Deployments of seismic stations in Antarctica are an ambitious project to improve the spatial resolution of the Antarctic Plate and surrounding regions. Several international programs had been conducted in wide area o...Deployments of seismic stations in Antarctica are an ambitious project to improve the spatial resolution of the Antarctic Plate and surrounding regions. Several international programs had been conducted in wide area of the Antarctic continent during the International Polar Year (IPY 2007-2008). The “Antarctica’s GAmburtsev Province (AGAP)”, the “GAmburtsev Mountain SEISmic experiment (GAMSEIS)” as a part of AGAP, and the “Polar Earth Observing Network (POLENET)” were major contributions to the IPY. The AGAP/GAMSEIS was an internationally coordinated deployments of more than few tens of broadband seismographs over the wide area of East Antarctica. Detailed information on crustal thickness and mantle structure provides key constraints on an origin of the Gamburtsev Mountains;and more broad structure and evolution of the East Antarctic craton and sub-glacial environment. From POLENET data obtained, local and regional signals associated with ice movements were recorded together with a significant number of teleseismic events. Moreover, seismic deployments have been carried out in the Lützow-Holm Bay (LHB), East Antarctica, by Japanese activities. The recorded teleseismic and local events are of sufficient quality to image the structure and dynamics of the crust and mantle, such as the studies by receiver functions suggesting a heterogeneous upper mantle. In addition to studies on the shallow part of the Earth, we place emphasis on these seismic deployments’ ability to image the Earth’s deep interior, as viewed from Antarctica, as a large aperture array in the southern high latitude.展开更多
Gravitation is one of the central forces playing an important role in formation of natural systems like galaxies and planets. Gravitational forces between particles of a gaseous cloud transform the cloud into spherica...Gravitation is one of the central forces playing an important role in formation of natural systems like galaxies and planets. Gravitational forces between particles of a gaseous cloud transform the cloud into spherical shells and disks of higher density during gravitational contraction. The density can reach that of a solid body. The theoretical model was tested to model the formation of a spiral galaxy and Saturn. The formations of a spiral galaxy and Saturn and its disk are simulated using a novel N-body self-gravitational model. It is demonstrated that the formation of the spirals of the galaxy and disk of the planet is the result of gravitational contraction of a slowly rotated particle cloud that has a shape of slightly deformed sphere for Saturn and ellipsoid for the spiral galaxy. For Saturn, the sphere was flattened by a coefficient of 0.8 along the axis of rotation. During the gravitational contraction, the major part of the cloud transformed into a planet and a minor part transformed into a disk. The thin structured disk is a result of the electromagnetic interaction in which the magnetic forces acting on charged particles of the cloud originate from the core of the planet.展开更多
Jupiter’s magnetic field is thought to be generated in its deep metallic hydrogen region through dynamo action,yet the detailed dynamic process remains poorly understood.Numerical simulations have produced Jupiter-li...Jupiter’s magnetic field is thought to be generated in its deep metallic hydrogen region through dynamo action,yet the detailed dynamic process remains poorly understood.Numerical simulations have produced Jupiter-like magnetic fields,albeit using different control parameters and reference state models.In this study,we investigate the influence of different reference state models,based on ab initio calculations and based on the polytropic equation of state.In doing so,we perform five anelastic convection dynamo simulations that can be divided into two groups.In each group,different reference states are used while other control parameters and conditions are set to be identical.We find the reference state model can be very influential for the simulations in which buoyancy force is dominant over the Lorentz force.In this regime,different dynamical outcomes can be attributed to the effective buoyancy force resulting from different reference states.For simulations in which the Lorentz force is dominant over the buoyancy force,however,dynamo actions tend to be insensitive to different reference state models.If Jupiter’s dynamo is in a strong field regime,i.e.,the Lorentz force plays a dominant role,our numerical results suggest that Jupiter’s internal reference state,which remains poorly constrained,may play a minor role in the dynamo process of the planet.展开更多
文摘Deployments of seismic stations in Antarctica are an ambitious project to improve the spatial resolution of the Antarctic Plate and surrounding regions. Several international programs had been conducted in wide area of the Antarctic continent during the International Polar Year (IPY 2007-2008). The “Antarctica’s GAmburtsev Province (AGAP)”, the “GAmburtsev Mountain SEISmic experiment (GAMSEIS)” as a part of AGAP, and the “Polar Earth Observing Network (POLENET)” were major contributions to the IPY. The AGAP/GAMSEIS was an internationally coordinated deployments of more than few tens of broadband seismographs over the wide area of East Antarctica. Detailed information on crustal thickness and mantle structure provides key constraints on an origin of the Gamburtsev Mountains;and more broad structure and evolution of the East Antarctic craton and sub-glacial environment. From POLENET data obtained, local and regional signals associated with ice movements were recorded together with a significant number of teleseismic events. Moreover, seismic deployments have been carried out in the Lützow-Holm Bay (LHB), East Antarctica, by Japanese activities. The recorded teleseismic and local events are of sufficient quality to image the structure and dynamics of the crust and mantle, such as the studies by receiver functions suggesting a heterogeneous upper mantle. In addition to studies on the shallow part of the Earth, we place emphasis on these seismic deployments’ ability to image the Earth’s deep interior, as viewed from Antarctica, as a large aperture array in the southern high latitude.
文摘Gravitation is one of the central forces playing an important role in formation of natural systems like galaxies and planets. Gravitational forces between particles of a gaseous cloud transform the cloud into spherical shells and disks of higher density during gravitational contraction. The density can reach that of a solid body. The theoretical model was tested to model the formation of a spiral galaxy and Saturn. The formations of a spiral galaxy and Saturn and its disk are simulated using a novel N-body self-gravitational model. It is demonstrated that the formation of the spirals of the galaxy and disk of the planet is the result of gravitational contraction of a slowly rotated particle cloud that has a shape of slightly deformed sphere for Saturn and ellipsoid for the spiral galaxy. For Saturn, the sphere was flattened by a coefficient of 0.8 along the axis of rotation. During the gravitational contraction, the major part of the cloud transformed into a planet and a minor part transformed into a disk. The thin structured disk is a result of the electromagnetic interaction in which the magnetic forces acting on charged particles of the cloud originate from the core of the planet.
基金supported by the B-type Strategic Priority Program of the CAS (XDB41000000)the preresearch project on Civil Aerospace Technologies of CNSA (D020308)the Macao Foundationsupport from STFC, grant number ST/S00047X/1 held at the University of Leeds.
文摘Jupiter’s magnetic field is thought to be generated in its deep metallic hydrogen region through dynamo action,yet the detailed dynamic process remains poorly understood.Numerical simulations have produced Jupiter-like magnetic fields,albeit using different control parameters and reference state models.In this study,we investigate the influence of different reference state models,based on ab initio calculations and based on the polytropic equation of state.In doing so,we perform five anelastic convection dynamo simulations that can be divided into two groups.In each group,different reference states are used while other control parameters and conditions are set to be identical.We find the reference state model can be very influential for the simulations in which buoyancy force is dominant over the Lorentz force.In this regime,different dynamical outcomes can be attributed to the effective buoyancy force resulting from different reference states.For simulations in which the Lorentz force is dominant over the buoyancy force,however,dynamo actions tend to be insensitive to different reference state models.If Jupiter’s dynamo is in a strong field regime,i.e.,the Lorentz force plays a dominant role,our numerical results suggest that Jupiter’s internal reference state,which remains poorly constrained,may play a minor role in the dynamo process of the planet.
