Earth’s ecosystems and human activities are threatened by a broad spectrum of hazards of major importance for the safety of ground infrastructures,space systems and space flight:solar activity,earthquakes,atmospheric...Earth’s ecosystems and human activities are threatened by a broad spectrum of hazards of major importance for the safety of ground infrastructures,space systems and space flight:solar activity,earthquakes,atmospheric and climatic disturbances,changes in the geomagnetic field,fluctuations of the global electric circuit.Monitoring and understanding these major hazards to better predict and mitigate their effects is one of the greatest scientific and operational challenges of the 21st century.Though diverse,these hazards share one feature in common:they all leave their characteristic imprints on a critical layer of the Earth’s environment:its ionosphere,middle and upper atmosphere(IMUA).The objective of the International Meridian Circle Program(IMCP),a major international program led by the Chines Academy of Sciences(CAS),is to deploy,integrate and operate a global network of research and monitoring instruments to use the IMUA as a screen on which to detect these imprints.In this article,we first show that the geometry required for the IMCP global observation system leads to a deployment of instruments in priority along the 120°E-60°W great meridian circle,which will cover in an optimal way both the dominant geographic and geomagnetic latitude variations,possibly complemented by a second Great Circle along the 30°E-150°W meridians to capture longitude variations.Then,starting from the Chinese Meridian Project(CMP)network and using it as a template,we give a preliminary and promising description of the instruments to be integrated and deployed along the 120°E-60°W great circle running across China,Australia and the Americas.展开更多
Supersonic flows with high Mach number are ubiquitous in astrophysics. High-powered lasers also have the ability to drive high Mach number, radiating shock waves in laboratory plasmas, and recent experiments along the...Supersonic flows with high Mach number are ubiquitous in astrophysics. High-powered lasers also have the ability to drive high Mach number, radiating shock waves in laboratory plasmas, and recent experiments along these lines have made it possible to recreate analogs of high Mach-number astrophysical flows under controlled conditions. Streak cameras such as the Rochester optical streak system(ROSS) are particularly helpful in diagnosing such experiments,because they acquire spatially resolved measurements of the radiating gas continuously over a large time interval,making it easy to observe how any shock waves and ablation fronts present in the system evolve with time. This paper summarizes new ROSS observations of a laboratory analog of the collision of a stellar wind with an ablating planetary atmosphere embedded within a magnetosphere. We find good agreement between the observed ROSS data and numerical models obtained with the FLASH code, but only when the effects of optical depth are properly taken into account.展开更多
基金This work was supported by the International PartnershipProgram of Chinese Academy of Sciences(Grant No.183311KYSB20200003)the Beijing Municipal Science and Technology Commission(Grant No.Z181100002918001).
文摘Earth’s ecosystems and human activities are threatened by a broad spectrum of hazards of major importance for the safety of ground infrastructures,space systems and space flight:solar activity,earthquakes,atmospheric and climatic disturbances,changes in the geomagnetic field,fluctuations of the global electric circuit.Monitoring and understanding these major hazards to better predict and mitigate their effects is one of the greatest scientific and operational challenges of the 21st century.Though diverse,these hazards share one feature in common:they all leave their characteristic imprints on a critical layer of the Earth’s environment:its ionosphere,middle and upper atmosphere(IMUA).The objective of the International Meridian Circle Program(IMCP),a major international program led by the Chines Academy of Sciences(CAS),is to deploy,integrate and operate a global network of research and monitoring instruments to use the IMUA as a screen on which to detect these imprints.In this article,we first show that the geometry required for the IMCP global observation system leads to a deployment of instruments in priority along the 120°E-60°W great meridian circle,which will cover in an optimal way both the dominant geographic and geomagnetic latitude variations,possibly complemented by a second Great Circle along the 30°E-150°W meridians to capture longitude variations.Then,starting from the Chinese Meridian Project(CMP)network and using it as a template,we give a preliminary and promising description of the instruments to be integrated and deployed along the 120°E-60°W great circle running across China,Australia and the Americas.
基金the DOE NLUF program DE-FOA-0001568the Data Analysis and Visualization Cyber Infrastructure program OCI-0959097
文摘Supersonic flows with high Mach number are ubiquitous in astrophysics. High-powered lasers also have the ability to drive high Mach number, radiating shock waves in laboratory plasmas, and recent experiments along these lines have made it possible to recreate analogs of high Mach-number astrophysical flows under controlled conditions. Streak cameras such as the Rochester optical streak system(ROSS) are particularly helpful in diagnosing such experiments,because they acquire spatially resolved measurements of the radiating gas continuously over a large time interval,making it easy to observe how any shock waves and ablation fronts present in the system evolve with time. This paper summarizes new ROSS observations of a laboratory analog of the collision of a stellar wind with an ablating planetary atmosphere embedded within a magnetosphere. We find good agreement between the observed ROSS data and numerical models obtained with the FLASH code, but only when the effects of optical depth are properly taken into account.
