The Yili River Basin in Northwest China is a crucial ecological security barrier,yet it faces frequent droughts amid global climate change,posing significant threats to food security and ecological stability.However,t...The Yili River Basin in Northwest China is a crucial ecological security barrier,yet it faces frequent droughts amid global climate change,posing significant threats to food security and ecological stability.However,the spatiotemporal variations and driving mechanisms of drought in the basin remain unclear.Based on the monthly Standardized Precipitation Evapotranspiration Index(SPEI),this study employed the Run-Length theory to identify drought events in the basin during 1980-2020,applied statistical and time-series analyses to investigate the spatiotemporal variations,trends,periodicity,and persistence of drought,and explored the underlying drivers associated with meteorological factors and large-scale atmospheric circulation patterns.The results showed that droughts in the Yili River Basin are more severe in spring and summer.Droughts in the central and southwestern regions exhibit greater severity,with shorter durations and stronger intensity.Drought conditions have generally worsened(Sen’s slope=−0.146/10 yr),with notable intensification since 2005,especially in the northwestern region.Spring droughts(Sen’s slope=−0.213/10 yr)and summer droughts(Sen’s slope=−0.169/10 yr)have intensified at most stations,while autumn and winter droughts have eased.In the future,droughts are expected to alleviate overall,but summer droughts may continue to intensify.The Yili River Basin exhibits two primary drought periods of 9 yr and 21 yr,with primary periods in autumn(20 yr)and winter(20 yr)being longer than those in spring(10 yr)and summer(17 yr).Finally,droughts are impacted by both meteorological factors and large-scale atmospheric circulation patterns.Rising temperatures and uneven precipitation have intensified droughts.The SPEI exhibits a co-phase relationship with the North Atlantic Oscillation and an antiphase relationship with the East Central Tropical Pacific Sea Surface Temperature.Therefore,close monitoring and mitigation are necessary for spring and summer droughts,with a focus on the central and southwestern areas in autumn and winter.展开更多
As the first national exhibition with the theme of supply chain,China International Supply Chain Expo(hereinafter referred to as the CISCE)has already become a key spot to observe the establishment of the Chinese ente...As the first national exhibition with the theme of supply chain,China International Supply Chain Expo(hereinafter referred to as the CISCE)has already become a key spot to observe the establishment of the Chinese enterprise industry chain.During the evolution of three CISCE,the leading dairy enterprise,Yili Group(hereinafter referred to as Yili),takes the practice of the entire industry chain as a sample,clearly outlining the development trajectory of China's dairy industry from“following”to“leading”.Its explorations of indust r ial chain col laborat ion,green transformation,and global layout are prominent.Therefore,providing a good paradigm for the high-quality development of the real economy.展开更多
Gold,iron,copper,lead-zinc and other mineral exploration in West Tianshan,Xinjiang Uygur Autonomous Region,has made remarkable progress in recent years.However,due to the dispute on the tectonic division of West Tians...Gold,iron,copper,lead-zinc and other mineral exploration in West Tianshan,Xinjiang Uygur Autonomous Region,has made remarkable progress in recent years.However,due to the dispute on the tectonic division of West Tianshan,the ore-controlling factors and the regional metallogenic laws are controversial.The authors analyze regional gravity data and notice that the high-value region corresponds to the Yili ancient continent,thus the southeastern boundary of the Yili ancient continent is delineated.Comparative analysis of gravity,aeromagnetic and geologic data reveals that the Tulasu basin,where some medium to large epithermal gold deposits locate,lies above the Yili ancient continent;the Yili Carboniferous-Permian rift extends in E-W direction,numbers of copper deposits have been found in the mid-west section of the rift which lies above the Yili ancient continent,whereas few copper deposits have been discovered in the east section which is outside the Yili ancient continent.Accordingly,the Yili ancient continent may be rich in gold,copper and other metal elements;the metal-bearing hydrothermal solution moves up with the activity of magmatism,and deposits in the favorable places(the Tulasu basin and the Yili Carboniferous-Permian rift),forming numerous small and medium gold,copper deposits,as well as some large and super-large gold deposits.Therefore,the tectonic-magmatic hydrothermal zone above the Yili ancient continent should be the prospective area for epithermal gold and copper polymetallic deposits.展开更多
With the development of Internet technologies, Internet Based Information System (IBIS) arises with more advantages: Firstly, it is convenient for users to use owing to the introduction of Internet technologies. Secon...With the development of Internet technologies, Internet Based Information System (IBIS) arises with more advantages: Firstly, it is convenient for users to use owing to the introduction of Internet technologies. Secondly, it benefits greatly the data dissemination and data sharing based on Internet. The most important but not the last is that we can establish the information service network supported by its technologies and the facilities of information highway. So, it would be significant to design IBIS to realize the data collection, sharing and dissemination on Internet. There are many factors affecting regional environment. So it is not easy to realize the integrated environmental monitoring. Given this, we designed the Internet based environmental monitoring information system. By the virtue of the Internet based environmental monitoring information system, the management and storage of environmental monitoring data would be easier, which lays the foundation to actualize the environmental monitoring efficiently.展开更多
Bedding orientation measurement is a remote sensing application used in the field of geology, but the results are often unsatisfactory when the bed is dislocated along the strike direction. This paper proposes a new m...Bedding orientation measurement is a remote sensing application used in the field of geology, but the results are often unsatisfactory when the bed is dislocated along the strike direction. This paper proposes a new method called multiple-line method that is designed to improve bedding orientation measurement. This technique uses the bed as a vector, and fits the vectors as a plane to obtain the bedding orientation. This study employs the case of Yili Basin and measures 25 bedding orientations using the multiple-point and multiple-line methods, respectively. The result shows that the errors from the multiple-line method are mostly smaller than those from the multiple-point method when a bed is discontinuous.展开更多
The Quaternary sediments in the Yili Basin can serve as archives for studying the Cenozoic basin-mountain relationship. In this study, based on typical natural sections and boreholes, the surficial sediments of the Hu...The Quaternary sediments in the Yili Basin can serve as archives for studying the Cenozoic basin-mountain relationship. In this study, based on typical natural sections and boreholes, the surficial sediments of the Huocheng area were studied, and their sedimentary ages were obtained using the optically stimulated luminescence(OSL) and electron spin resonance(ESR) dating methods. These dates, combined with changes in the sedimentary facies, provided details of the neotectonic movement in the Yili Basin and adjacent areas. By dating sediments from five sections and three boreholes, we determined that the surficial sediments of the Huocheng area were mainly formed in the Late Pleistocene, with scattered instances of Holocene sediments. The surficial sediments mainly consisted of alluvial fan facies, fluvial facies, lacustrine facies, and desert facies. Based on the activity on the Hongshanzui fault and the northern margin fault of the Wusun Mountains, the Huocheng area was uplifted synchronously with the Tianshan Mountains during the last stage of the Late Pleistocene, causing the desert facies sediments to be superimposed on the former paleo-lake sediments.展开更多
In developing countries, land productivity involves little market, where the agricultural land use is mainly determined by the food demands as well as the land suitability. The land use pattern will not ensure everywh...In developing countries, land productivity involves little market, where the agricultural land use is mainly determined by the food demands as well as the land suitability. The land use pattern will not ensure everywhere enough land for certain cropping if spatial allocation just according to land use suitability. To solve this problem, a subzone and a pre-allocation for each land use are added in spatial allocation module, and land use suitability and area optimi- zation module are incorporated to constitute a whole agricultural land use optimal allocation （ALUOA） system. The system is developed on the platform .Net 2005 using ArcGIS Engine （version 9.2） and C# language, and is tested and validated in Yili watershed of Xinjiang Region on the newly reclaimed area. In the case study, with the help of soil data obtained from 69 points sampled in the fieldwork in 2008, main river data supplied by the Department of Water Resources of Xinjiang Uygur Autonomous Region in China, and temperature data provided by Data Center for Resources and Environmental Sciences, Chinese Academy of Sciences, land use suitability on eight common crops are evaluated one by one using linear weighted summation method in the land use suitability model. The linear pro- gramming （LP） model in area optimization model succeeds to give out land area target of each crop under three scenarios. At last, the land use targets are allotted in space both with a six subzone file and without a subzone file. The resuits show that the land use maps with a subzone not only ensure every part has enough land for every crop, but also gives a more fragmental land use pattern, with about 87.99% and 135.92% more patches than the one without, while at the expense of loss between 15.30% and 19.53% in the overall suitability at the same time.展开更多
The Yili Block in the Western Tianshan orogen is a key area for understanding the early crustal formation and evolution of the Central Asian orogenic belt,due to the widely-distributed Precambrian rocks.Also,it hosts ...The Yili Block in the Western Tianshan orogen is a key area for understanding the early crustal formation and evolution of the Central Asian orogenic belt,due to the widely-distributed Precambrian rocks.Also,it hosts a lot of medium–to large-scale sedimentary exhalative(SEDEX)Pb-Zn deposits that mainly occur in Proterozoic metamorphosed clasticcarbonate rocks.In this study,LA-ICP-MS U-Pb analyses were carried out on detrital zircons in siltstones of the Precambrian Haerdaban Group in the Haerdaban Pb-Zn deposit and magmatic zircons in the diorite dyke that cuts through the strata and orebodies.The maximum depositional age of the siltstones was determined to be about 604 Ma,the diorite having formed at approximately 500 Ma.As such,the Haerdaban Group was most likely formed in the Neoproterozoic Sinian,rather than the previously considered Mesoproterozoic Changchengian.Detrital materials of the Haerdaban Group were mostly derived from the Nanhua–Sinian mafic dykes and granitic rocks around Lake Sayram at the northern margin of the Yili Block.It is proposed that the Yili Block,together with the Kazakhstan and Central Tianshan blocks and the Tarim Craton,might all pertain to the same Rodinia supercontinent,which has great potential for targeting large to super-large SEDEX Pb-Zn deposits.展开更多
22 typical test points and 8 profiles were selected and arranged in the plain of Yili River Valley based on lithological distribution and sedimentary characteristics to study spatial variability of soil infiltration c...22 typical test points and 8 profiles were selected and arranged in the plain of Yili River Valley based on lithological distribution and sedimentary characteristics to study spatial variability of soil infiltration coefficient. The results show that the infiltration coefficient of different geo-morphic units is as follows: the desert area > the pre-mountain alluvial-proluvial plain > river terrace,which is mainly related to the lithology of aeration zone,buried depth of groundwater and underlying surface. For the infiltration coefficient of different aeration zone mediums,the results are consistent with the changing law. The partition of plain of the Yili River Valley is based on geo-morphic units,infiltration coefficient and the lithology of aeration zone. The maximum infiltration coefficient is concentrated in the desert area,and there is zonal distribution of infiltration coefficient in plane.展开更多
The climate is influenced by westerlies year in year out and the aeolian loess is widespread in the Yili region, the Xinjiang Uygur Autonomous Region. Through the study of the loess section with a thickness of 21.5 m,...The climate is influenced by westerlies year in year out and the aeolian loess is widespread in the Yili region, the Xinjiang Uygur Autonomous Region. Through the study of the loess section with a thickness of 21.5 m, much useful information about climatic change in this region during the last glaciation was gotten. Grain size analysis of loess samples in the section showed that the climatic change in the Yili region was of instability during the last glaciation and similar to those of the North Atlantic Ocean and Greenland. In correspondence with the Heinrich events, the percentage of the size fraction of loess with grain size less than 10 μm decreased in cold stadials in the Yili region. This result suggests that the westerly wind be strengthened during the cold periods. Compared with the stadials, the content of the loess with grain size less than 10 μm was increased in interstadials, which indicated that the strength of the westerly wind was weakened. It is obvious that the climate was instable展开更多
To study the historical temperature variation in Yili of Xinjiang,the tree-ring chronologies of maximum density(MXD)and tree-ring width(TRW)were established with the Schrenk Spruce(Picea schrenkiana Fisch.et Mey)colle...To study the historical temperature variation in Yili of Xinjiang,the tree-ring chronologies of maximum density(MXD)and tree-ring width(TRW)were established with the Schrenk Spruce(Picea schrenkiana Fisch.et Mey)collected from six sites to analyze the characteristics and ability of response to climate change.The results suggest that the MXD chronology of the Schrenk Spruce from different sampling sites responded to climate change well and were positively correlated with the mean maximum temperature and the mean temperature from April to August in the study area.The mean maximum temperature anomaly from April to August,spanning the years from 1848 to 2000,was reconstructed by three MXD chronologies which were selected by stepwise regression.The reconstructed function was stable and explained 56.2%of the variance.The reconstructed results indicated a cold span of 153 years in spring and summer from the beginning of the 1950s to the beginning of the 1970s in the Yili valley.No strongly increasing tendency was detected in the mean maximum temperature anomaly from April to August during this reconstructed period.展开更多
Due to the influence of cloud and saturated waveforms, ICESat data contain many contaminated elevation data that cannot be directly used in examining surface elevation and change. This study provides a novel solution ...Due to the influence of cloud and saturated waveforms, ICESat data contain many contaminated elevation data that cannot be directly used in examining surface elevation and change. This study provides a novel solution for removing bad data and getting clean ICESat data for land applications by using threshold values of reflectivity, saturation, and gain directly from ICESat＇s GLAS （Geoscience Laser Alteimeter System） 01, 05, and 06 products. It is found that each laser campaign needs different threshold compositions to assure qualified ICESat data and that bad data removal rates range from 9.6% （laser 2A） to 62.3% （laser 2B） for the test area in the Yili watershed, China. These thresholds would possibly be used in other regions to extract qualified ICESat footprints for land applications. However, it is recommended to use the steps proposed here to further examine the transferability of threshold values for other regions of different elevations and climate regimes. As an example, the resulting ICESat data are applied to examine lake level changes of two lakes in the study area.展开更多
基金Under the auspices of the Third Xinjiang Scientific Expedition Program(No.2022xjkk0600)。
文摘The Yili River Basin in Northwest China is a crucial ecological security barrier,yet it faces frequent droughts amid global climate change,posing significant threats to food security and ecological stability.However,the spatiotemporal variations and driving mechanisms of drought in the basin remain unclear.Based on the monthly Standardized Precipitation Evapotranspiration Index(SPEI),this study employed the Run-Length theory to identify drought events in the basin during 1980-2020,applied statistical and time-series analyses to investigate the spatiotemporal variations,trends,periodicity,and persistence of drought,and explored the underlying drivers associated with meteorological factors and large-scale atmospheric circulation patterns.The results showed that droughts in the Yili River Basin are more severe in spring and summer.Droughts in the central and southwestern regions exhibit greater severity,with shorter durations and stronger intensity.Drought conditions have generally worsened(Sen’s slope=−0.146/10 yr),with notable intensification since 2005,especially in the northwestern region.Spring droughts(Sen’s slope=−0.213/10 yr)and summer droughts(Sen’s slope=−0.169/10 yr)have intensified at most stations,while autumn and winter droughts have eased.In the future,droughts are expected to alleviate overall,but summer droughts may continue to intensify.The Yili River Basin exhibits two primary drought periods of 9 yr and 21 yr,with primary periods in autumn(20 yr)and winter(20 yr)being longer than those in spring(10 yr)and summer(17 yr).Finally,droughts are impacted by both meteorological factors and large-scale atmospheric circulation patterns.Rising temperatures and uneven precipitation have intensified droughts.The SPEI exhibits a co-phase relationship with the North Atlantic Oscillation and an antiphase relationship with the East Central Tropical Pacific Sea Surface Temperature.Therefore,close monitoring and mitigation are necessary for spring and summer droughts,with a focus on the central and southwestern areas in autumn and winter.
文摘As the first national exhibition with the theme of supply chain,China International Supply Chain Expo(hereinafter referred to as the CISCE)has already become a key spot to observe the establishment of the Chinese enterprise industry chain.During the evolution of three CISCE,the leading dairy enterprise,Yili Group(hereinafter referred to as Yili),takes the practice of the entire industry chain as a sample,clearly outlining the development trajectory of China's dairy industry from“following”to“leading”.Its explorations of indust r ial chain col laborat ion,green transformation,and global layout are prominent.Therefore,providing a good paradigm for the high-quality development of the real economy.
基金This research is financially supported by China Geological Survey project“Comprehensive Monitoring of Resources and Environment Bearing Capacity and Digital Platform Construction of Xiongan New Area”(121201003000172401)“Aero Geophysical Survey of Qinling and Tianshan metallogenetic belt”(121201003000150006).
文摘Gold,iron,copper,lead-zinc and other mineral exploration in West Tianshan,Xinjiang Uygur Autonomous Region,has made remarkable progress in recent years.However,due to the dispute on the tectonic division of West Tianshan,the ore-controlling factors and the regional metallogenic laws are controversial.The authors analyze regional gravity data and notice that the high-value region corresponds to the Yili ancient continent,thus the southeastern boundary of the Yili ancient continent is delineated.Comparative analysis of gravity,aeromagnetic and geologic data reveals that the Tulasu basin,where some medium to large epithermal gold deposits locate,lies above the Yili ancient continent;the Yili Carboniferous-Permian rift extends in E-W direction,numbers of copper deposits have been found in the mid-west section of the rift which lies above the Yili ancient continent,whereas few copper deposits have been discovered in the east section which is outside the Yili ancient continent.Accordingly,the Yili ancient continent may be rich in gold,copper and other metal elements;the metal-bearing hydrothermal solution moves up with the activity of magmatism,and deposits in the favorable places(the Tulasu basin and the Yili Carboniferous-Permian rift),forming numerous small and medium gold,copper deposits,as well as some large and super-large gold deposits.Therefore,the tectonic-magmatic hydrothermal zone above the Yili ancient continent should be the prospective area for epithermal gold and copper polymetallic deposits.
基金Knowledge Innovation Project of CAS No. KZCX02-308
文摘With the development of Internet technologies, Internet Based Information System (IBIS) arises with more advantages: Firstly, it is convenient for users to use owing to the introduction of Internet technologies. Secondly, it benefits greatly the data dissemination and data sharing based on Internet. The most important but not the last is that we can establish the information service network supported by its technologies and the facilities of information highway. So, it would be significant to design IBIS to realize the data collection, sharing and dissemination on Internet. There are many factors affecting regional environment. So it is not easy to realize the integrated environmental monitoring. Given this, we designed the Internet based environmental monitoring information system. By the virtue of the Internet based environmental monitoring information system, the management and storage of environmental monitoring data would be easier, which lays the foundation to actualize the environmental monitoring efficiently.
基金in part supported by the National Natural Science Foundation of China(Nos.41572316,41102131)the Guangdong Natural Science Foundation(No.2015A030313193)
文摘Bedding orientation measurement is a remote sensing application used in the field of geology, but the results are often unsatisfactory when the bed is dislocated along the strike direction. This paper proposes a new method called multiple-line method that is designed to improve bedding orientation measurement. This technique uses the bed as a vector, and fits the vectors as a plane to obtain the bedding orientation. This study employs the case of Yili Basin and measures 25 bedding orientations using the multiple-point and multiple-line methods, respectively. The result shows that the errors from the multiple-line method are mostly smaller than those from the multiple-point method when a bed is discontinuous.
基金financial support of the Natural Science Foundation of China (No. 41772200)China Earthquake Administration teacher research Fund (No. 20140103)+1 种基金China Geological Survey Program (No. 121201011000150021, No.DD20190351)Innovation Leading Talents Program of Qingdao (19–3–2–19–zhc)
文摘The Quaternary sediments in the Yili Basin can serve as archives for studying the Cenozoic basin-mountain relationship. In this study, based on typical natural sections and boreholes, the surficial sediments of the Huocheng area were studied, and their sedimentary ages were obtained using the optically stimulated luminescence(OSL) and electron spin resonance(ESR) dating methods. These dates, combined with changes in the sedimentary facies, provided details of the neotectonic movement in the Yili Basin and adjacent areas. By dating sediments from five sections and three boreholes, we determined that the surficial sediments of the Huocheng area were mainly formed in the Late Pleistocene, with scattered instances of Holocene sediments. The surficial sediments mainly consisted of alluvial fan facies, fluvial facies, lacustrine facies, and desert facies. Based on the activity on the Hongshanzui fault and the northern margin fault of the Wusun Mountains, the Huocheng area was uplifted synchronously with the Tianshan Mountains during the last stage of the Late Pleistocene, causing the desert facies sediments to be superimposed on the former paleo-lake sediments.
基金Under the auspices of National Natural Science Foundation of China (No. 41001108, 41071065)Beijing Municipal Natural Science Foundation (No. 9113029)
文摘In developing countries, land productivity involves little market, where the agricultural land use is mainly determined by the food demands as well as the land suitability. The land use pattern will not ensure everywhere enough land for certain cropping if spatial allocation just according to land use suitability. To solve this problem, a subzone and a pre-allocation for each land use are added in spatial allocation module, and land use suitability and area optimi- zation module are incorporated to constitute a whole agricultural land use optimal allocation （ALUOA） system. The system is developed on the platform .Net 2005 using ArcGIS Engine （version 9.2） and C# language, and is tested and validated in Yili watershed of Xinjiang Region on the newly reclaimed area. In the case study, with the help of soil data obtained from 69 points sampled in the fieldwork in 2008, main river data supplied by the Department of Water Resources of Xinjiang Uygur Autonomous Region in China, and temperature data provided by Data Center for Resources and Environmental Sciences, Chinese Academy of Sciences, land use suitability on eight common crops are evaluated one by one using linear weighted summation method in the land use suitability model. The linear pro- gramming （LP） model in area optimization model succeeds to give out land area target of each crop under three scenarios. At last, the land use targets are allotted in space both with a six subzone file and without a subzone file. The resuits show that the land use maps with a subzone not only ensure every part has enough land for every crop, but also gives a more fragmental land use pattern, with about 87.99% and 135.92% more patches than the one without, while at the expense of loss between 15.30% and 19.53% in the overall suitability at the same time.
基金funded by the Key Project of the National Natural Science Foundation of China(Grant No.42130804)the National Key R&D Program of China(Grant No.2018YFC0604003)+1 种基金the Fundamental Research Funds for the Central Universities(Grant No.35942019012)the State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences(Grant No.MSFGPMR201810)。
文摘The Yili Block in the Western Tianshan orogen is a key area for understanding the early crustal formation and evolution of the Central Asian orogenic belt,due to the widely-distributed Precambrian rocks.Also,it hosts a lot of medium–to large-scale sedimentary exhalative(SEDEX)Pb-Zn deposits that mainly occur in Proterozoic metamorphosed clasticcarbonate rocks.In this study,LA-ICP-MS U-Pb analyses were carried out on detrital zircons in siltstones of the Precambrian Haerdaban Group in the Haerdaban Pb-Zn deposit and magmatic zircons in the diorite dyke that cuts through the strata and orebodies.The maximum depositional age of the siltstones was determined to be about 604 Ma,the diorite having formed at approximately 500 Ma.As such,the Haerdaban Group was most likely formed in the Neoproterozoic Sinian,rather than the previously considered Mesoproterozoic Changchengian.Detrital materials of the Haerdaban Group were mostly derived from the Nanhua–Sinian mafic dykes and granitic rocks around Lake Sayram at the northern margin of the Yili Block.It is proposed that the Yili Block,together with the Kazakhstan and Central Tianshan blocks and the Tarim Craton,might all pertain to the same Rodinia supercontinent,which has great potential for targeting large to super-large SEDEX Pb-Zn deposits.
基金Supported by National Natural Science Foundation of China(41202178,41372260,41472220)Open Foundation for Key Laboratories of Ministry of Education of China(2014G1502024)+1 种基金Project of China Geological Survey(1212011014024)Innovation Capability Support Program of Shaanxi(2019TD-040)。
文摘22 typical test points and 8 profiles were selected and arranged in the plain of Yili River Valley based on lithological distribution and sedimentary characteristics to study spatial variability of soil infiltration coefficient. The results show that the infiltration coefficient of different geo-morphic units is as follows: the desert area > the pre-mountain alluvial-proluvial plain > river terrace,which is mainly related to the lithology of aeration zone,buried depth of groundwater and underlying surface. For the infiltration coefficient of different aeration zone mediums,the results are consistent with the changing law. The partition of plain of the Yili River Valley is based on geo-morphic units,infiltration coefficient and the lithology of aeration zone. The maximum infiltration coefficient is concentrated in the desert area,and there is zonal distribution of infiltration coefficient in plane.
文摘The climate is influenced by westerlies year in year out and the aeolian loess is widespread in the Yili region, the Xinjiang Uygur Autonomous Region. Through the study of the loess section with a thickness of 21.5 m, much useful information about climatic change in this region during the last glaciation was gotten. Grain size analysis of loess samples in the section showed that the climatic change in the Yili region was of instability during the last glaciation and similar to those of the North Atlantic Ocean and Greenland. In correspondence with the Heinrich events, the percentage of the size fraction of loess with grain size less than 10 μm decreased in cold stadials in the Yili region. This result suggests that the westerly wind be strengthened during the cold periods. Compared with the stadials, the content of the loess with grain size less than 10 μm was increased in interstadials, which indicated that the strength of the westerly wind was weakened. It is obvious that the climate was instable
基金Supported by the National Basic Research Program of China(Grant No.2009CB421307)Research Foundation of Chinese Desert Meteorology(Grant No.SQJ2006013)National Natural Science Foundation of China(Grant Nos.30270227 and J0630965)
文摘To study the historical temperature variation in Yili of Xinjiang,the tree-ring chronologies of maximum density(MXD)and tree-ring width(TRW)were established with the Schrenk Spruce(Picea schrenkiana Fisch.et Mey)collected from six sites to analyze the characteristics and ability of response to climate change.The results suggest that the MXD chronology of the Schrenk Spruce from different sampling sites responded to climate change well and were positively correlated with the mean maximum temperature and the mean temperature from April to August in the study area.The mean maximum temperature anomaly from April to August,spanning the years from 1848 to 2000,was reconstructed by three MXD chronologies which were selected by stepwise regression.The reconstructed function was stable and explained 56.2%of the variance.The reconstructed results indicated a cold span of 153 years in spring and summer from the beginning of the 1950s to the beginning of the 1970s in the Yili valley.No strongly increasing tendency was detected in the mean maximum temperature anomaly from April to August during this reconstructed period.
基金We thank NASA＇s ICESat Science Project and the NSIDC for distribution of the ICESat data. This work was in part supported by the National Natural Science Foundation of China （Grant Nos. 41101337 and 31228021 ） and the Cultivation Fund of the Key Scientific and Technical Innovation Project, Ministry of Education of China （No. 708089）. Authors want to thank Donghui Yi （NASA/Goddard） for helpful discussion on the early stage of the study and Ning Lv （IGSNRR/CAS） for help in developing the IDL code when he was a visiting scholar at UTSA.
文摘Due to the influence of cloud and saturated waveforms, ICESat data contain many contaminated elevation data that cannot be directly used in examining surface elevation and change. This study provides a novel solution for removing bad data and getting clean ICESat data for land applications by using threshold values of reflectivity, saturation, and gain directly from ICESat＇s GLAS （Geoscience Laser Alteimeter System） 01, 05, and 06 products. It is found that each laser campaign needs different threshold compositions to assure qualified ICESat data and that bad data removal rates range from 9.6% （laser 2A） to 62.3% （laser 2B） for the test area in the Yili watershed, China. These thresholds would possibly be used in other regions to extract qualified ICESat footprints for land applications. However, it is recommended to use the steps proposed here to further examine the transferability of threshold values for other regions of different elevations and climate regimes. As an example, the resulting ICESat data are applied to examine lake level changes of two lakes in the study area.
