GEM: Global MHD Simulations of Dayside Magnetospheric Processes and Their Mapping to the Ionosphere

9301051里昂将进行太阳风与磁层和电离层相互作用的全球磁流体动力学模拟，以帮助解释和分析与GEM计划一起进行的低空和地面观测。 这些计算将使用地球观测系统观测活动实际期间的太阳风数据，以尽可能准确地反映这些时间的磁层状况。 模拟的结果将从磁层顶和尖点区域映射到近地空间和电离层，在那里可以与观测结果进行比较。 要映射的主要量将是磁场拓扑结构，场向电流和粒子分布。 经验和理论考虑表明，这些映射可以提供有用的信息，例如，在地面雷达观测中看到的尺度，即使计算网格相对更粗糙。 用于这种映射的磁场模型是从磁层的MHD解自洽地确定的。 该模型还将用于绘制电离层观测图，将其传回磁层顶区域，并将向全球监测系统参与者提供场模型。 这些比较将导致更好地了解全球MHD模型的优点和缺点，以及必须包括哪些额外的物理。 还将利用不同的太阳风输入数据进行研究，以涵盖各种可能的条件。 这些模拟将被用来提供一个参数表示法向场和切向速度在磁层顶。 这种表示是一个模块化磁层环流模型的重要输入。 用于观测活动的随时间变化的太阳风情况也将以这种方式进行分析，以发现静态模型可以规定多少实际的磁层顶切向电场。 ***

9301051 Lyon Global MHD simulations of the interaction of the solar wind with the magnetosphere and ionosphere will be performed as an aid to interpreting and analyzing low altitude and ground-based observations done in conjunction with the GEM program. The calculations will use solar wind data for the actual period of the GEM observing campaigns to produce as accurate a representation of mangetospheric conditions as possible for those times. The results from the simulations will be mapped from the mangetopause and cusp regions to near earth space and to the ionosphere where they may be compared with observations. The primary quanities to be mapped will be magnetic field topology, field-aligned currents and particle distributions. Experience and theoretical considerations show that these mappings can provide useful information on the scales seen in the ground-based radar observations, for example, even though the calculation grid is relatively more coarse. The magnetic field model used for this mapping is determined self- consistently from the MHD solution for the magnetosphere. This model will also be used to map the ionospheric observations back out to the region of the magnetopause, and the field models will be provided to GEM participants. These comparison will lead to a better appreciation for the strengths and weaknesses of the global MHD model and what additional physics must be included. Studies will also be conducted with varying solar wind input data to cover a wide range of possible conditions. These simulations will then be used to provide a parametric representation of the normal field and the tangential velocity at the magnetopause. This representation is an important input to a modular magnetospheric circulation model. The time varying solar wind cases used for the observational campaigns will also be analyzed in this fashion to find how much of the actual magnetopause tangential eletric field can be prescribed by a static model. ***