Biogenic Silica Record in Lake Biwa of Central Japan over the Past 145,000 Years

1997 ◽  
Vol 47 (3) ◽  
pp. 277-283 ◽  
Author(s):  
Jule Xiao ◽  
Yoshio Inouchi ◽  
Hisao Kumai ◽  
Shusaku Yoshikawa ◽  
Yoichi Kondo ◽  
...  
Keyword(s):  
Time Series ◽  
Oxygen Isotope ◽  
Biogenic Silica ◽  
Lake Biwa ◽  
Silica Content ◽  
Central Japan ◽  
The Past ◽  
Last Glaciation ◽  
Diatom Productivity ◽  
Silica Flux

The record of the biogenic silica flux (BSF, g cm−2(103yr)−1) in Lake Biwa reflects changes in diatom productivity in the lake and provides information regarding changes in paleoclimatic conditions. The BSF record of Lake Biwa demonstrates five periods over the past ca. 145,000 yr when the BSF values were significantly greater than 7.5 g cm−2(103yr)−1, and five intervals when they were lower. The data imply that paleoclimatic conditions were warmer and wetter from ca. 123,000 to 115,000, 103,000 to 95,000, 88,000 to 72,000, 57,000 to 32,000 yr B.P., and around ca. 6000 yr B.P. when the BSF values were greater, and relatively dry and cold from ca. 141,000 to 123,000 yr B.P. and during intervals between two of the five warm and wet episodes when the BSF values were lower. Time series of the BSF record can be correlated with the record of biogenic silica content in Lake Baikal and the marine oxygen isotope stages 1 through 6. Furthermore, the BSF values varied with much higher amplitude during the last interglaciation than during the last glaciation, probably implying that the diatom productivity in Lake Biwa was likewise more variable and had a larger range under interglacial conditions than under glacial conditions.

Statistical Analysis of Grain Size Distribution in Pleistocene Sediments from Lake Biwa, Japan

1988 ◽  
Vol 30 (1) ◽  
pp. 12-18 ◽  
Author(s):  
Kenji Kashiwaya ◽  
Atsuyuki Yamamoto ◽  
Kaoru Fukuyama
Keyword(s):  
Time Series ◽  
Grain Size ◽  
Statistical Analysis ◽  
Size Distribution ◽  
Lake Biwa ◽  
Size Distributions ◽  
Solar Insolation ◽  
The Past ◽  
Grain Size Distributions ◽  
Milankovitch Theory

Time series of grain-size distributions from Pleistocene sediments deposited in Lake Biwa during the past 550 millennia show dominant periods of 40,000 and 20,000 yr that are very close to those predicted by the Milankovitch theory, as well as a period of about 70,000 yr not directly predicted by this theory. The 70,000-yr period is strongest, followed by the 20,000-yr period. The sequences also show that coarser particles were deposited, in general, during strong solar insolation, whereas finer particles were deposited during weak insolation.

scholarly journals A 2600-year summer climate reconstruction in central Japan by integrating tree-ring stable oxygen and hydrogen isotopes

2020 ◽  
Vol 16 (6) ◽  
pp. 2153-2172 ◽  
Author(s):  
Takeshi Nakatsuka ◽  
Masaki Sano ◽  
Zhen Li ◽  
Chenxi Xu ◽  
Akane Tsushima ◽  
...  
Keyword(s):  
Time Series ◽  
Tree Ring ◽  
Isotope Ratios ◽  
Tree Age ◽  
Central Japan ◽  
The Past ◽  
Summer Climate ◽  
Age Trends ◽  
Past Summer ◽  
Tree Ring Cellulose

Abstract. Oxygen isotope ratios (δ18O) of tree-ring cellulose are a novel proxy for summer hydroclimate in monsoonal Asia. In central Japan, we collected 67 conifer wood samples, mainly Chamaecyparis obtusa, with ages encompassing the past 2600 years. The samples were taken from living trees, archeological wood, architectural wood, and buried logs. We analyzed stable isotope ratios of oxygen (δ18O) and hydrogen (δ2H) in tree-ring cellulose in these samples (more than 15 000 rings in total) without using a pooling method and constructed a statistically reliable tree-ring cellulose δ18O time series for the past 2500 years. However, there were distinct age trends and level offsets in the δ18O record, and cellulose δ18O values showed a gradual decrease as an individual tree matures. This suggested it is difficult to establish a cellulose δ18O chronology for low-frequency signals by simple averaging of all the δ18O time series data. In addition, there were opposite age trends in the cellulose δ2H, and δ2H gradually increased with tree age. There were clear positive correlations in the short-periodicity variations between δ18O and δ2H, probably indicating a common climate signal. A comparison of the δ18O and δ2H time series in individual trees with tree-ring width suggested that the opposite age trends of δ18O and δ2H are caused by temporal changes in the degree of post-photosynthetic isotope exchange with xylem water (physiological effect), accompanied by changes in stem growth rate that are influenced by human activity in the forests of central Japan. Based on the assumptions that cellulose δ18O and δ2H vary positively and negatively with constant proportional coefficients due to climatological and physiological effects, respectively, we solved simultaneous equations for the climatological and physiological components of variations in tree-ring cellulose δ18O and δ2H in order to remove the age trend. This enabled us to evaluate the climatic record from cellulose δ18O variations. The extracted climatological component in the cellulose δ18O for the past 2600 years in central Japan was well correlated with numerous instrumental, historical, and paleoclimatological records of past summer climate at various spatial and temporal scales. This indicates that integration of tree-ring cellulose δ18O and δ2H data is a promising method to reconstruct past summer climate variations on annual to millennial timescales, irrespective of the growth environment. However, analytical and statistical methods need to be improved for further development of this climate proxy.

scholarly journals Fluvial Quartz Flux to Lake Biwa of Central Japan over the Past 145,000 Years.

1997 ◽  
Vol 36 (1) ◽  
pp. 17-27 ◽  
Author(s):  
Jule Xiao ◽  
Yoshio Inouchi ◽  
Hisao Kumai ◽  
Shusaku Yoshikawa ◽  
Yoichi Kondo ◽  
...  
Keyword(s):  
Lake Biwa ◽  
Central Japan ◽  
The Past ◽  
Quartz Flux

Eolian Quartz Flux to Lake Biwa, Central Japan, over the Past 145,000 Years

1997 ◽  
Vol 48 (1) ◽  
pp. 48-57 ◽  
Author(s):  
Jule Xiao ◽  
Yoshio Inouchi ◽  
Hisao Kumai ◽  
Shusaku Yoshikawa ◽  
Yoichi Kondo ◽  
...  
Keyword(s):  
Lake Biwa ◽  
East Asian Winter Monsoon ◽  
East Asian ◽  
Winter Monsoon ◽  
Central Japan ◽  
Chinese Loess ◽  
Asian Winter Monsoon ◽  
The Past ◽  
Source Regions ◽  
Quartz Flux

Eolian quartz flux (EQF, g cm−2(103 yr)−1) to Lake Biwa, central Japan, provides direct information on variations of the East Asian winter monsoon. Lake Biwa sediments spanning the past ca. 145,000 yr are characterized by two main periods when EQF values were significantly greater than 5.50 g cm−2(103 yr)−1, and two main intervals during which EQF values were lower. Two periods with EQF values >5.50 g cm−2(103 yr)−1occurred from ca. 145,000 to 125,000 and 73,000 to 13,000 yr B.P., while times of lower EQF values occurred from ca. 125,000 to 73,000 yr B.P. and around ca. 5500 yr B.P. Between ca. 125,000 and 73,000 yr B.P., three minimum EQF values and two intervening peaks of slightly higher EQF values are recorded. EQF increased markedly from ca. 73,000 to 13,000 yr B.P., whereas between ca. 53,000 and 20,000 yr B.P. the values recorded were relatively lower than those recorded during either the preceding or the subsequent episodes. The data imply that the East Asian winter monsoon strengthened during the periods when EQF values were high, and weakened during the intervals with low EQF values. The EQF record of Lake Biwa can be correlated with the grain-size record of the quartz fraction in Chinese loess and with the SPECMAP marine δ18O record. However, the EQF record apparently lags ca. 5000 yr behind the loess and δ18O records during stage 6/5 and 2/1 transitions and ca. 10,000 yr during stage 5/4 transition. These apparent lags could be due to problems with the chronology; alternatively, they may imply that the eolian quartz flux depended more on the extent of dust source regions than on wind intensity during these transitions.

scholarly journals Reconstruction of multi-millennial summer climate variations in central Japan by integrating tree-ring cellulose oxygen and hydrogen isotope ratios

2020 ◽  
Author(s):  
Takeshi Nakatsuka ◽  
Masaki Sano ◽  
Zhen Li ◽  
Chenxi Xu ◽  
Akane Tsushima ◽  
...  
Keyword(s):  
Time Series ◽  
Tree Ring ◽  
Isotope Ratios ◽  
Growth Effect ◽  
Climate Variations ◽  
Central Japan ◽  
The Past ◽  
Summer Climate ◽  
Age Trends ◽  
Tree Ring Cellulose

Abstract. Oxygen isotope ratios (δ18O) of tree-ring cellulose are a novel proxy of summer hydroclimate in monsoonal Asia. In central Japan, we collected 67 conifer wood samples, mainly Chamaecyparis obtusa, with ages encompassing the past 2,600 yr. The samples were taken from living old trees, excavated archeological wood, old architectural wood, and naturally buried logs. We analyzed stable isotope ratios of oxygen (δ18O) and hydrogen (δ2H) in tree-ring cellulose in these samples without using a pooling method, and constructed a statistically reliable tree-ring cellulose δ18O time-series for the past 2,500 yr. However, there were distinct age trends and level offsets in the δ18O record, and cellulose δ18O values showed a gradual decrease as an individual tree matures. This suggested it is difficult to establish a cellulose δ18O chronology for low-frequency signals by simple averaging of all the δ18O time-series data. However, there were opposite age trends in the cellulose δ2H, and δ2H gradually increased with tree age. There were clear positive correlations in the short periodicity variations between δ18O and δ2H, probably indicating a common climate signal. A comparison of the δ18O and δ2H time-series in individual trees with tree-ring width suggested that the opposite age trends of δ18O and δ2H are caused by temporal changes in the degree of post-photosynthetic isotope exchange with xylem water, accompanied by changes in stem growth rate (growth effect) that are influenced by human activity in the forests of central Japan. Based on the assumptions that cellulose δ18O and δ2H vary positively and negatively with constant proportional coefficients due to climate variations and the growth effect, respectively, we solved simultaneous equations for the climatological and physiological components of variations in tree-ring cellulose δ18O and δ2H in order to remove the age trend (growth effect). This enabled us to evaluate the climatic record from cellulose δ18O variations. The extracted climatological component in the cellulose δ18O for the past 2,600 yr in central Japan was well correlated with numerous instrumental, historical, and paleoclimatological records of past summer climate at various spatial and temporal scales. This indicates that integration of tree-ring cellulose δ18O and δ2H data is a promising method to reconstruct past summer climate variations on annual to millennial time-scales, irrespective of the growth affect. However, analytical and statistical methods need to be improved for further development of this climate proxy.

scholarly journals Evaluating the performance of multivariate indicators of resilience loss

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Els Weinans ◽  
Rick Quax ◽  
Egbert H. van Nes ◽  
Ingrid A. van de Leemput
Keyword(s):  
Time Series ◽  
Complex Systems ◽  
Multivariate Time Series ◽  
Tipping Points ◽  
Physical And Mental Health ◽  
One Dimensional ◽  
Slowing Down ◽  
The Past ◽  
Technological Developments ◽  
Resilience Indicators

AbstractVarious complex systems, such as the climate, ecosystems, and physical and mental health can show large shifts in response to small changes in their environment. These ‘tipping points’ are notoriously hard to predict based on trends. However, in the past 20 years several indicators pointing to a loss of resilience have been developed. These indicators use fluctuations in time series to detect critical slowing down preceding a tipping point. Most of the existing indicators are based on models of one-dimensional systems. However, complex systems generally consist of multiple interacting entities. Moreover, because of technological developments and wearables, multivariate time series are becoming increasingly available in different fields of science. In order to apply the framework of resilience indicators to multivariate time series, various extensions have been proposed. Not all multivariate indicators have been tested for the same types of systems and therefore a systematic comparison between the methods is lacking. Here, we evaluate the performance of the different multivariate indicators of resilience loss in different scenarios. We show that there is not one method outperforming the others. Instead, which method is best to use depends on the type of scenario the system is subject to. We propose a set of guidelines to help future users choose which multivariate indicator of resilience is best to use for their particular system.

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