The simulation of hydrological consequences of climate change has received increasing attention from the hydrology and land-surface modelling communities. There have been many studies of climate-change effects on hydr...The simulation of hydrological consequences of climate change has received increasing attention from the hydrology and land-surface modelling communities. There have been many studies of climate-change effects on hydrology and water resources which usually consist of three steps： （1） use of general circulation models （GCMs） to provide future global climate scenarios under the effect of increasing greenhouse gases, （2） use of downscaling techniques （both nested regional climate models, RCMs, and statistical methods） for ＂downscaling＂ the GCM output to the scales compatible with hydrological models, and （3） use of hydrologic models to simulate the effects of climate change on hydrological regimes at various scales. Great progress has been achieved in all three steps during the past few years, however, large uncertainties still exist in every stage of such study. This paper first reviews the present achievements in this field and then discusses the challenges for future studies of the hydrological impacts of climate change.展开更多
Hydrological and LADCP data from four experiments at sea (Semane 1999, 2000/1 2000/3, 2001) are used to describe the structure and circulation of Mediterranean Water in the Gulf of Cadiz. These data were gathered on m...Hydrological and LADCP data from four experiments at sea (Semane 1999, 2000/1 2000/3, 2001) are used to describe the structure and circulation of Mediterranean Water in the Gulf of Cadiz. These data were gathered on meridional sections along 8?20′W and 6?15′W and between these longitudes on a zonal section along 35?50′N. The mesoscale and the submesoscale structures (Mediterranean Water Undercurrents, meddies, cyclones) observed along these sections are characterized in terms of thermohaline properties and of velocity. The transports of mass and salt in each class of density (North Atlantic Central Water, Mediterranean Water, North Atlantic Deep Water) are computed with an inverse model. The model indicates a general eastward flux in the Central Water layer, and a westward flux in the Mediterranean Water layer, but there is also a horizontal recirculation and entrainment in these two layers, as well as strong transports associated with the meddy and cyclone found during Semane 1999.展开更多
The oxidation rate,the growth,morphology and structure of oxide scale and whiskers for Fe-Ni-Cr sealing alloys in H_2-H_2O atmosphere at high temperatures have been studied. The growth rate of scale is controlled by d...The oxidation rate,the growth,morphology and structure of oxide scale and whiskers for Fe-Ni-Cr sealing alloys in H_2-H_2O atmosphere at high temperatures have been studied. The growth rate of scale is controlled by diffusion.The scale is composed of Cr_2O_3 and spinel(Fe,Mn)O·Cr_2O_3 and the oxide whisker,are spinel(Fe,Mn)O·Cr_2O_3.展开更多
Lakes have received considerable attention as long-term sinks for organic carbon(C)at regional and global scales.Previ ous studies have focused on assessment and quantification of carbon sinks,and few have worked on t...Lakes have received considerable attention as long-term sinks for organic carbon(C)at regional and global scales.Previ ous studies have focused on assessment and quantification of carbon sinks,and few have worked on the relationship be tween millennial-scale lake C sequestration,hydrological status and vegetation,which has important scientific signifi cance in improving our understanding of lake C stocks and storage mechanisms.Here,we present a comprehensive study of pollen records,organic geochemical proxies,lake-level records,sediment accumulation rate(SAR)and organic C accu mulation rate(CAR)in China since the Holocene.We also include numerical climate classification and lake-level simula tions,to investigate variations of lake C sequestration,hydrological status and vegetation during the Holocene.Results in dicate that the evolution of lake C accumulation showed an out-of-phase relationship with hydrological status and vegeta tion in China.Lake C accumulation exhibited an overall trend of increasing from the early to late Holocene in response to gradually increasing terrestrial organic matter input.However,China as a whole experienced the densest vegetation cover in the middle Holocene,corresponding to the mid-Holocene optimum of a milder and wetter climate.Optimal hydrologi cal conditions were asynchronous in China;for example,early Holocene in Asian monsoon dominated areas,and middle Holocene in westerlies controlled regions.Our synthesis indicated that climate change was the main factor controlling the long-term variability in lake C accumulation,hydrologic conditions,as well as vegetation,and human influences were usu ally superimposed on the natural trends.展开更多
湿地内的水文连通对维持湿地生态系统的完整性具有重要意义。本文以Google Eearth Engine为平台支撑,在全局尺度上利用水体面积、水文连通CFV指数(Connectivity Function Value)、像元月均淹没频率对1986—2020年黄河三角洲湿地水文连...湿地内的水文连通对维持湿地生态系统的完整性具有重要意义。本文以Google Eearth Engine为平台支撑,在全局尺度上利用水体面积、水文连通CFV指数(Connectivity Function Value)、像元月均淹没频率对1986—2020年黄河三角洲湿地水文连通进行定量分析,并利用灰色关联法进行驱动力分析;在淡咸水交互的典型区域尺度上选择水文环度(α指数)、节点连接率(β指数)、水文连通性(γ指数)进行区域水文连通定量分析。结果表明:(1)湿地水体面积整体增加,水文连通CFV指数减少,研究区内发生了连通阻断,重度淹没和永久性淹没主要集中在浅海区域;(2)湿地水体面积和水文连通CFV指数均呈季节性差异,自然因素对水文连通影响大于人类活动。黄河三角洲湿地水文连通性30余年一直保持中等水平。研究结果可为黄河三角洲湿地水文连通保护与修复提供参考。展开更多
文摘The simulation of hydrological consequences of climate change has received increasing attention from the hydrology and land-surface modelling communities. There have been many studies of climate-change effects on hydrology and water resources which usually consist of three steps： （1） use of general circulation models （GCMs） to provide future global climate scenarios under the effect of increasing greenhouse gases, （2） use of downscaling techniques （both nested regional climate models, RCMs, and statistical methods） for ＂downscaling＂ the GCM output to the scales compatible with hydrological models, and （3） use of hydrologic models to simulate the effects of climate change on hydrological regimes at various scales. Great progress has been achieved in all three steps during the past few years, however, large uncertainties still exist in every stage of such study. This paper first reviews the present achievements in this field and then discusses the challenges for future studies of the hydrological impacts of climate change.
文摘Hydrological and LADCP data from four experiments at sea (Semane 1999, 2000/1 2000/3, 2001) are used to describe the structure and circulation of Mediterranean Water in the Gulf of Cadiz. These data were gathered on meridional sections along 8?20′W and 6?15′W and between these longitudes on a zonal section along 35?50′N. The mesoscale and the submesoscale structures (Mediterranean Water Undercurrents, meddies, cyclones) observed along these sections are characterized in terms of thermohaline properties and of velocity. The transports of mass and salt in each class of density (North Atlantic Central Water, Mediterranean Water, North Atlantic Deep Water) are computed with an inverse model. The model indicates a general eastward flux in the Central Water layer, and a westward flux in the Mediterranean Water layer, but there is also a horizontal recirculation and entrainment in these two layers, as well as strong transports associated with the meddy and cyclone found during Semane 1999.
文摘The oxidation rate,the growth,morphology and structure of oxide scale and whiskers for Fe-Ni-Cr sealing alloys in H_2-H_2O atmosphere at high temperatures have been studied. The growth rate of scale is controlled by diffusion.The scale is composed of Cr_2O_3 and spinel(Fe,Mn)O·Cr_2O_3 and the oxide whisker,are spinel(Fe,Mn)O·Cr_2O_3.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41822708 and 41571178)the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDA20100102)+1 种基金the Fundamental Research Funds for the Central Universities (Grant No. lzujbky-2018-k15)the Second Tibetan Plateau Scientific Expedition (STEP) program (Grant No. XDA20060700)
文摘Lakes have received considerable attention as long-term sinks for organic carbon(C)at regional and global scales.Previ ous studies have focused on assessment and quantification of carbon sinks,and few have worked on the relationship be tween millennial-scale lake C sequestration,hydrological status and vegetation,which has important scientific signifi cance in improving our understanding of lake C stocks and storage mechanisms.Here,we present a comprehensive study of pollen records,organic geochemical proxies,lake-level records,sediment accumulation rate(SAR)and organic C accu mulation rate(CAR)in China since the Holocene.We also include numerical climate classification and lake-level simula tions,to investigate variations of lake C sequestration,hydrological status and vegetation during the Holocene.Results in dicate that the evolution of lake C accumulation showed an out-of-phase relationship with hydrological status and vegeta tion in China.Lake C accumulation exhibited an overall trend of increasing from the early to late Holocene in response to gradually increasing terrestrial organic matter input.However,China as a whole experienced the densest vegetation cover in the middle Holocene,corresponding to the mid-Holocene optimum of a milder and wetter climate.Optimal hydrologi cal conditions were asynchronous in China;for example,early Holocene in Asian monsoon dominated areas,and middle Holocene in westerlies controlled regions.Our synthesis indicated that climate change was the main factor controlling the long-term variability in lake C accumulation,hydrologic conditions,as well as vegetation,and human influences were usu ally superimposed on the natural trends.
文摘湿地内的水文连通对维持湿地生态系统的完整性具有重要意义。本文以Google Eearth Engine为平台支撑,在全局尺度上利用水体面积、水文连通CFV指数(Connectivity Function Value)、像元月均淹没频率对1986—2020年黄河三角洲湿地水文连通进行定量分析,并利用灰色关联法进行驱动力分析;在淡咸水交互的典型区域尺度上选择水文环度(α指数)、节点连接率(β指数)、水文连通性(γ指数)进行区域水文连通定量分析。结果表明:(1)湿地水体面积整体增加,水文连通CFV指数减少,研究区内发生了连通阻断,重度淹没和永久性淹没主要集中在浅海区域;(2)湿地水体面积和水文连通CFV指数均呈季节性差异,自然因素对水文连通影响大于人类活动。黄河三角洲湿地水文连通性30余年一直保持中等水平。研究结果可为黄河三角洲湿地水文连通保护与修复提供参考。
