以杂萘联苯聚芳醚腈为研究对象,分别采用多种良溶剂和不良溶剂进行浊度滴定实验,由KY(Kumar and Yildirim)一阶算法对其产生的25个浊点数据进行最小体积闭包椭球拟合,从而确定椭球球心为三维溶解度参数(δd=17.50(MPa)1/2;δp=11.19(MPa...以杂萘联苯聚芳醚腈为研究对象,分别采用多种良溶剂和不良溶剂进行浊度滴定实验,由KY(Kumar and Yildirim)一阶算法对其产生的25个浊点数据进行最小体积闭包椭球拟合,从而确定椭球球心为三维溶解度参数(δd=17.50(MPa)1/2;δp=11.19(MPa)1/2;δH=10.96(MPa)1/2),椭球包围的区域为聚合物的溶解区域。采用THF作为鉴别溶剂,判定该拟合结果精确可靠。三维溶解度参数方法操作简便,计算简单、选用溶剂少,对聚合物溶剂的选择具有重要的指导意义。展开更多
Quantitatively estimating the global mean precipitation(GMP)throughout Earth's history is crucial for enhancing our understanding of long-term climate evolution and the hydrological cycle.However,currently there i...Quantitatively estimating the global mean precipitation(GMP)throughout Earth's history is crucial for enhancing our understanding of long-term climate evolution and the hydrological cycle.However,currently there is no established methodology for estimating global mean paleoprecipitation.Here,we present the first study that estimates GMP in the Phanerozoic era.The relationship between GMP and global mean surface temperature(GMST)is investigated by analyzing data from 23 models in the Coupled Model Intercomparison Project phase 6(CMIP6).The result reveals consistent and significant impact of temperature on precipitation,with a sensitivity range of 2–3%K^(-1).Additionally,we propose a method for accessing latitudinal variations in precipitation caused by land area distributions and paleo-Koppen climatic belts.These climatic belts are determined based on geological indicators such as coals,evaporites,and glacial deposits.The GMP is thus quantitatively estimated by combining variations in GMST,land area distributions,and paleo-koppen climatic belts,spanning from 540 Ma to the present day.The quantitative GMP curve demonstrates fluctuations in GMP about 500 mm yr^(-1),with values ranging from 948 to1442 mm yr-1over the Phanerozoic era.This curve aligns closely with findings derived from numerical simulations.The presented paleoprecipitation variations facilitate a more comprehensive understanding of the interconnected geological and paleoclimatic developments.展开更多
Recent studies showed that the Himalayan glaciers are reducing alarmingly. This is attributed to global warming. Since the melt water of Himalayan glaciers and snow is the principal source of water for several rivers,...Recent studies showed that the Himalayan glaciers are reducing alarmingly. This is attributed to global warming. Since the melt water of Himalayan glaciers and snow is the principal source of water for several rivers, a decrease of this source is a calamity for the large fraction of global population living in nearby regions such as India. In Asia for the 60% global population only 36% of global water is available. Any further decrease of this vital necessity makes the very existence of billions of people doubtful. Here we show, using both observations and one IPCC-AR4 model with high horizontal resolution, that the Himalayan region in fact underwent a maximum warming of 2.5°C from 1950 to 1999 and would reach the highest temperature rise of 9°C in 2100. Temperature and rainfall variations determine a simple climate classification proposed by Köppen. We show changes that occur in climate and biosphere using this classification. Also we discussed the impact of warming and resulting changes in Köppen climates on the floods and malaria in India.展开更多
Mid-high latitude Northern Asia is one of the most vulnerable and sensitive areas to global warming,but relatively less studied previously.We used an ensemble of a regional climate model(RegCM4)projections to assess f...Mid-high latitude Northern Asia is one of the most vulnerable and sensitive areas to global warming,but relatively less studied previously.We used an ensemble of a regional climate model(RegCM4)projections to assess future changes in surface air temperature,precipitation and Köppen-Trewartha(K-T)climate types in Northern Asia under the 1.5-4℃global warming targets.RegCM4 is driven by five CMIP5 global models over an East Asia domain at a grid spacing of 25 km.Validation of the present day(1986-2005)simulations shows that the ensembles of RegCM4(ensR)and driving GCMs(ensG)reproduce the major characters of the observed temperature,precipitation and K-T climate zones reasonably well.Greater and more realistic spatial detail is found in RegCM4 compared to the driving GCMs.A general warming and overall increases in precipitation are projected over the region,with these changes being more pronounced at higher warming levels.The projected warming by ensR shows different spatial patterns,and is in general lower,compared to ensG in most months of the year,while the percentage increases of precipitation are maximum during the cold months.The future changes in K-T climate zones are characterized by a substantial expansion of Dc(temperature oceanic)and retreat of Ec(sub-arctic continental)over the region,reaching∼20%under the 4℃warming level.The most notable change in climate types in ensR is found over Japan(∼60%),followed by Southern Siberia,Mongolia,and the Korean Peninsula(∼40%).The largest change in the K-T climate types is found when increasing from 2 to 3℃.The results will help to better assess the impacts of climate change and in implementation of appropriate adaptation measures over the region.展开更多
The aim of this pilot study conducted by the consortium for capacity building was to develop a prototype concept and methodology for the classification and visualization of the geographic impacts of El Nio on annual...The aim of this pilot study conducted by the consortium for capacity building was to develop a prototype concept and methodology for the classification and visualization of the geographic impacts of El Nio on annual climates and seasonality. Our study is based on the Kppen–Geiger climate classification scheme for a set of selected countries affected by strong El Nios in Latin America. By identifying and visualizing the annual and seasonal changes in regional, national, or subnational climate regimes that generally accompany an El Nio event,this research proposes an efficient way to detect and describe climate shifts and variability across time and space. Such knowledge provides a support tool for risk analysis and can potentially enhance government efforts of climate risk management, including disaster risk reduction activities that prevent, mitigate, and improve coping responses to El Nio-related hydrometeorological threats.Details of the conceptual approach and methodology to classifying and mapping El Nio's impacts are described and explained using the Central American and circumCaribbean region as a case study. The potential applications for disaster risk reduction as well as its limitations and future work are also discussed.展开更多
土壤剖面水分信息比表层土壤水分信息难以获取,但对全面认识整个土层的水分含量至关重要。融合多源数据是估算区域土壤剖面水分的有效途径。本文采用随机森林回归算法,利用中国实测土壤水分数据建立了不同季节的表层-深层土壤水分关系...土壤剖面水分信息比表层土壤水分信息难以获取,但对全面认识整个土层的水分含量至关重要。融合多源数据是估算区域土壤剖面水分的有效途径。本文采用随机森林回归算法,利用中国实测土壤水分数据建立了不同季节的表层-深层土壤水分关系模型。据此采用ESA CCI SM遥感表层土壤水分产品估算获得了中国1980—2019年0~10、0~20、0~30、0~40、0~50、0~60、0~70、0~80、0~90和0~100 cm共10个深度层次土壤水分的时空变化特征。ESA CCI SM产品与实测数据整体上匹配较好但普遍高估,本文提出采用饱和含水量和凋萎系数信息对其进行值域控制,有效降低了该产品的高估误差。随机森林回归模型的精度在秋季最高,夏季和春季次之,冬季最低。模型对干带土壤水分的估算最准确,暖温带和冷温带次之,青藏带准确性最低。计算了中国10个深度层次的土壤贮水量,其多年平均值和标准差分别为1.64±0.11、3.50±0.21、5.29±0.30、7.13±0.38、10.04±0.46、12.25±0.54、14.47±0.62、16.75±0.69、19.05±0.76和21.36±0.83 cm。各深度的土壤水分呈明显的分层,即波动层(0~40 cm)、跃变层(40~60cm)和稳定层(60~100 cm)。中国1m土层贮水量呈自西北向东北和东南方向递增的分布格局,寒旱区该值较低且空间变异明显,暖湿区该值较高且空间分布更均一。热带、干带和青藏带的1 m土层贮水量在夏季最高,暖温带和冷温带该值在夏季最低。近40年来中国1m土层贮水量在空间上“湿区愈湿,干区愈干”,在时间上“湿季愈湿,干季愈干”。热带土壤在2004—2009年显著变湿,干带土壤显著变湿和变干的转折年份分别为1985—1986年和2013—2014年。中国1m土层贮水量序列最常见的周期是5年和11年。展开更多
通过对PLo S One进行简要介绍,分析了有关PLo S One发文量、影响因子、出版周期、稿件录用、出版费、审稿等情况,以及PLo S One对论文的要求、对审稿人的要求、学术评价方式,指出PLo S One从多个方面突破了传统出版模式的障碍,创造出了...通过对PLo S One进行简要介绍,分析了有关PLo S One发文量、影响因子、出版周期、稿件录用、出版费、审稿等情况,以及PLo S One对论文的要求、对审稿人的要求、学术评价方式,指出PLo S One从多个方面突破了传统出版模式的障碍,创造出了开放获取学术出版的新方式,促进了科学研究的快速交流。展开更多
文摘以杂萘联苯聚芳醚腈为研究对象,分别采用多种良溶剂和不良溶剂进行浊度滴定实验,由KY(Kumar and Yildirim)一阶算法对其产生的25个浊点数据进行最小体积闭包椭球拟合,从而确定椭球球心为三维溶解度参数(δd=17.50(MPa)1/2;δp=11.19(MPa)1/2;δH=10.96(MPa)1/2),椭球包围的区域为聚合物的溶解区域。采用THF作为鉴别溶剂,判定该拟合结果精确可靠。三维溶解度参数方法操作简便,计算简单、选用溶剂少,对聚合物溶剂的选择具有重要的指导意义。
基金supported by the National Natural Science Foundation of China(Grant No.41888101)the China Postdoctoral Science Foundation(Grant No.2023T160005)。
文摘Quantitatively estimating the global mean precipitation(GMP)throughout Earth's history is crucial for enhancing our understanding of long-term climate evolution and the hydrological cycle.However,currently there is no established methodology for estimating global mean paleoprecipitation.Here,we present the first study that estimates GMP in the Phanerozoic era.The relationship between GMP and global mean surface temperature(GMST)is investigated by analyzing data from 23 models in the Coupled Model Intercomparison Project phase 6(CMIP6).The result reveals consistent and significant impact of temperature on precipitation,with a sensitivity range of 2–3%K^(-1).Additionally,we propose a method for accessing latitudinal variations in precipitation caused by land area distributions and paleo-Koppen climatic belts.These climatic belts are determined based on geological indicators such as coals,evaporites,and glacial deposits.The GMP is thus quantitatively estimated by combining variations in GMST,land area distributions,and paleo-koppen climatic belts,spanning from 540 Ma to the present day.The quantitative GMP curve demonstrates fluctuations in GMP about 500 mm yr^(-1),with values ranging from 948 to1442 mm yr-1over the Phanerozoic era.This curve aligns closely with findings derived from numerical simulations.The presented paleoprecipitation variations facilitate a more comprehensive understanding of the interconnected geological and paleoclimatic developments.
文摘Recent studies showed that the Himalayan glaciers are reducing alarmingly. This is attributed to global warming. Since the melt water of Himalayan glaciers and snow is the principal source of water for several rivers, a decrease of this source is a calamity for the large fraction of global population living in nearby regions such as India. In Asia for the 60% global population only 36% of global water is available. Any further decrease of this vital necessity makes the very existence of billions of people doubtful. Here we show, using both observations and one IPCC-AR4 model with high horizontal resolution, that the Himalayan region in fact underwent a maximum warming of 2.5°C from 1950 to 1999 and would reach the highest temperature rise of 9°C in 2100. Temperature and rainfall variations determine a simple climate classification proposed by Köppen. We show changes that occur in climate and biosphere using this classification. Also we discussed the impact of warming and resulting changes in Köppen climates on the floods and malaria in India.
基金This research was jointly supported by the National Natural Science Foundation of China(41991284)the Science and Technology Project of Education Department of Jiangxi province(GJJ2201249).
文摘Mid-high latitude Northern Asia is one of the most vulnerable and sensitive areas to global warming,but relatively less studied previously.We used an ensemble of a regional climate model(RegCM4)projections to assess future changes in surface air temperature,precipitation and Köppen-Trewartha(K-T)climate types in Northern Asia under the 1.5-4℃global warming targets.RegCM4 is driven by five CMIP5 global models over an East Asia domain at a grid spacing of 25 km.Validation of the present day(1986-2005)simulations shows that the ensembles of RegCM4(ensR)and driving GCMs(ensG)reproduce the major characters of the observed temperature,precipitation and K-T climate zones reasonably well.Greater and more realistic spatial detail is found in RegCM4 compared to the driving GCMs.A general warming and overall increases in precipitation are projected over the region,with these changes being more pronounced at higher warming levels.The projected warming by ensR shows different spatial patterns,and is in general lower,compared to ensG in most months of the year,while the percentage increases of precipitation are maximum during the cold months.The future changes in K-T climate zones are characterized by a substantial expansion of Dc(temperature oceanic)and retreat of Ec(sub-arctic continental)over the region,reaching∼20%under the 4℃warming level.The most notable change in climate types in ensR is found over Japan(∼60%),followed by Southern Siberia,Mongolia,and the Korean Peninsula(∼40%).The largest change in the K-T climate types is found when increasing from 2 to 3℃.The results will help to better assess the impacts of climate change and in implementation of appropriate adaptation measures over the region.
基金the support provided by the Office of US Foreign Disaster Assistance,Bureau for Democracy,Conflict and Humanitarian Assistance,US Agency for International Development
文摘The aim of this pilot study conducted by the consortium for capacity building was to develop a prototype concept and methodology for the classification and visualization of the geographic impacts of El Nio on annual climates and seasonality. Our study is based on the Kppen–Geiger climate classification scheme for a set of selected countries affected by strong El Nios in Latin America. By identifying and visualizing the annual and seasonal changes in regional, national, or subnational climate regimes that generally accompany an El Nio event,this research proposes an efficient way to detect and describe climate shifts and variability across time and space. Such knowledge provides a support tool for risk analysis and can potentially enhance government efforts of climate risk management, including disaster risk reduction activities that prevent, mitigate, and improve coping responses to El Nio-related hydrometeorological threats.Details of the conceptual approach and methodology to classifying and mapping El Nio's impacts are described and explained using the Central American and circumCaribbean region as a case study. The potential applications for disaster risk reduction as well as its limitations and future work are also discussed.
文摘土壤剖面水分信息比表层土壤水分信息难以获取,但对全面认识整个土层的水分含量至关重要。融合多源数据是估算区域土壤剖面水分的有效途径。本文采用随机森林回归算法,利用中国实测土壤水分数据建立了不同季节的表层-深层土壤水分关系模型。据此采用ESA CCI SM遥感表层土壤水分产品估算获得了中国1980—2019年0~10、0~20、0~30、0~40、0~50、0~60、0~70、0~80、0~90和0~100 cm共10个深度层次土壤水分的时空变化特征。ESA CCI SM产品与实测数据整体上匹配较好但普遍高估,本文提出采用饱和含水量和凋萎系数信息对其进行值域控制,有效降低了该产品的高估误差。随机森林回归模型的精度在秋季最高,夏季和春季次之,冬季最低。模型对干带土壤水分的估算最准确,暖温带和冷温带次之,青藏带准确性最低。计算了中国10个深度层次的土壤贮水量,其多年平均值和标准差分别为1.64±0.11、3.50±0.21、5.29±0.30、7.13±0.38、10.04±0.46、12.25±0.54、14.47±0.62、16.75±0.69、19.05±0.76和21.36±0.83 cm。各深度的土壤水分呈明显的分层,即波动层(0~40 cm)、跃变层(40~60cm)和稳定层(60~100 cm)。中国1m土层贮水量呈自西北向东北和东南方向递增的分布格局,寒旱区该值较低且空间变异明显,暖湿区该值较高且空间分布更均一。热带、干带和青藏带的1 m土层贮水量在夏季最高,暖温带和冷温带该值在夏季最低。近40年来中国1m土层贮水量在空间上“湿区愈湿,干区愈干”,在时间上“湿季愈湿,干季愈干”。热带土壤在2004—2009年显著变湿,干带土壤显著变湿和变干的转折年份分别为1985—1986年和2013—2014年。中国1m土层贮水量序列最常见的周期是5年和11年。
文摘通过对PLo S One进行简要介绍,分析了有关PLo S One发文量、影响因子、出版周期、稿件录用、出版费、审稿等情况,以及PLo S One对论文的要求、对审稿人的要求、学术评价方式,指出PLo S One从多个方面突破了传统出版模式的障碍,创造出了开放获取学术出版的新方式,促进了科学研究的快速交流。
