scholarly journals Long-term fire activity under the East Asian monsoon responding to spring insolation, vegetation type, global climate, and human impact inferred from charcoal records in Lake Biwa sediments in central Japan

2018 ◽  
Vol 179 ◽  
pp. 59-68 ◽  
Author(s):  
Jun Inoue ◽  
Chikako Okuyama ◽  
Keiji Takemura
Keyword(s):  
Human Impact ◽  
Asian Monsoon ◽  
Lake Biwa ◽  
East Asian Monsoon ◽  
Vegetation Type ◽  
Global Climate ◽  
East Asian ◽  
Central Japan ◽  
Fire Activity

scholarly journals Water pH and temperature in Lake Biwa from MBT'/CBT indices during the last 282 000 years

2014 ◽  
Vol 10 (2) ◽  
pp. 1153-1178
Author(s):  
T. Ajioka ◽  
M. Yamamoto ◽  
K. Takemura ◽  
A. Hayashida
Keyword(s):  
Air Temperature ◽  
Lake Biwa ◽  
East Asian Monsoon ◽  
Asian Summer Monsoon ◽  
East Asian ◽  
Summer Precipitation ◽  
Central Japan ◽  
Temperature And Precipitation ◽  
Monsoon Variability ◽  
Water Ph

Abstract. We generated a 282 000-year record of water pH and temperature in Lake Biwa, central Japan, by analysing the methylation index (MBT') and cyclisation ratio (CBT) of branched tetraethers in sediments from piston and borehole cores to understand the responses of precipitation and air temperature in central Japan to the East Asian monsoon variability on the orbital timescale. Because water pH in Lake Biwa is determined by phosphorus input driven by precipitation, the record of water pH should indicate changes in summer precipitation in central Japan. The estimated pH showed significant periodicity at 19 and 23 ka (precession) and at 41 ka (obliquity). The variation in the estimated pH agrees with variation in the pollen temperature index. This indicates synchronous variation in summer air temperature and precipitation in central Japan, which contradicts the conclusions of previous studies. The variation in estimated pH was also synchronous with the variation of oxygen isotopes in stalagmites in China, suggesting that East Asian summer monsoon precipitation was governed by Northern Hemisphere summer insolation on orbital timescales. However, the estimated winter temperatures were higher during interglacials and lower during glacials, showing an eccentricity cycle. This suggests that the temperature variation reflected winter monsoon variability.

Eolian quartz flux variations in Cheju Island, Korea, during the last 6500 yr and a possible Sun–monsoon linkage

2005 ◽  
Vol 64 (1) ◽  
pp. 12-20 ◽  
Author(s):  
Jaesoo Lim ◽  
Eiji Matsumoto ◽  
Hiroyuki Kitagawa
Keyword(s):  
Asian Monsoon ◽  
East Asian Monsoon ◽  
East Asian ◽  
Source Areas ◽  
Term Variation ◽  
History Of ◽  
Insolation Change ◽  
Cheju Island ◽  
Quartz Flux

AbstractWe have obtained a high-resolution sedimentary record covering the last 6500 yr from a maar in Cheju Island, Korea, in order to reconstruct the history of variations in the eolian quartz flux (EQF) and hence Asian dust. The long-term variation of EQF reveals three intervals: a period of high EQF (4000–2000 cal yr B.P.) and two periods of low EQF (6500–4000 cal yr B.P. and 2000 cal yr B.P. to present), which have been affected by the East Asian monsoon due to insolation change and the cold air activity in high latitudes correlated with polar high-pressure systems. This long-term variation is superimposed by millennial- and centennial-scale fluctuations with periodicities of 1137, 739, 214, 162, 137, 127, and 111 yr, implying drier conditions in the source areas in China. The detrended EQF record correlates visually and statistically (cross-spectral analysis) with the atmospheric Δ14C record (solar proxy). The centennial-scale variability in EQF may be affected by the solar activity through the Sun–East Asian monsoon linkage.

Long-term simulation of large-scale urbanization effect on the East Asian monsoon

2013 ◽  
Vol 129 (3-4) ◽  
pp. 511-523 ◽  
Author(s):  
Jin-Ming Feng ◽  
Yong-Li Wang ◽  
Zhu-Guo Ma
Keyword(s):  
Large Scale ◽  
Asian Monsoon ◽  
East Asian Monsoon ◽  
East Asian ◽  
Urbanization Effect

scholarly journals Water pH and temperature in Lake Biwa from MBT'/CBT indices during the last 280 000 years

2014 ◽  
Vol 10 (5) ◽  
pp. 1843-1855 ◽  
Author(s):  
T. Ajioka ◽  
M. Yamamoto ◽  
K. Takemura ◽  
A. Hayashida ◽  
H. Kitagawa
Keyword(s):  
Asian Monsoon ◽  
Lake Biwa ◽  
East Asian Monsoon ◽  
Summer Precipitation ◽  
Summer Temperature ◽  
Pollen Assemblage ◽  
Central Japan ◽  
Monsoon Variability ◽  
Water Ph ◽  
Precipitation Variation

Abstract. We generated a 280 000 yr record of water pH and temperature in Lake Biwa, central Japan, by analysing the methylation index (MBT′) and cyclisation ratio (CBT) of branched tetraethers in sediments from piston and borehole cores. Our aim was to understand the responses of precipitation and air temperature in central Japan to the East Asian monsoon variability on orbital timescales. Because the water pH in Lake Biwa is determined by phosphorus and alkali cation inputs, the record of water pH should indicate the changes in precipitation and temperature in central Japan. Comparison with a pollen assemblage in a Lake Biwa core suggests that lake water pH was determined by summer temperature in the low-eccentricity period before 55 ka, while it was determined by summer precipitation in the high-eccentricity period after 55 ka. From 130 to 55 ka, the variation in lake pH (summer precipitation) lagged behind that in summer temperature by several thousand years. This perspective is consistent with the conclusions of previous studies (Igarashi and Oba, 2006; Yamamoto, 2009), in that the temperature variation preceded the precipitation variation in central Japan.

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.

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