Aiming at the influence of ocean mesoscale eddy on underwater acoustic propagation, a theoretical computation model of ocean mesoscale eddy was established based on the in-situ hydrographic data in the sea area of oce...Aiming at the influence of ocean mesoscale eddy on underwater acoustic propagation, a theoretical computation model of ocean mesoscale eddy was established based on the in-situ hydrographic data in the sea area of ocean mesoscale eddy. An underwater acoustic modeI-MMPE was used to simulate the acoustic propagation under the influence of different types, different intensities and positions of eddies, and different frequencies and depths of sources. It is found that warm-core eddy can make the convergence zone ＂move back＂ and the width of it increases, while cold-core eddy can make the convergence zone ＂move forward＂ and the width of it decreases. The bigger the intensity of eddy, the more notable the ＂forward ＂or ＂back ＂effect. Sound source located depths and source frequencies can change the acoustic propagation characteristics in the eddy area.展开更多
Urban agglomerations are spatial entities that promote the development of ‘new urbanization' processes within China. In this context, the concept of ‘multiscale urban agglomeration spaces' encompasses three ...Urban agglomerations are spatial entities that promote the development of ‘new urbanization' processes within China. In this context, the concept of ‘multiscale urban agglomeration spaces' encompasses three linked levels: macroscale urban agglomerations, mesoscale cities, and microscale urban centers. Applying a series of multidisciplinary integrated research methods drawn from geography, urban planning, and architecture, this paper reveals two intensive utilization laws that can be generalized to apply to multiscale urban agglomeration spaces, top-to-bottom ‘positive transmission' linkage and inside-to-outside ‘negative transmission' movement. This paper also proposes optimization transmission theory and policy decision technical pathways that can be applied to these three urban agglomeration spatial scales. Specific technical pathways of transmission include intensive expansion and simulated decision-making in macroscale urban agglomerations, ecology, production, and living space intensive layout and dynamic decision-making in mesoscale cities, and four cores(i.e., ‘single, ring, axis, and pole core') progressive linkage and intensive optimization decision-making in microscale urban centers. The theory and technical pathways proposed in this paper solve the technical problem of optimization and provide intensive methods that can be applied not only at the individual level but also at multiple scales in urban agglomeration spaces. This study also advances a series of comprehensive technical solutions that can be applied to both compact and smart growth cities as well as to urban agglomerations. Solid theoretical support is provided for the optimization of Chinese land development, urbanization, agricultural development, and ecological security.展开更多
The propagation of oceanic mesoscale signals in the South China Sea(SCS) is mapped from satellite altimetric observations and an eddy-resolving global ocean model by using the maximum cross-correlation(MCC) method.Sig...The propagation of oceanic mesoscale signals in the South China Sea(SCS) is mapped from satellite altimetric observations and an eddy-resolving global ocean model by using the maximum cross-correlation(MCC) method.Significant mesoscale signals propagate along two major bands of high variability.The northern band is located west of the Luzon Strait,characterized by southwestward eddy propagation.Although eddies are the most active in winter,their southwestward migrations,steered by bathymetry,occur throughout the year.Advection by the mean flow plays a secondary role in modulating the propagating speed.The southern eddy band lies in the southwest part of the SCS deep basin and is oriented in an approximately meridional direction.Mesoscale variability propagates southward along the band in autumn.This southward eddy pathway could not be explained by mean flow advection and is likely related to eddy detachments from the western boundary current due to nonlinear effects.Our mapping of eddy propagation velocities provides important information for further understanding eddy dynamics in the SCS.展开更多
This study presents observation and detailed analysis on the double layers （DLs） in the ramp and the foreshock contacting with the foot of the terrestrial bow shock by THEMIS on September 14, 2008 under enhanced dyn...This study presents observation and detailed analysis on the double layers （DLs） in the ramp and the foreshock contacting with the foot of the terrestrial bow shock by THEMIS on September 14, 2008 under enhanced dynamic pressure in the solar wind. The results reveal that： （1） The time duration of the double layers is nus 10-40 mV/m. （2） On assuming a propagation speed at the ion mainly 3-8 ms, and their max parallel electric field is miacoustic speed （vs）, their spatial scale is estimated to be 0.3-1.15 km （about 75-200 2D）. （3） The net potential drop of DLs is estimated to be 5-32 V. （4） The DLs in the ramp and the foreshock contacting to the foot of the bow shock is current-carrying as a result of development and evolution of nonlinear phase of instability in the self-consistent current-carrying plasma. The DLs may play an important role in strong turbulence in the foreshock contacting with the foot of the bow shock.展开更多
基金the National Natural Science Foundation of China (Grants No. 41176085 and 41075045), for financially supporting this research
文摘Aiming at the influence of ocean mesoscale eddy on underwater acoustic propagation, a theoretical computation model of ocean mesoscale eddy was established based on the in-situ hydrographic data in the sea area of ocean mesoscale eddy. An underwater acoustic modeI-MMPE was used to simulate the acoustic propagation under the influence of different types, different intensities and positions of eddies, and different frequencies and depths of sources. It is found that warm-core eddy can make the convergence zone ＂move back＂ and the width of it increases, while cold-core eddy can make the convergence zone ＂move forward＂ and the width of it decreases. The bigger the intensity of eddy, the more notable the ＂forward ＂or ＂back ＂effect. Sound source located depths and source frequencies can change the acoustic propagation characteristics in the eddy area.
基金Under the auspices of Major Program of the National Natural Science Foundation of China ‘Coupled mechanisms and interactive coercing effects between urbanization and eco-environment in mega-urban agglomerations’(No.41590842)
文摘Urban agglomerations are spatial entities that promote the development of ‘new urbanization' processes within China. In this context, the concept of ‘multiscale urban agglomeration spaces' encompasses three linked levels: macroscale urban agglomerations, mesoscale cities, and microscale urban centers. Applying a series of multidisciplinary integrated research methods drawn from geography, urban planning, and architecture, this paper reveals two intensive utilization laws that can be generalized to apply to multiscale urban agglomeration spaces, top-to-bottom ‘positive transmission' linkage and inside-to-outside ‘negative transmission' movement. This paper also proposes optimization transmission theory and policy decision technical pathways that can be applied to these three urban agglomeration spatial scales. Specific technical pathways of transmission include intensive expansion and simulated decision-making in macroscale urban agglomerations, ecology, production, and living space intensive layout and dynamic decision-making in mesoscale cities, and four cores(i.e., ‘single, ring, axis, and pole core') progressive linkage and intensive optimization decision-making in microscale urban centers. The theory and technical pathways proposed in this paper solve the technical problem of optimization and provide intensive methods that can be applied not only at the individual level but also at multiple scales in urban agglomeration spaces. This study also advances a series of comprehensive technical solutions that can be applied to both compact and smart growth cities as well as to urban agglomerations. Solid theoretical support is provided for the optimization of Chinese land development, urbanization, agricultural development, and ecological security.
基金Supported by the Knowledge Innovation Program of the Chinese Academy of Sciences (KZCX1-YW-12-01)the National Natural Science Foundation of China (Nos.40806006,40876009)+1 种基金the Knowledge Innovation Program of the Chinese Academy of Sciences (No.KZCX2-YW-BR-04),the Qianren ProjectThe OFES simulation was conducted on the Earth Simulator under the support of JAMSTEC
文摘The propagation of oceanic mesoscale signals in the South China Sea(SCS) is mapped from satellite altimetric observations and an eddy-resolving global ocean model by using the maximum cross-correlation(MCC) method.Significant mesoscale signals propagate along two major bands of high variability.The northern band is located west of the Luzon Strait,characterized by southwestward eddy propagation.Although eddies are the most active in winter,their southwestward migrations,steered by bathymetry,occur throughout the year.Advection by the mean flow plays a secondary role in modulating the propagating speed.The southern eddy band lies in the southwest part of the SCS deep basin and is oriented in an approximately meridional direction.Mesoscale variability propagates southward along the band in autumn.This southward eddy pathway could not be explained by mean flow advection and is likely related to eddy detachments from the western boundary current due to nonlinear effects.Our mapping of eddy propagation velocities provides important information for further understanding eddy dynamics in the SCS.
基金supported by the National Natural Science Foundation of China(Grant No.41304132)the 53-Class General Financial Grant from the China Postdoctoral Science Foundation(Grant No.2013M532115)
文摘This study presents observation and detailed analysis on the double layers （DLs） in the ramp and the foreshock contacting with the foot of the terrestrial bow shock by THEMIS on September 14, 2008 under enhanced dynamic pressure in the solar wind. The results reveal that： （1） The time duration of the double layers is nus 10-40 mV/m. （2） On assuming a propagation speed at the ion mainly 3-8 ms, and their max parallel electric field is miacoustic speed （vs）, their spatial scale is estimated to be 0.3-1.15 km （about 75-200 2D）. （3） The net potential drop of DLs is estimated to be 5-32 V. （4） The DLs in the ramp and the foreshock contacting to the foot of the bow shock is current-carrying as a result of development and evolution of nonlinear phase of instability in the self-consistent current-carrying plasma. The DLs may play an important role in strong turbulence in the foreshock contacting with the foot of the bow shock.
