of anthropogenic forcing agents in shaping interdecadal changes of the East Asian climate during the second half of the 20th century.

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