The structure and function of network is a central issue in landscape ecology.Road networks with hierarchical structure are crucial for understanding landscape dynamics.In this study,we compared the distribution of na...The structure and function of network is a central issue in landscape ecology.Road networks with hierarchical structure are crucial for understanding landscape dynamics.In this study,we compared the distribution of national road,provincial road,county road and rural road in the Three Parallel Rivers Region(TPRR)in Yunnan Province of China,and estimated the effect of roads(and other factors)on the spatial patterns of land use and land cover with logistic regression.In addition,we analyzed the land use and land cover change(LUCC)and landscape fragmentation in 1989–2005 along a buffer zone of the primary traffic corridor,national road G214.The results showed that,county and rural roads had much higher percentage of length extending into more natural habitats at higher elevation and steeper slope,compared with the higher level roads in this region.While the distributions of natural land cover types were dominated by environmental factors,human land use types i.e.,building land and farmland types were significantly related with roads,linking more closely with lower level roads.The LUCC dynamics(1989–2005)of the G214 buffer zone showed a general trend of land transformation from conifer forests and valley arid shrubs to building land and farmland,and from ice and snow to alpine shrubs and forests.With the length of G214 unchanged during the time,the overall landscape pattern changed little in the buffer zone,but habitat fragmentation and area decrease had occurred for the natural vegetation types,in contrast to patch mergence and expansion of human land use types,and landscape fragmentation was intensified above 2500 m a.s.l.but declined below the elevation.The results indicated the dynamics of landscape composition and patch type level distribution in spite of the stability of the overall landscape pattern,and implied the potential role of roads,especially the low level roads on landscape changes.展开更多
A series of marine natural gas fields were recently discovered in oolitic dolomites of the Lower Triassic Feixianguan formation, northeastern Sichuan Basin, southwest China. The mechanism forming these reservoir dolom...A series of marine natural gas fields were recently discovered in oolitic dolomites of the Lower Triassic Feixianguan formation, northeastern Sichuan Basin, southwest China. The mechanism forming these reservoir dolomites is debatable, limiting the ability to characterize these reservoir successfully. Based on the investigation of the representative Dukouhe, Luojiazhai, and Puguang areas, this issue was addressed by examining the distribution, petrology, and geochemistry of the dolomites, the most comprehensive study to date was provided. Dolomitization occurred at a very early stage of diagenesis, as shown by the petrological features of the rock fabric. Vadose silt, which is composed primarily of dolomitic clasts, is found in the primary and secondary pores of the oolitic dolomite. This indicates that the overlying strata were subjected to dolomitization when the Feixianguan formation was located in the vadose zone. Therefore, it may be inferred that the dolomitization which occurred before the formation was exposed to meteoric conditions. The spatial distribution and geochemical characteristics of the dolomite indicate that dolomitization occurred as a result of seepage reflux. The degree of dolomitization decreases with increasing distance from the evaporative lagoon. Furthermore, the type and porosity of the dolomite vary in different zones of the upward-shoaling sequence, with the porosity gradually decreasing from the highest layer to the lowest layer. This reflects a close relationship between dolomitization and seawater evaporation during the formation of the dolomite. Geochemical analysis provided further evidence for the relationship between the dolomitization fluid and the coeval seawater. The 87Sr/86Sr and 813C isotopes, as well as the abundances of trace elements, Fe and Mn, indicate that seawater concentrated by evaporation acted as the dolomitization fluid. These results also show that dolomitization most likely occurred in a semi-closed diagenetic environment. Therefore, the main mechanism of oolitic dolomite formation is seepage reflux, which occurred at an early stage of diagenesis.展开更多
Both of Typhoon Winnie (9711) and Matsa (0509) underwent an extratropical transition (ET) process when they moved northward after landfall and affected Liaodong Peninsula. However, Matsa produced half as much rainfall...Both of Typhoon Winnie (9711) and Matsa (0509) underwent an extratropical transition (ET) process when they moved northward after landfall and affected Liaodong Peninsula. However, Matsa produced half as much rainfall as Winnie, although it struck Liaodong Peninsula directly while Winnie passed through the Bohai Sea. The relations between the ET processes and the precipitation over Liaodong Peninsula are examined. The result shows that the precipitation difference between Winnie and Matsa was closely related to the interactions between the westerly systems and typhoons during their ET processes. Winnie was captured by the upper westerly trough and then coupled with it when moving to the mid-latitudes, and the positive anomaly of moist potential vorticity (MPV) was transported downward from the upper troposphere over the remnant circulation of the tropical cyclone (TC). It was favorable to the interaction between tropical warm and wet air and westerly cold air, causing convective cloud clusters to form and develop. The rain belt composed of several meso-β cloud clusters over the Liaodong Peninsula, resulting in heavy rainfall. On the other hand, Matsa did not couple with any upper trough during its ET process and the positive anomaly of MPV in the upper troposphere and its downward transfer were weak. Only one meso-β cloud cluster occurred in Matsa’s rain belt during its ET process that tended to lessen rainfall over Liaodong Peninsula.展开更多
A case of hailstorm process occurring on 24 June 2006 in northwestern China was studied using satellite retrieval methodology. The particle effective radius (re) in the cloud tops was calculated by the reflectance in ...A case of hailstorm process occurring on 24 June 2006 in northwestern China was studied using satellite retrieval methodology. The particle effective radius (re) in the cloud tops was calculated by the reflectance in the 3.7 μm channel, and cloud-top microphysical properties were vividly represented using the RGB visual multispectral classification scheme. The microphysical zones of clouds and the processes of hail formation and develop-ment are inferred using the relations of cloud-top temperature (T) versus re for the tops of convective clouds. The results show that particle effective radius was smaller near the cloud base of hailstorm. There was a deep zone of diffusional droplet growth at the low level where the particles grew slowly with height, and there existed an evident area of small ice particles in the cloud top, suggesting the existence of a strong updraft in the clouds. The low glaciated temperature indicated a great depth from the cloud base to the glaciation height, which provided a deep layer of supercooled water for hail growth.展开更多
There have been few in-depth quantitative studies on soil erosion control and the ecological effects of land use changes. Soil erosion is the first eco-environmental problem particularly in mountainous areas. A major ...There have been few in-depth quantitative studies on soil erosion control and the ecological effects of land use changes. Soil erosion is the first eco-environmental problem particularly in mountainous areas. A major problem in the conversion of farmland to forest is to control soil erosion and improve ecological environment and thus to improve land use sustainability. We report results of calculation and analysis on soil erosion from converted farmland parcels in city of Mangshi (near the SW frontier of China) and the surrounding areas before and after the nine-year (2000-2009) project of converting farmland to forest. There was increased water conservation effect, as a result of decreased soil erosion. The average erosion modulus of the farmland returning to eco-friendly uses decreased by 5,535.59 t/km2·a and the control degree of soil erosion modulus reached 71.00%. The increased soil erosion after the returning in the typical sample area "did not drop, but increased" as the terraced fields decreased but sloping farmland inereased and yet woodland decreased.展开更多
Source spectra for moderate and small earthquakes are obtained after removing the path effect, site effect, and instrument response, etc. in the observed S-wave spectra. Based on the Brune source model and by means of...Source spectra for moderate and small earthquakes are obtained after removing the path effect, site effect, and instrument response, etc. in the observed S-wave spectra. Based on the Brune source model and by means of genetic algorithm, the source parameters including seismic moment, stress drop, source dimension, etc. are determined, the radiated seismic energy for small-to-moderate earthquakes is measured with consideration of underestimation and compensation brought forth by limited bandwidth of the instrument, and the scaling relationships of static and dynamic parameters for earthquakes展开更多
A coupled meteorology and aerosol/chemistry model WRF-Chem (Weather Research and Forecast model coupled with Chemistry) was used to conduct a pair of simulations with present-day (PD) and preindustrial (P1) emis...A coupled meteorology and aerosol/chemistry model WRF-Chem (Weather Research and Forecast model coupled with Chemistry) was used to conduct a pair of simulations with present-day (PD) and preindustrial (P1) emissions over East Asia to examine the aerosol indirect effect on clouds. As a result of an increase in aerosols in January, the cloud droplet number increased by 650 cm-3 over the ocean and East China, 400 cm-3 over Central and Southwest China, and less than 200 cm-3 over North China. The cloud liquid water path (LWP) increased by 40-60 g m-2 over the ocean and Southeast China and 30 g m-2 over Central China; the LWP in- creased less than 5 g m-2 or decreased by 5 g m2 over North China. The effective radius (Re) decreased by more than 4 pm over Southwest, Central, and Southeast China and 2 pm over North China. In July, variations in cloud properties were more uniform; the cloud droplet number increased by approximately 250400 cm-3, the LWP increased by approximately 30-50 g m 2, and Re decreased by approximately 3 μm over most regions of China. In response to cloud property changes from PI to PD, shortwave (SW) cloud radiative m-2 over the ocean and 10 forcing strengthened by 30 W W m-2 over Southeast China, and it weakened slightly by approximately 2-10 W m-2 over Central and Southwest China in January. In July, SW cloud radiative forcing strengthened by 15 W m-2 over Southeast and North China and weakened by l0 W m-2 over Central China. The different responses of SW cloud radiative forcing in different regions was related to cloud feedbacks and natural variability.展开更多
A total of 1939 receiver functions were obtained from 732 teleseismic events (M〉5.0) recorded at 21 broadband portable seis- mic stations on the Tengchong, Baoshan and Simao blocks and Yangtze platform. These stati...A total of 1939 receiver functions were obtained from 732 teleseismic events (M〉5.0) recorded at 21 broadband portable seis- mic stations on the Tengchong, Baoshan and Simao blocks and Yangtze platform. These stations were installed by the Institute of Crustal Dynamics, China Earthquake Administration during 2010 and 2011. Using the H-x stacking and searching method, crustal thickness and velocity ratio beneath the stations are obtained. Results show that crustal thickness and Poisson's ratio in- ferred from the velocity ratio clearly vary, and they illustrate block features in deep structures. Except for the Tengchong block crustal thickness increases from south to north along the same block and from west to east across different blocks. In the Yangtze platform, Poisson's ratio and crustal thickness show a consistent and significant increasing trend from south to north, possibly indicating that crustal thickening is caused mainly by lower crustal variations. In contrast, Poisson's ratio has no sig- nificant change within the Baoshan and Simao blocks. Such differences demonstrate that the Jinshajiang-Red River fault is a southern boundary of the South China block. The H-κ results inferred from three portable stations on the Tengchong block show high Poisson's ratios, but they vary clearly with back-azimuth, implying the existence of strong anisotropy in the crustal medium beneath the stations.展开更多
基金Under the auspices of National Natural Science Foundation of China(No.41371190,31021001)Scientific and Tech-nical Projects of Western China Transportation Construction,Ministry of Transport of China(No.2008-318-799-17)
文摘The structure and function of network is a central issue in landscape ecology.Road networks with hierarchical structure are crucial for understanding landscape dynamics.In this study,we compared the distribution of national road,provincial road,county road and rural road in the Three Parallel Rivers Region(TPRR)in Yunnan Province of China,and estimated the effect of roads(and other factors)on the spatial patterns of land use and land cover with logistic regression.In addition,we analyzed the land use and land cover change(LUCC)and landscape fragmentation in 1989–2005 along a buffer zone of the primary traffic corridor,national road G214.The results showed that,county and rural roads had much higher percentage of length extending into more natural habitats at higher elevation and steeper slope,compared with the higher level roads in this region.While the distributions of natural land cover types were dominated by environmental factors,human land use types i.e.,building land and farmland types were significantly related with roads,linking more closely with lower level roads.The LUCC dynamics(1989–2005)of the G214 buffer zone showed a general trend of land transformation from conifer forests and valley arid shrubs to building land and farmland,and from ice and snow to alpine shrubs and forests.With the length of G214 unchanged during the time,the overall landscape pattern changed little in the buffer zone,but habitat fragmentation and area decrease had occurred for the natural vegetation types,in contrast to patch mergence and expansion of human land use types,and landscape fragmentation was intensified above 2500 m a.s.l.but declined below the elevation.The results indicated the dynamics of landscape composition and patch type level distribution in spite of the stability of the overall landscape pattern,and implied the potential role of roads,especially the low level roads on landscape changes.
基金Project(2012CB214803)supported by the Major State Basic Research Development Program,ChinaProject(2011ZX5017-001-HZO2)supported by the National Science & Technology Special Project,China+1 种基金Project(2011D-5006-0105)supported by the PetroChina Research Fund,ChinaProject(SZD0414)supported by the Key Subject Construction Project of Sichuan Province,China
文摘A series of marine natural gas fields were recently discovered in oolitic dolomites of the Lower Triassic Feixianguan formation, northeastern Sichuan Basin, southwest China. The mechanism forming these reservoir dolomites is debatable, limiting the ability to characterize these reservoir successfully. Based on the investigation of the representative Dukouhe, Luojiazhai, and Puguang areas, this issue was addressed by examining the distribution, petrology, and geochemistry of the dolomites, the most comprehensive study to date was provided. Dolomitization occurred at a very early stage of diagenesis, as shown by the petrological features of the rock fabric. Vadose silt, which is composed primarily of dolomitic clasts, is found in the primary and secondary pores of the oolitic dolomite. This indicates that the overlying strata were subjected to dolomitization when the Feixianguan formation was located in the vadose zone. Therefore, it may be inferred that the dolomitization which occurred before the formation was exposed to meteoric conditions. The spatial distribution and geochemical characteristics of the dolomite indicate that dolomitization occurred as a result of seepage reflux. The degree of dolomitization decreases with increasing distance from the evaporative lagoon. Furthermore, the type and porosity of the dolomite vary in different zones of the upward-shoaling sequence, with the porosity gradually decreasing from the highest layer to the lowest layer. This reflects a close relationship between dolomitization and seawater evaporation during the formation of the dolomite. Geochemical analysis provided further evidence for the relationship between the dolomitization fluid and the coeval seawater. The 87Sr/86Sr and 813C isotopes, as well as the abundances of trace elements, Fe and Mn, indicate that seawater concentrated by evaporation acted as the dolomitization fluid. These results also show that dolomitization most likely occurred in a semi-closed diagenetic environment. Therefore, the main mechanism of oolitic dolomite formation is seepage reflux, which occurred at an early stage of diagenesis.
基金National Key Fundamental Project for Research Development and Plan (2004CB418301)Natural Science Foundation of China (40575018, 40675033)
文摘Both of Typhoon Winnie (9711) and Matsa (0509) underwent an extratropical transition (ET) process when they moved northward after landfall and affected Liaodong Peninsula. However, Matsa produced half as much rainfall as Winnie, although it struck Liaodong Peninsula directly while Winnie passed through the Bohai Sea. The relations between the ET processes and the precipitation over Liaodong Peninsula are examined. The result shows that the precipitation difference between Winnie and Matsa was closely related to the interactions between the westerly systems and typhoons during their ET processes. Winnie was captured by the upper westerly trough and then coupled with it when moving to the mid-latitudes, and the positive anomaly of moist potential vorticity (MPV) was transported downward from the upper troposphere over the remnant circulation of the tropical cyclone (TC). It was favorable to the interaction between tropical warm and wet air and westerly cold air, causing convective cloud clusters to form and develop. The rain belt composed of several meso-β cloud clusters over the Liaodong Peninsula, resulting in heavy rainfall. On the other hand, Matsa did not couple with any upper trough during its ET process and the positive anomaly of MPV in the upper troposphere and its downward transfer were weak. Only one meso-β cloud cluster occurred in Matsa’s rain belt during its ET process that tended to lessen rainfall over Liaodong Peninsula.
基金supported jointly by Chinese Ministry of Science and Technology (Grant 2005DIB3J099)Science Foundation of Shaanxi Province (Grant 2007D11)
文摘A case of hailstorm process occurring on 24 June 2006 in northwestern China was studied using satellite retrieval methodology. The particle effective radius (re) in the cloud tops was calculated by the reflectance in the 3.7 μm channel, and cloud-top microphysical properties were vividly represented using the RGB visual multispectral classification scheme. The microphysical zones of clouds and the processes of hail formation and develop-ment are inferred using the relations of cloud-top temperature (T) versus re for the tops of convective clouds. The results show that particle effective radius was smaller near the cloud base of hailstorm. There was a deep zone of diffusional droplet growth at the low level where the particles grew slowly with height, and there existed an evident area of small ice particles in the cloud top, suggesting the existence of a strong updraft in the clouds. The low glaciated temperature indicated a great depth from the cloud base to the glaciation height, which provided a deep layer of supercooled water for hail growth.
基金funded by the National Natural Science Foundation of China (No.40861014)
文摘There have been few in-depth quantitative studies on soil erosion control and the ecological effects of land use changes. Soil erosion is the first eco-environmental problem particularly in mountainous areas. A major problem in the conversion of farmland to forest is to control soil erosion and improve ecological environment and thus to improve land use sustainability. We report results of calculation and analysis on soil erosion from converted farmland parcels in city of Mangshi (near the SW frontier of China) and the surrounding areas before and after the nine-year (2000-2009) project of converting farmland to forest. There was increased water conservation effect, as a result of decreased soil erosion. The average erosion modulus of the farmland returning to eco-friendly uses decreased by 5,535.59 t/km2·a and the control degree of soil erosion modulus reached 71.00%. The increased soil erosion after the returning in the typical sample area "did not drop, but increased" as the terraced fields decreased but sloping farmland inereased and yet woodland decreased.
基金funded jointly by the Key Applied and Fundamental Research Project of Yunnan Province (2010CC006)the Key Project of Yunnan Province (JCYB-20080601-4)the Joint Earthquake Science Foundation of China (C08065)
文摘Source spectra for moderate and small earthquakes are obtained after removing the path effect, site effect, and instrument response, etc. in the observed S-wave spectra. Based on the Brune source model and by means of genetic algorithm, the source parameters including seismic moment, stress drop, source dimension, etc. are determined, the radiated seismic energy for small-to-moderate earthquakes is measured with consideration of underestimation and compensation brought forth by limited bandwidth of the instrument, and the scaling relationships of static and dynamic parameters for earthquakes
基金supported by the Knowledge Innovation Program of the Chinese Academy of Sciences (KZCX2-YW-Q11-04)the "Strategic Priority Research Program" of the Chinese Academy of Sciences (XDA05100502)
文摘A coupled meteorology and aerosol/chemistry model WRF-Chem (Weather Research and Forecast model coupled with Chemistry) was used to conduct a pair of simulations with present-day (PD) and preindustrial (P1) emissions over East Asia to examine the aerosol indirect effect on clouds. As a result of an increase in aerosols in January, the cloud droplet number increased by 650 cm-3 over the ocean and East China, 400 cm-3 over Central and Southwest China, and less than 200 cm-3 over North China. The cloud liquid water path (LWP) increased by 40-60 g m-2 over the ocean and Southeast China and 30 g m-2 over Central China; the LWP in- creased less than 5 g m-2 or decreased by 5 g m2 over North China. The effective radius (Re) decreased by more than 4 pm over Southwest, Central, and Southeast China and 2 pm over North China. In July, variations in cloud properties were more uniform; the cloud droplet number increased by approximately 250400 cm-3, the LWP increased by approximately 30-50 g m 2, and Re decreased by approximately 3 μm over most regions of China. In response to cloud property changes from PI to PD, shortwave (SW) cloud radiative m-2 over the ocean and 10 forcing strengthened by 30 W W m-2 over Southeast China, and it weakened slightly by approximately 2-10 W m-2 over Central and Southwest China in January. In July, SW cloud radiative forcing strengthened by 15 W m-2 over Southeast and North China and weakened by l0 W m-2 over Central China. The different responses of SW cloud radiative forcing in different regions was related to cloud feedbacks and natural variability.
基金supported by the National Natural Science Foundation of China(Grant No. 40974021)Basic Science and Research Special Project(Grant No. ZDJ2012-19)
文摘A total of 1939 receiver functions were obtained from 732 teleseismic events (M〉5.0) recorded at 21 broadband portable seis- mic stations on the Tengchong, Baoshan and Simao blocks and Yangtze platform. These stations were installed by the Institute of Crustal Dynamics, China Earthquake Administration during 2010 and 2011. Using the H-x stacking and searching method, crustal thickness and velocity ratio beneath the stations are obtained. Results show that crustal thickness and Poisson's ratio in- ferred from the velocity ratio clearly vary, and they illustrate block features in deep structures. Except for the Tengchong block crustal thickness increases from south to north along the same block and from west to east across different blocks. In the Yangtze platform, Poisson's ratio and crustal thickness show a consistent and significant increasing trend from south to north, possibly indicating that crustal thickening is caused mainly by lower crustal variations. In contrast, Poisson's ratio has no sig- nificant change within the Baoshan and Simao blocks. Such differences demonstrate that the Jinshajiang-Red River fault is a southern boundary of the South China block. The H-κ results inferred from three portable stations on the Tengchong block show high Poisson's ratios, but they vary clearly with back-azimuth, implying the existence of strong anisotropy in the crustal medium beneath the stations.