官方确认：“旅行者1号”已经离开太阳系--It’s official-Voyager has left the solar system. Science,2013, Vol.341, No.6151.<br> NASA证实，经过36年的疾速，“旅行者1号”已经进入星际空间，尽管它的传感器出了故障，...官方确认：“旅行者1号”已经离开太阳系--It’s official-Voyager has left the solar system. Science,2013, Vol.341, No.6151.<br> NASA证实，经过36年的疾速，“旅行者1号”已经进入星际空间，尽管它的传感器出了故障，它的能量所剩无几。最新数据显示，“旅行者1号”穿越了太阳风层最外层，这表明它已经离开太阳系，它与地球的距离已经是海王星轨道距地球距离的六倍。至于准确的离开日期，“旅行者”项目组的科学家一致认为是2012年8月25日，那一天，“旅行者1号”的一个仪器记录到产生自太阳风层内的宇宙射线的暴跌，另一个仪器记录到太阳风层之外、银河系产生的宇宙射线的同步增长。不过，并不是所有科学家都认同这个结论，美国西南研究院的空间物理学家David McComas 认为，除非磁场方向改变，否则不能说明“旅行者1号”已经离开太阳系。Michigan大学的几位研究人员也不认为“旅行者1号”已经离开。2020年开始，“旅行者1号”的仪器必须通过打开和关闭来分享电源，而到2025年，所有仪器都会被关闭。无论如何，可能仍然有足够的时间等待磁场方向的改变，或者不变。展开更多
We present a newly developed global magnetohydrodynamic(MHD) model to study the responses of the Earth's magnetosphere to the solar wind. The model is established by using the space-time conservation element and s...We present a newly developed global magnetohydrodynamic(MHD) model to study the responses of the Earth's magnetosphere to the solar wind. The model is established by using the space-time conservation element and solution element(CESE) method in general curvilinear coordinates on a six-component grid system. As a preliminary study, this paper is to present the model's numerical results of the quasi-steady state and the dynamics of the Earth's magnetosphere under steady solar wind flow with due northward interplanetary magnetic field(IMF). The model results are found to be in good agreement with those published by other numerical magnetospheric models.展开更多
With the approaching of the 24th solar cycle peak year （2012-2014）, the impacts of super solar storms on the geospace envi- ronment have drawn attentions. Based on the geomagnetic field observations during Carringto...With the approaching of the 24th solar cycle peak year （2012-2014）, the impacts of super solar storms on the geospace envi- ronment have drawn attentions. Based on the geomagnetic field observations during Carrington event in 1859, we estimate the interplanetary solar wind conditions at that time, and investigate the response of the magnetosphere-ionosphere system to this extreme solar wind conditions using global 3D MHD simulations. The main findings include： l） The day-side magnetopause and bow shock are compressed to 4.3 and 6.0 Re （Earth radius）, and their flanks are also strongly compressed. The magneto- pause shifts inside the geosynchronous orbit, exposing geosynchronous satellites in the solar wind in the magnetosheath. 2） During the storm, the region-1 current increases by about 60 times, and the cross polar potential drop increases by about 80 times; the reconnection voltage is about 5 to 6 times larger than the average storms, which means a larger amount of the solar wind energy enters the magnetosphere, resulting in strong space weather phenomena.展开更多
The magnetosphere is the outermost layer of the geospace, and the interaction of the solar wind with the magnetosphere is the key element of the space weather cause-and-effect chain process from the Sun to Earth, whic...The magnetosphere is the outermost layer of the geospace, and the interaction of the solar wind with the magnetosphere is the key element of the space weather cause-and-effect chain process from the Sun to Earth, which is one of the most challenging scientific problems in the geospace weather study. The nonlinearity, multiple component, and time-dependent nature of the geospace make it very difficult to describe the physical process in geospace using traditional analytic analysis approach. Numerical simulations, a new research tool developed in recent decades, have a deep impact on the theory and application of the geospace. MHD simulations started at the end of the 1970s, and the initial study was limited to two-dimensional (2D) cases. Due to the intrinsic three-dimensional (3D) characteristics of the geospace, 3D MHD simulations emerged in the 1980s, in an attempt to model the large-scale structures and fundamental physical processes in the magnetosphere. They started to combine with the space exploration missions in the 1990s and make comparisons with observations. Physics-based space weather forecast models started to be developed in the 21st century. Currently only a few space-power countries such as USA and Japan have developed 3D magnetospheric MHD models. With the rapid advance of space science in China, we have developed a new global MHD model, namely PPMLR-MHD, which has high order spatial accuracy and low numerical dissipation. In this review, we will briefly introduce the global 3D MHD modeling, especially the PPMLR-MHD code, and summarize our recent work based on the PPMLR-MHD model, with an emphasis on the interaction of interplanetary shocks with the magnetosphere, large-scale current systems, reconnection voltage and transpolar potential drop, and Kelvin-Helmholtz (K-H) instability at the magnetopause.展开更多
文摘官方确认：“旅行者1号”已经离开太阳系--It’s official-Voyager has left the solar system. Science,2013, Vol.341, No.6151.<br> NASA证实，经过36年的疾速，“旅行者1号”已经进入星际空间，尽管它的传感器出了故障，它的能量所剩无几。最新数据显示，“旅行者1号”穿越了太阳风层最外层，这表明它已经离开太阳系，它与地球的距离已经是海王星轨道距地球距离的六倍。至于准确的离开日期，“旅行者”项目组的科学家一致认为是2012年8月25日，那一天，“旅行者1号”的一个仪器记录到产生自太阳风层内的宇宙射线的暴跌，另一个仪器记录到太阳风层之外、银河系产生的宇宙射线的同步增长。不过，并不是所有科学家都认同这个结论，美国西南研究院的空间物理学家David McComas 认为，除非磁场方向改变，否则不能说明“旅行者1号”已经离开太阳系。Michigan大学的几位研究人员也不认为“旅行者1号”已经离开。2020年开始，“旅行者1号”的仪器必须通过打开和关闭来分享电源，而到2025年，所有仪器都会被关闭。无论如何，可能仍然有足够的时间等待磁场方向的改变，或者不变。
基金supported by the National Basic Research Program of China(Grant Nos.2012CB825601,2014CB845903,2012CB825604)the National Natural Science Foundation of China(Grant Nos.41031066,41231068,41274192,41074121,41204127,41174122)+1 种基金the Knowledge Innovation Program of the Chinese Academy of Sciences(Grant No.KZZD-EW-01-4)the Specialized Research Fund for State Key Laboratories
文摘We present a newly developed global magnetohydrodynamic(MHD) model to study the responses of the Earth's magnetosphere to the solar wind. The model is established by using the space-time conservation element and solution element(CESE) method in general curvilinear coordinates on a six-component grid system. As a preliminary study, this paper is to present the model's numerical results of the quasi-steady state and the dynamics of the Earth's magnetosphere under steady solar wind flow with due northward interplanetary magnetic field(IMF). The model results are found to be in good agreement with those published by other numerical magnetospheric models.
基金supported by National Natural Science Foundation of China (Grant Nos. 40921063, 40974106,40831060)the special fund for State Key Laboratory of Ministry of Science and Technology
文摘With the approaching of the 24th solar cycle peak year （2012-2014）, the impacts of super solar storms on the geospace envi- ronment have drawn attentions. Based on the geomagnetic field observations during Carrington event in 1859, we estimate the interplanetary solar wind conditions at that time, and investigate the response of the magnetosphere-ionosphere system to this extreme solar wind conditions using global 3D MHD simulations. The main findings include： l） The day-side magnetopause and bow shock are compressed to 4.3 and 6.0 Re （Earth radius）, and their flanks are also strongly compressed. The magneto- pause shifts inside the geosynchronous orbit, exposing geosynchronous satellites in the solar wind in the magnetosheath. 2） During the storm, the region-1 current increases by about 60 times, and the cross polar potential drop increases by about 80 times; the reconnection voltage is about 5 to 6 times larger than the average storms, which means a larger amount of the solar wind energy enters the magnetosphere, resulting in strong space weather phenomena.
基金supported by the National Basic Research Program of China (Grant No.2012CB825602)National Natural Science Foundation of China (Grant Nos.41204118 & 41231067)in part by the Specialized Research Fund for State Key Laboratories of China
文摘The magnetosphere is the outermost layer of the geospace, and the interaction of the solar wind with the magnetosphere is the key element of the space weather cause-and-effect chain process from the Sun to Earth, which is one of the most challenging scientific problems in the geospace weather study. The nonlinearity, multiple component, and time-dependent nature of the geospace make it very difficult to describe the physical process in geospace using traditional analytic analysis approach. Numerical simulations, a new research tool developed in recent decades, have a deep impact on the theory and application of the geospace. MHD simulations started at the end of the 1970s, and the initial study was limited to two-dimensional (2D) cases. Due to the intrinsic three-dimensional (3D) characteristics of the geospace, 3D MHD simulations emerged in the 1980s, in an attempt to model the large-scale structures and fundamental physical processes in the magnetosphere. They started to combine with the space exploration missions in the 1990s and make comparisons with observations. Physics-based space weather forecast models started to be developed in the 21st century. Currently only a few space-power countries such as USA and Japan have developed 3D magnetospheric MHD models. With the rapid advance of space science in China, we have developed a new global MHD model, namely PPMLR-MHD, which has high order spatial accuracy and low numerical dissipation. In this review, we will briefly introduce the global 3D MHD modeling, especially the PPMLR-MHD code, and summarize our recent work based on the PPMLR-MHD model, with an emphasis on the interaction of interplanetary shocks with the magnetosphere, large-scale current systems, reconnection voltage and transpolar potential drop, and Kelvin-Helmholtz (K-H) instability at the magnetopause.
