Binggui Cai
Fujian Normal University, College of Geographical Sciences, Faculty Member
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Studies have shown that East Asia experienced several abrupt centennial‐scale weak monsoonal events in the early Holocene. However, the timing and structure of these climate events remain unclear due to the lack of precisely dated and... more
Studies have shown that East Asia experienced several abrupt centennial‐scale weak monsoonal events in the early Holocene. However, the timing and structure of these climate events remain unclear due to the lack of precisely dated and highly resolved records. In this study, we present a well‐dated high‐resolution East Asia summer monsoon record from 11.32 to 10 ka BP based on two coeval stalagmites, one of which developed clear annual lamina, from Shihua Cave, northern China. Stalagmite δ18O records show 2 weak summer monsoon events at 10.9 and 10.3 ka. The 10.9‐ka event occurred from 10.93 to 10.79 ka BP for ∼140 years and features a “W”‐shaped structure. The 10.3‐ka event, also known as the ice‐rafted debris event 7 in the North Atlantic, lasted ∼260 years with an asymmetric double‐plunging structure. The two events are concurrent with the cold conditions in Greenland ice core record, indicating a close correlation between East Asia summer monsoon and North Atlantic climate. Spect...
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We present a new teak ( Tectona grandis L.f.) tree-ring stable oxygen isotope (δ18OTR) chronology from Mae Tuen (MT) site, Tak province, northwestern Thailand at inter-annual (167-year, A.D.1850–2016) and intra-annual (A.D.2006–2016)... more
We present a new teak ( Tectona grandis L.f.) tree-ring stable oxygen isotope (δ18OTR) chronology from Mae Tuen (MT) site, Tak province, northwestern Thailand at inter-annual (167-year, A.D.1850–2016) and intra-annual (A.D.2006–2016) timescales. The inter-annual δ18OTR chronology showed a significant negative correlation ( r = −0.678, p < 0.01) with the May–October amount of regional rainfall obtained from CRU TS4.03. We established a linear regression model that explained 46.0% of the actual rainfall variance and reconstructed monsoon season rainfall back to A.D.1850. The seasonal variations in moisture conditions were reflected in inter-annual δ18OTR variability. The rainfall amount and δ18O in precipitation (δ18Op) mainly controlled intra-annual variations in teak δ18OTR. These results show that the variation in Thai teak δ18OTR is dominated by rainfall, highlighting the strength of δ18OTR as a monsoon rainfall proxy.
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This paper analyzes the karst landscape of Southeastern Serbia, Mount Kalafat. The evaluation of five representative caves was performed using M-GAM (modified geosite assessment model) and the perspectives and potentials of karst-based... more
This paper analyzes the karst landscape of Southeastern Serbia, Mount Kalafat. The evaluation of five representative caves was performed using M-GAM (modified geosite assessment model) and the perspectives and potentials of karst-based geotourism were presented, through speleology, paleoclimate, and archaeology. Moreover, a unique proposal was presented in the form of a karst protection project through the establishment of a karst theme park. Although there are other attractive karst regions in Serbia, Mount Kalafat has been taken as a study area, due to the willingness of the local management structures and authorities to support projects concerning the protection of geoheritage and the development of karst-based geotourism. The results of the research indicate the evident values of the karst geoheritage and geotourism potentials that can become significant indicators for the development of sustainable geotourism and geoconservation in this area. Thus, precise measures and sustainable strategies that could define the geoethical concept of geotourism development have been presented in this paper.
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The past climate in northwestern Thailand remains insufficiently understood because of the limitation of climate proxies. We present a new record of paleoclimate activity during 2050–1551 years BP (before the present), based on the... more
The past climate in northwestern Thailand remains insufficiently understood because of the limitation of climate proxies. We present a new record of paleoclimate activity during 2050–1551 years BP (before the present), based on the analysis of the oxygen isotope ratios (δ18O) of tree-ring cellulose in ancient teak log coffins excavated from Namjang Cave in Mae Hong Son Province, northwestern Thailand. The ages of the teak log coffin samples were determined using C-14 dating. The average CoffinNJ δ18O value was 23.48 ± 0.77‰, values ranging from 21.23 to 25.42‰. The mean May–October (MO) rainfall reconstructed from the CoffinNJ δ18O data was 274 mm. The mean May–October (MO) rainfall data showed significant negative correlations with stalagmite δ18O data from Laos (r = − 0.254, p < 0.01), highlighting the existence of a weak monsoon from 291 to 294 AD and strong monsoon in 132 AD and 142 AD. Additionally, the MO rainfall data showed a significant positive correlation with reconstructed rainfall in Tibet (r = 0.347, p < 0.01). Spectral analysis of the CoffinNJ δ18O values revealed centennial cycles related to the sunspot number. The CoffinNJ δ18O values have a positive significant correlation with the sunspot number (r = 0.410, p < 0.01) over the entire period. Moreover, we found a highly significant positive correlation (r = 0.644, p < 0.01) between the CoffinNJ δ18O values and stalagmite δ18O values from Wanxiang Cave, China, and this correlation is related variations in the Asian monsoon. We conclude that the CoffinNJ δ18O data reflect the Asian monsoon from 2000 years ago and have the potential to be a paleoclimate proxy in northwestern Thailand.
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The Edwards Aquifer (EA) in Central Texas provides water supply for over two million people and contains springs that are hydrologically and ecologically important to the region. The residence time of groundwater in the EA ranges from a... more
The Edwards Aquifer (EA) in Central Texas provides water supply for over two million people and contains springs that are hydrologically and ecologically important to the region. The residence time of groundwater in the EA ranges from a few days to many thousands of years, since water in the aquifer is contained and transported within both matrix porosity and large conduits. In this study, stable isotopes of water from five springs are investigated for tracing the origin of water and hydrological processes in the EA system during 2017–2019. There is a quick response of the isotopic signals measured at these springs to changes in the isotopic compositions of precipitation. By utilizing an isotope mixing model, we have identified sources of water for these springs with a bi-modal distribution of groundwater supply in the EA: water supplied from deep groundwater with a longer residence time (an average of 67%) and supplemental epikarst interflow with a shorter residence time (an averag...
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There are limited coral-based paleoclimate records in the Gulf of Thailand to date. Therefore, in this study we present preliminary data on the stable oxygen isotopic (δ18O) composition of the modern coral genus Porites from Samaesan and... more
There are limited coral-based paleoclimate records in the Gulf of Thailand to date. Therefore, in this study we present preliminary data on the stable oxygen isotopic (δ18O) composition of the modern coral genus Porites from Samaesan and Ngam Islands. Two corals were analyzed that grew between 1997 and 2009 AD, and 1996 and 2010 AD, respectively. The annual growth rate was an average of 12.33 mm yr-1. Two δ18O profiles showed a good correlation in pattern and isotopic range. Correlational analyses indicated that coral δ18O is a robust proxy for the sea surface temperature (SST), which was supported by significantly negative correlations between skeleton δ18O and SSTs. These seasonal calibrations suggested a temperature dependence of 0.13 and 0.15 ‰ °C-1. The growth rate of one skeleton was positively correlated with its δ18O, but this relationship was not identified in the others, indicating an intercolony variability in the growth rate effect on δ18O. The short-term variations in E...
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We developed a stable oxygen isotope chronology of tree-ring alpha cellulose (δ18OTR) from archaeological teak (Tectona grandis L.f.) samples from Mae Hong Son (MHS) province, northwestern Thailand. The samples were collected from ancient... more
We developed a stable oxygen isotope chronology of tree-ring alpha cellulose (δ18OTR) from archaeological teak (Tectona grandis L.f.) samples from Mae Hong Son (MHS) province, northwestern Thailand. The samples were collected from ancient coffins belonging to the log coffin culture excavated at the Ban Rai rock shelter (BR). The chronology spans a period of 283 years in the late Holocene (AD14–296). The oxygen isotopic composition of BR δ18OTR ranged from 21.15‰ to 26.31‰. Since δ18OTR variations in Thailand teak can be used as indicators for precipitation amount during the rainy summer monsoon season, our chronology can be used as a proxy for regional late Holocene hydroclimate variability. This is confirmed by a significant positive correlation of our BR δ18OTR record with a stalagmite δ18O record from Klang cave, southern Thailand (r = 0.303, p
Research Interests: Geology and Quaternary
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ABSTRACT The Upper Cibolo Creek (UCC) karst watershed in Central Texas, USA, represents a portion of the drainage area that supplies water to the recharge zone for the Edwards Aquifer. However, the surface water–groundwater interactions... more
ABSTRACT The Upper Cibolo Creek (UCC) karst watershed in Central Texas, USA, represents a portion of the drainage area that supplies water to the recharge zone for the Edwards Aquifer. However, the surface water–groundwater interactions along the UCC are not well quantified, and the hydraulic interactions are important for water budget and water quality of the aquifer. In this study, we investigated the evolution of hydrochemical and isotopic signatures (δ 18O, δ 2H and d-excess) from precipitation, surface water to groundwater in the UCC watershed from 2017 to 2019, and investigated surface water–groundwater interactions using samples from 14 creeks/spring sites. Factor analysis for the observed parameters demonstrates that changes in water hydrochemistry are primarily controlled by human activity, precipitation input, and water–rock interaction. Hierarchical clustering analysis of temporal isotope variations confirms that significant surface water–groundwater interactions occur in the UCC watershed. We identified relationships between nitrate concentrations at creek/spring sites and land-use conditions, and nitrate input sources were determined utilizing the dual-isotope analyses (δ 15N and δ 18O) of nitrate. This study provides capacity for a more precise assessment of water resources and water quality in Central Texas.
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Abstract Stalagmite oxygen isotope (δ18O) record has been widely used in characterizing Asian Monsoon variations. In southwest (SW) China, although the stalagmite δ18O was usually suggested as a precipitation proxy, it remains a subject... more
Abstract Stalagmite oxygen isotope (δ18O) record has been widely used in characterizing Asian Monsoon variations. In southwest (SW) China, although the stalagmite δ18O was usually suggested as a precipitation proxy, it remains a subject of debate. Here we present two replicated, high-precise-dated stalagmite δ18O records for the interval 1710–2003 AD from Yunnan province, SW China. The stalagmite δ18O shows no correlation with the local monsoon precipitation, but a significantly positive correlation with the Pacific Decadal Oscillation (PDO) index. It demonstrates that the stalagmite δ18O in SW China is most likely influenced by the atmospheric circulation associated with the PDO through the upstream depletion mechanism. During the warm (cold) PDO period, the deficit rainfall over India would make the δ18O of water vapor transporting to SW China less (more) negative due to the weaker Rayleigh distillation process, which would lead to the less (more) negative stalagmite δ18O. Consequently, the stalagmite δ18O in SW China is suitable to reconstruct the PDO variations. It is important to note that the other factors, such as El Nino–Southern Oscillation (ENSO) or sea surface temperature (SST) also possibly affect the stalagmite δ18O in SW China, and the relationship between them requires further studies.
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The past climate in northwestern Thailand remains insufficiently understood because of the limitation of climate proxies. We present a new record of paleoclimate activity during 2050-1551 years BP (before the present), based on the... more
The past climate in northwestern Thailand remains insufficiently understood because of the limitation of climate proxies. We present a new record of paleoclimate activity during 2050-1551 years BP (before the present), based on the analysis of the oxygen isotope ratios (δ 18 O) of tree-ring cellulose in ancient teak log coffins excavated from Namjang Cave in Mae Hong Son Province, northwestern Thailand. The ages of the teak log coffin samples were determined using C-14 dating. The average CoffinNJ δ 18 O value was 23.48 ± 0.77‰, values ranging from 21.23 to 25.42‰. The mean May-October (MO) rainfall reconstructed from the CoffinNJ δ 18 O data was 274 mm. The mean May-October (MO) rainfall data showed significant negative correlations with stalagmite δ 18 O data from Laos (r = − 0.254, p < 0.01), highlighting the existence of a weak monsoon from 291 to 294 AD and strong monsoon in 132 AD and 142 AD. Additionally, the MO rainfall data showed a significant positive correlation with ...
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Ancient teak log coffins found in Namjang (NJ) Cave, Pang Ma Pha district of Mae Hong Son province in Northwestern (NW) Thailand, were dated using a combination of C-14 dating and cross-dating techniques. The longest tree-ring width... more
Ancient teak log coffins found in Namjang (NJ) Cave, Pang Ma Pha district of Mae Hong Son province in Northwestern (NW) Thailand, were dated using a combination of C-14 dating and cross-dating techniques. The longest tree-ring width chronology (i.e., the Coffin NJ index) in Thailand covered a 477-year period from 106 BC to AD 371. The ages of the NJ log coffins fell within the log coffin culture epoch in NW Thailand. The NJ coffins are considered to belong to the second component of the log coffin culture period in NW Thailand, which began from approximately 2100 BP to 1200 BP. Spectral analysis of the Coffin NJ index displayed a decadal periodicity of 11.2 years, similar to the well-known 11-year periodic change in the sunspot cycle. A positive relationship ( r = 0.31, p < 0.035) was observed between the Coffin NJ index and sunspot number for the entire period from 110 BC to AD 370, particularly during the period of AD 191–370 ( r = 0.48, p < 0.045). Comparisons with speleothem proxies sensitive to changes in solar activity showed relationships between the Coffin NJ index and speleothem parameters (layer thickness: r = − 0.50, p < 0.001 and δ 18 O: r = 0.40, p < 0.001). The results confirmed that the ancient teak trees in this study might have responded, at least partly, to solar variation. The ring widths of the teak log coffins proved to be a promising proxy for studying the evolution of coffin culture and past climate change in this area.
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Abstract Greenland Interstadial-21 (GIS 21), with a centennial-scale precursor event and a “rebound-type” event, was one of the longest warm millennial-scale events recorded in Greenland ice cores during the last glacial period. Precise... more
Abstract Greenland Interstadial-21 (GIS 21), with a centennial-scale precursor event and a “rebound-type” event, was one of the longest warm millennial-scale events recorded in Greenland ice cores during the last glacial period. Precise determination of its timing and duration can improve our understanding of regional/global climate correlations over Marine Isotope Stages (MIS) 5b/5a and 5a/4. Here, a precisely 230Th-dated decadally-resolved stalagmite δ18O record from Xianyun Cave, Fujian Province, southeastern China, is utilized to reconstruct the sub-millennial-scale changes in East Asian summer monsoon (EASM) from 87.6 to 76.3 kyr BP (before 1950 CE), covering Chinese Interstadial 21 (CIS 21) event. A comparison of spatially-separated Chinese speleothem records during GIS 21 shows a decrease in speleothem δ18O values from southeastern China to northwestern China. These δ18O spatial gradients could be attributed to the “rainout effect” and the amplification mechanism of the seasonal variations of precipitation δ18O. Moreover, Xianyun δ18O record captures the precursor event centered at 85.3 ± 0.3 kyr BP concurrent with the corresponding event in ice cores, revealing an atmospheric teleconnection between high and low latitudes. Unlike gradual cooling at the Greenland and Antarctic ice core records during mid-GIS 21, the Xianyun record reveals a relatively strong monsoon phase. We speculate that the cooling of the Southern Hemisphere (SH) may influence EASM activity through the intensification of cross-equatorial flow and weaken the impact of Northern Hemisphere (NH) high latitude climate, thus pointing to the role of SH climate on EASM on millennial-scale.
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Stalagmites provide one of the few high-quality proxy records of the Thailand monsoon. The Namjang (NJ) cave (19°40′30″N, 98°12′12″E; 923 m a.s.l.), which is situated in the data-scarce region of northwestern Thailand, serves as a unique... more
Stalagmites provide one of the few high-quality proxy records of the Thailand monsoon. The Namjang (NJ) cave (19°40′30″N, 98°12′12″E; 923 m a.s.l.), which is situated in the data-scarce region of northwestern Thailand, serves as a unique and important site that offers great potential for multi-proxy climate reconstruction. We present new data on stable oxygen isotopic (δ 18 O) compositions and growth rates of aragonite stalagmites based on an in situ cave and climate monitoring study performed between August 2012 and October 2013. The dominant factors that control the variations in the δ 18 O values of rainfall, drip water, and modern aragonite precipitate as well as the variations in the modern speleothem deposition rates and drip water hydrochemical properties were determined to correctly interpret the climatic signals of the parameters that are derived from speleothems. The intraseasonal variations in rainfall δ 18 O values were faithfully recorded from cave drip water isotopic signals. The monthly mean values of δ 18 O in cave drip water were lower in the rainy season and higher in the dry seasons and shifted from approximately − 4 in the early rainy months to approximately − 6‰ in the late rainy months. These variations have implications for the use of speleothem δ 18 O from the NJ cave as a proxy of the seasonal variations in monsoon rainfall δ 18 O and changes in moisture source trajectories. The deposition rates of modern speleothem deposits are primarily controlled by drip water flow rates, which are linked to the amount of water recharge in the cave during the summer monsoon season. There was a significant correlation between the drip rate and amount of carbonate precipitation for the drip sites NJ-1 ( r = 0.54, p < 0.040) and NJ-1202 ( r = 0.76, p < 0.004). Combinations of different parameters and proxies from this area could provide the potential for the further development of multi-proxy climate reconstructions over different time scales.
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Thailand is situated in a transition zone of overlap between the Indian monsoon (IM) and the western North Pacific (WNP) monsoon. The region serves as an important area to study the influences of different moisture sources. This study... more
Thailand is situated in a transition zone of overlap between the Indian monsoon (IM) and the western North Pacific (WNP) monsoon. The region serves as an important area to study the influences of different moisture sources. This study presents the first stable oxygen isotope analysis on seven teak (Tectona grandis Linn.) trees collected from Phrae Province in northern Thailand at different temporal resolutions. Isotopic analyses of teak tree rings at both annual and sub-annual timescales reflected the variations in their source water oxygen isotope ratios (δ¹⁸O, i.e., rainfall) to different degrees (Annual scale: r = 0.31, p < 0.05, Monthly scale: r = 0.63, p < 0.01). A 146-year-long annually resolved tree-ring cellulose δ¹⁸O series, spanning between AD 1871 and 2016, exhibited moderate negative relationships with both local (r = −0.58, p < 0.01) and regional rainfall amounts, representing the climatology of rainfall totals during the entire summer monsoon period from May to October. A spatial correlation analysis between monthly resolved tree-ring cellulose δ¹⁸O with large-scale Climate Prediction Center (CPC), Outgoing Longwave Radiation (OLR), and Merged Analysis of Precipitation (CMAP) datasets, as well as an air mass backward trajectory analysis, indicated that the intraseasonal tree-ring cellulose δ¹⁸O values reflected changes in moisture originating from the Indian and Pacific Oceans, rather than the amount of local precipitation. These results imply that variations in northern Thai teak cellulose δ¹⁸O values are modulated not only by the local rainfall amount but also by large-scale convection, which varies between different seasons and over time. Advance knowledge of the regional monsoons in the transition area can therefore lead to a broad and complete understanding of the entire Asian monsoon circulation.
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Thailand monsoon is located in the transition zone between the Indian and western North Pacific monsoons. Assuredly, proxy climate data from this area could improve our understanding of the nature of Asian monsoon. Tree rings and... more
Thailand monsoon is located in the transition zone between the Indian and western North Pacific monsoons. Assuredly, proxy climate data from this area could improve our understanding of the nature of Asian monsoon. Tree rings and stalagmites from this area are two potential materials for high-resolution paleoclimate reconstructions. However, a comprehensive understanding of these multiproxy records is still a challenge. In this study, a 76-year tree ring cellulose oxygen isotope value (δ18O) of a teak tree from northwestern Thailand was developed to test its climatic significance and potential for multiproxy climate reconstruction. The results indicate that the interannual variability of cellulose δ18O can be interpreted as a proxy of rainfall in the early monsoon season (May to July rainfall) as well as a proxy of relative humidity. Comparisons with speleothem proxies from the same locality and tree ring records from wider geographical areas provide a basis for developing a multiproxy approach. The results from a teleconnection analysis reveal that the El Niño-Southern Oscillation (ENSO) is an important climate mode that impacts monsoon rainfall in Thailand. High-quality proxy records covering recent decades are critically important not only to improve proxy data calibrations but also to provide a better understanding of teleconnections within the modern atmosphere. Preliminary findings demonstrated the potential of tree ring stable isotopes from Thai teak to develop multiproxy climate reconstruction.
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Abstract Tree-ring variability of submerged wood specimens in coastal areas provides important clues about sea level change and climate variability of the past. We dated submerged wood samples from coastal Fujian province in China using... more
Abstract Tree-ring variability of submerged wood specimens in coastal areas provides important clues about sea level change and climate variability of the past. We dated submerged wood samples from coastal Fujian province in China using the radiocarbon methods and investigated their tree-ring variability. The submerged wood samples from the Shenhu Bay that date to the early Holocene (∼8000 calibrated years B.P.) may be related to the rise of the sea level after the Last Glacial Maximum (LGM). The submerged wood samples from the Qianhu Bay site dated to the Marine Isotope Stage 3 (MIS 3) (>40,000 calibrated years B.P.). Most of the submerged wood samples are from coniferous trees with frequent branching tree rings. Frequent branching tree rings in this region are mostly found from the currently endangered coniferous species with narrow ecological amplitude at humid sites. Tree rings of the submerged sample show conspicuous interdecadal variability (∼20 years) than interannual variations, which differs from modern tree rings of nearby regions which have stronger interannual and multi-decadal variability. Our study highlights the potential to use submerged samples of coastal Southeast China for paleoclimate studies.
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Thailand has been regarded as a transition zone between the Indian and western North Pacific monsoons which produce most of the precipitation in this area and sustain large-scale agricultural activities. Their different moisture sources... more
Thailand has been regarded as a transition zone between the Indian and western North Pacific monsoons which produce most of the precipitation in this area and sustain large-scale agricultural activities. Their different moisture sources and associated transport trajectories could result in distinguishable seasonal variations in rainfall oxygen isotopes (δ18O). Knowledge about seasonal variability in Thailand monsoon could facilitate agricultural water management and improve our understanding of the Asian monsoon system. In this study, a detailed examination of the intra-seasonal variability of tree-ring cellulose δ18O in teak trees from Northwestern Thailand was performed. The results show clear intra-seasonal variability in cellulose δ18O, with heavier values in the early rainy season and much lighter values in the later rainy season. Climate correlation analysis indicates that there is a significant and positive correlation between sub-seasonal variation in cellulose δ18O and rain...
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Research Interests: Earth Sciences, Diatoms as indicators, Diatoms, History and archaeology, Late Holocene, and 12 moreQSR, Sediment Traps, East Asian summer monsoon, Southern Hemisphere, Early Holocene, Quaternary Science Reviews, Spatial Variation, Turbulent Mixing, Relative Abundance, Wind Speed, Tropical Climate, and Arctic Oscillation
There are limited coral-based paleoclimate records in the Gulf of Thailand to date. Therefore, in this study we present preliminary data on the stable oxygen isotopic (δ 18 O) composition of the modern coral genus Porites from Samaesan... more
There are limited coral-based paleoclimate records in the Gulf of Thailand to date. Therefore, in this study we present preliminary data on the stable oxygen isotopic (δ 18 O) composition of the modern coral genus Porites from Samaesan and Ngam Islands. Two corals were analyzed that grew between 1997 and 2009 AD, and 1996 and 2010 AD, respectively. The annual growth rate was an average of 12.33 mm yr -1 . Two δ 18 O profiles showed a good correlation in pattern and isotopic range. Correlational analyses indicated that coral δ 18 O is a robust proxy for the sea surface temperature (SST), which was supported by significantly negative correlations between skeleton δ 18 O and SSTs. These seasonal calibrations suggested a temperature dependence of 0.13 and 0.15 ‰ °C -1 . The growth rate of one skeleton was positively correlated with its δ 18 O, but this relationship was not identified in the others, indicating an intercolony variability in the growth rate effect on δ 18 O. The short-term...
Stalagmite grey level provides limited information about palaeoclima as its interpretation depends on numerous factors. One of the best approaches entails calibrating grey level sequences with instrumental climate data. In this study,... more
Stalagmite grey level provides limited information about palaeoclima as its interpretation depends on numerous factors. One of the best approaches entails calibrating grey level sequences with instrumental climate data. In this study, grey level variation covering a 105-year span was analysed in a lamina stalagmite, known as Namjang1 (NJ1), from Namjang cave (98° 12 12 E, 19° 40 30 N), in north-western Thailand. The grey level time series positively correlated with the five-year running average of rainfall in October (r = 0.22, p < 0.05), the five-year running average of ratio of August to October to May to July rainfall (r = 0.38, p < 0.01), and the five-year running average of ratio of August to October and May to October rainfall (r = 0.35, p < 0.01). This indicates that the calibrated grey level record can provide a high resolution proxy of rainfall in the late monsoon season. The observed correlation between grey level and rainfall in the late monsoon season is consist...
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The East Asian winter monsoon (EAWM) not only plays an important role within the Asian climate system, but also carries cold air from the high northern latitudes across the Equator to the Southern Hemisphere, acting as a link between the... more
The East Asian winter monsoon (EAWM) not only plays an important role within the Asian climate system, but also carries cold air from the high northern latitudes across the Equator to the Southern Hemisphere, acting as a link between the polar and tropical climate systems. However, past changes of the EAWM have not been clearly established so far due to the lack of suitable proxy records. Here, we at first establish an index of the EAWM by comparing the results of a sediment trap experiment and 100-year sedimentary record from Huguang Maar Lake (HML) with modern records of the EAWM, Siberian High (SH) and Arctic Oscillation (AO). Secondly, we present a continuous record of the strength of the EAWM for the past 14,500 years based on sedimentary diatom assemblages in HML. The record is derived from fluctuations in the relative abundance of two planktonic diatom species. The link with the EAWM intensity is through high wind speeds inducing turbulent mixing, which stimulates the productivity of the meroplanktonic species Aulacoseira granulata. The diatom record of the past 14,500 years shows that the EAWM shifted from strong to weak from the early to late Holocene. This linked to both changes in winter temperature at high-latitudes and in El Niño conditions in the tropics. Our record shows that the EAWM and East Asian summer monsoon (EASM) as recorded in stalagmites, were in-phase instead of anti-correlated on orbital time scales during the Holocene. On a millennial time scales, the EAWM was anti-phase with the EASM during the Last Glacial–Holocene transition. However, during the early–middle Holocene the relationship between the EAWM and EASM shows spatial variations. In northern China, the records show significant anti-phase, but in southern China the anti-phase was not observed. During the late Holocene, we did not find any clear relationship between the EAWM and EASM. We also explored the link between the EAWM and the Australian summer monsoon (ASM). Anti-phase of the ASM with summer insolation in the Southern Hemisphere is an enigmatic exception that cannot be explained by the classic theory of insolation. During early Holocene the EAWM was in-phase with the Australian summer monsoon (ASM), which provides the first direct evidence to support the hypothesis that the intensity of the EAWM affected, at least in part, the strength of the ASM.► We present a sedimentary diatom record of the East Asian winter monsoon (EAWM). ► The EAWM shifted from strong to weak from the early to late Holocene. ► The winter and summer monsoons were not anti-correlated on orbital time scale. ► On a millennial time scale, their correlation shows spatial and temporal variability. ► Our record supports the idea of the EAWM affecting the Australian summer monsoon.
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The multimodal distribution of grains in loess and dust storm deposits has been widely reported in recent years. Our analysis demonstrates that the interaction of wind, atmospheric turbulence, and dust grain gravity along the dust... more
The multimodal distribution of grains in loess and dust storm deposits has been widely reported in recent years. Our analysis demonstrates that the interaction of wind, atmospheric turbulence, and dust grain gravity along the dust transportation path results in a multimodal grain size distribution for suspended dust. Changes in the median sizes of the coarse and medium modes are related
Research Interests: Time Series, Climate variability, East Asia, Transportation, Environmental Change, and 23 moreMultidisciplinary, Pleistocene, Quaternary, Global change, Models, Gravity, Atmospheric Turbulence, Loess, Cenozoic, Magnetic Susceptibility, Younger Dryas, Phanerozoic, Grain size distribution, Fluctuations, Geophysical, Aerodynamic Force, Dust Storm, Forcing, Turbulence Intensity, Loess Plateau, Winds, Plateau, and Glacial periods
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Northern Thailand is the most flood-prone region in Thailand during the Indian Ocean Dipole (IOD) and El Ni~no-Southern Oscillation (ENSO) events. An annual growth rate profile covering the period from 1622 to 2008 AD was derived from the... more
Northern Thailand is the most flood-prone region in Thailand during the Indian Ocean Dipole (IOD) and
El Ni~no-Southern Oscillation (ENSO) events. An annual growth rate profile covering the period from 1622
to 2008 AD was derived from the laminated stalagmite NJ-0901 from this area. By comparing stalagmite
NJ-0901 to a contemporaneous stalagmite from the same cave and correlating the growth rate of NJ-0901
with meteorological data from the most recent 100 years, the stalagmite record proved to be a paleoclimate
proxy of Thailand monsoon (TM) rainfall. This is the first annually laminated speleothem record
that has been traced back four centuries. This record provided a long-term perspective and a valuable
insight into TM rainfall and allowed us to investigate variations in the monsoon activity that was
associated with IOD and ENSO. Our results indicate that both IOD and ENSO are significant climate modes
that impact TM rainfall, but the effect of the interaction IOD and ENSO on TM rainfall remains unclear.
El Ni~no-Southern Oscillation (ENSO) events. An annual growth rate profile covering the period from 1622
to 2008 AD was derived from the laminated stalagmite NJ-0901 from this area. By comparing stalagmite
NJ-0901 to a contemporaneous stalagmite from the same cave and correlating the growth rate of NJ-0901
with meteorological data from the most recent 100 years, the stalagmite record proved to be a paleoclimate
proxy of Thailand monsoon (TM) rainfall. This is the first annually laminated speleothem record
that has been traced back four centuries. This record provided a long-term perspective and a valuable
insight into TM rainfall and allowed us to investigate variations in the monsoon activity that was
associated with IOD and ENSO. Our results indicate that both IOD and ENSO are significant climate modes
that impact TM rainfall, but the effect of the interaction IOD and ENSO on TM rainfall remains unclear.