Asian Monsoon Failure and Megadrought During the Last Millennium

Science ◽  
2010 ◽  
Vol 328 (5977) ◽  
pp. 486-489 ◽  
Author(s):  
E. R. Cook ◽  
K. J. Anchukaitis ◽  
B. M. Buckley ◽  
R. D. D'Arrigo ◽  
G. C. Jacoby ◽  
...  
Keyword(s):  
Asian Monsoon ◽  
Last Millennium ◽  
Monsoon Failure

Sensitivity of a coupled climate-carbon cycle model to large volcanic eruptions during the last millennium

Tellus B ◽  
2010 ◽  
Vol 62 (5) ◽  
Author(s):  
Victor Brovkin ◽  
Stephan J. Lorenz ◽  
Johann Jungclaus ◽  
Thomas Raddatz ◽  
Claudia Timmreck ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Volcanic Eruptions ◽  
Last Millennium ◽  
Cycle Model ◽  
Carbon Cycle Model ◽  
Large Volcanic Eruptions

scholarly journals Linking Holocene East Asian monsoon variability to solar forcing and ENSO activity: Multi-proxy evidence from a peatland in Northeastern China

The Holocene ◽  
2021 ◽  
pp. 095968362199466
Author(s):  
Nannan Li ◽  
Arash Sharifi ◽  
Frank M Chambers ◽  
Yong Ge ◽  
Nathalie Dubois ◽  
...  
Keyword(s):  
Asian Monsoon ◽  
East Asian Monsoon ◽  
Asian Summer Monsoon ◽  
East Asian ◽  
Northeastern China ◽  
Solar Irradiation ◽  
Enso Events ◽  
Monsoon Area ◽  
Wavelet Coherency ◽  
Cross Wavelet

High-resolution proxy-based paleoenvironmental records derived from peatlands provide important insights into climate changes over centennial to millennial timescales. In this study, we present a composite climatic index (CCI) for the Hani peatland from northeastern China, based on an innovative combination of pollen-spore, phytolith, and grain size data. We use the CCI to reconstruct variations of the East Asian summer monsoon (EASM) intensity during the Holocene. This is accomplished with complete ensemble empirical mode decomposition (CEEMD), REDFIT, and cross-wavelet coherency analysis to reveal the periodicities (frequencies) of the multi-proxy derived CCI sequences and to assess potential external forcing of the EASM. The results showed that periodicities of ca. 300–350, 475, 600, 1075, and 1875 years were present in the Hani CCI sequence. Those periodicities are consistent with previously published periodicities in East Asia, indicating they are a product of external climate controls over an extensive region, rather than random variations caused by peatland-specific factors. Cross-wavelet coherency analysis between the decomposed CCI components and past solar activity reconstructions suggests that variations of solar irradiation are most likely responsible for the cyclic characteristics at 500-year frequency. We propose a conceptual model to interpret how the sun regulates the monsoon climate via coupling with oceanic and atmospheric circulations. It seems that slight solar irradiation changes can be amplified by coupling with ENSO events, which result in a significant impact on the regional climate in the East Asian monsoon area.

scholarly journals Changes in Paleovegetation and Paleoclimate in China Since the Late Middle Pleistocene: A Case Study of the Dajiuhu Basin

2021 ◽  
Vol 13 (9) ◽  
pp. 4848
Author(s):  
Liwei Wu ◽  
Xinling Li ◽  
Qinghai Xu ◽  
Manyue Li ◽  
Qiufeng Zheng ◽  
...  
Keyword(s):  
Grain Size ◽  
Asian Monsoon ◽  
East Asian Monsoon ◽  
Asian Summer Monsoon ◽  
East Asian ◽  
Central China ◽  
Middle Pleistocene ◽  
Pollen Record ◽  
The Difference ◽  
Late Middle Pleistocene

The East Asian monsoon system is an important part of global atmospheric circulation; however, records of the East Asian monsoon from different regions exhibit different evolutionary rhythms. Here, we show a high-resolution record of grain size and pollen data from a lacustrine sediment core of Dajiuhu Lake in Shennongjia, Hubei Province, China, in order to reconstruct the paleovegetation and paleoeclimate evolution of the Dajiuhu Basin since the late Middle Pleistocene (~237.9 ka to the present). The results show that grain size and pollen record of the core DJH-2 are consistent with the δ18O record of stalagmites from Sanbao Cave in the same area, which is closely related to the changes of insolation at the precessional (~20-kyr) scale in the Northern Hemisphere. This is different from the records of the Asian summer monsoon recorded in the Loess Plateau of North China, which exhibited dominant 100-kyr change cyclicities. We suggest that the difference between paleoclimatic records from North and South China is closely related to the east–west-oriented mountain ranges of the Qinling Mountains in central China that blocked weakened East Asia summer monsoons across the mountains during glacial periods.

scholarly journals Understanding the variability of the rainfall dipole in West Africa using the EC-Earth last millennium simulation

2021 ◽  
Author(s):  
Qiong Zhang ◽  
Ellen Berntell ◽  
Qiang Li ◽  
Fredrik Charpentier Ljungqvist
Keyword(s):  
West Africa ◽  
Model Simulation ◽  
Rainfall Variability ◽  
Low Pressure ◽  
Last Millennium ◽  
Tropical Atlantic ◽  
Gulf Of Guinea ◽  
Dipole Pattern ◽  
Sahel Region ◽  
Heat Low

AbstractThere is a well-known mode of rainfall variability associating opposite hydrological conditions over the Sahel region and the Gulf of Guinea, forming a dipole pattern. Previous meteorological observations show that the dipole pattern varies at interannual timescales. Using an EC-Earth climate model simulation for last millennium (850–1850 CE), we investigate the rainfall variability in West Africa over longer timescales. The 1000-year-long simulation data show that this rainfall dipole presents at decadal to multidecadal and centennial variability and long-term trend. Using the singular value decomposition (SVD) analysis, we identified that the rainfall dipole present in the first SVD mode with 60% explained variance and associated with the variabilities in tropical Atlantic sea surface temperature (SST). The second SVD mode shows a monopole rainfall variability pattern centred over the Sahel, associated with the extra-tropical Atlantic SST variability. We conclude that the rainfall dipole-like pattern is a natural variability mode originated from the local ocean–atmosphere-land coupling in the tropical Atlantic basin. The warm SST anomalies in the equatorial Atlantic Ocean favour an anomalous low pressure at the tropics. This low pressure weakens the meridional pressure gradient between the Saharan Heat Low and the tropical Atlantic. It leads to anomalous northeasterly, reduces the southwesterly moisture flux into the Sahel and confines the Gulf of Guinea's moisture convergence. The influence from extra-tropical climate variability, such as Atlantic multidecadal oscillation, tends to modify the rainfall dipole pattern to a monopole pattern from the Gulf of Guinea to Sahara through influencing the Sahara heat low. External forcing—such as orbital forcing, solar radiation, volcanic and land-use—can amplify/dampen the dipole mode through thermal forcing and atmosphere dynamical feedback.

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