image: The different major types of disturbances of the Sun-Earth system affecting the Earth’s environment can be detected via their imprints on the ionosphere and middle/upper atmosphere: space weather, terrestrial and solar magnetic field long-term variations, greenhouse gases emissions, global atmospheric electric circuit transients, seismic activity, atmospheric waves. view more
Credit: ©Science China Press
Earth’s ecosystems and human activities are threatened by a broad spectrum of hazards threatening 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. These hazards leave distinguishable characteristic imprints on a critical layer of geospace: the Earth’s ionosphere, middle and upper atmosphere (IMUA).
Within this layer, the neutral and plasma components of our atmosphere and the geomagnetic field are strongly coupled via complex electrodynamic interactions which permanently couple the IMUA to the regions of space located above and below it: from above, solar activity and interplanetary space disturbances produce space weather events which perturb the Earth’s magnetosphere and the IMUA; disturbances propagating from below, mediated by atmospheric waves, electrodynamic coupling and electromagnetic radiation, are generated by earthquakes, the variability of solar irradiance, weather systems, and emissions of greenhouse gases; finally, secular changes of the geomagnetic field and transient variations in the global atmospheric electric circuit also influence the IMUA.
In an article published in SCIENCE CHINA Earth Sciences, an international team of scientists, building on the conclusions of an International Space Science Institute – Beijing (ISSI-Beijing) Forum organized in Beijing in September 2019, proposes the deployment of a global network of instruments observing the IMUA with a diversity of techniques to monitor, mitigate and possibly predict these hazards. They show that the optimal geometry for the deployment of this global observation system is a set of two great circles in quadrature: deployment of instruments in priority along the 120°E-60°W great meridian circle will cover in an optimal way the dominant geographic and geomagnetic latitude variations and earthquake activity along the circum-pacific fire belt. Complementary deployment along the 30°E-150°W meridians will capture both the longitude variations induced by land-ocean contrasts and the regions of maximum thunderstorm activity in Central Africa.
Using the Chinese Meridian Circle (CMP) network as a template, they give a preliminary description of the combination of instruments to be integrated and deployed along the 120°E-60°W great circle running across China, Australia and the Americas. Deployment of this network is the objective of Phase I of the International Meridian Circle Project (IMCP), an ambitious international project led by the Chinese Academy of Sciences. In this project, a large volume of data produced by different and complementary types of instruments (radio, optical and geophysical) will be assimilated to produce a global dynamic image of the key parameters of the IMUA. Advanced Artificial Intelligence tools will be used to detect the characteristic signatures of geospace disturbances in this image.
For more details, please refer to the upcoming paper "Scientific challenges and instrumentation for the International Meridian Circle Program", published in SCIENCE CHINA Earth Sciences, 2021, 64(12): 2090−2097, https://doi.org/10.1007/s11430-021-9841-8
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Science China Earth Sciences