Research on the coupling process between the Magnetosphere-Ionosphere-Thermosphere by using HALL-MHD simulation predictions

为了更好地理解磁层-电离层-热层的耦合过程，建立一个考虑所有耦合过程的模拟程序是非常重要的。这个项目的目的是通过开发这样的仿真代码来更深入地理解耦合过程。我们以Kataoka [1999]的模拟程序为基础，尝试加入新的元素，如（1）热层中性风产生的发电电场，（2）电子密度低时出现的场向电场，（3）弯曲磁场的影响，（4）动力学Alfven波精细结构的影响，认为Hall项在无碰撞重联中是重要的，Hall MHD可能比电阻MHD更适合于模拟和理论。在GEOTAIL的磁层顶（MP）发现了一些实验证据。我们很想用CLUSTER的数据去查一下，看看是否真的有一个Hall ...更多信息 通过观察异相磁场来确定接近重接线的电流。CLUSTER由四颗相同的子卫星组成，它们一起飞行。它们中的每一个都有磁场和电场。粒子和等离子体波仪器。当将我们的数据与来自已发表的模拟的预期进行比较时，存在一些困难，例如：（1）MP上存在密度梯度，但迄今为止所有模拟都是在均匀背景下进行的。密度梯度一定会使事物不那么对称。例如，在哪一侧霍尔电流会更强，是磁鞘还是磁层？（2）当4颗卫星飞过特定的重连场景时，应该看到什么？为了了解MP周围发生的无碰撞重联过程的第一步，我们试图研究一个简单的重联方案与2-D霍尔-MHD代码，我们以前应用于磁层-电离层耦合过程与极光弧，但在本研究中，我们设置离子中性碰撞频率为零，并考虑压力梯度项，并相应地修改边界条件和背景参数。到目前为止，我们的模拟代码可以解决MP的情况下，而观察到的卫星，如GEOTAIL和集群。少

In order to understand the coupling process between the magnetosphere-ionosphere-thermosphere, it is of vital importance to develop a simulation code which considers all coupling processes. An aim of this project is to understand the coupling process more deeply by developing such a simulation code. We were based on the simulation code made by Kataoka [1999], and made an attempt to include new elements such as (1)dynamo electric field originated by thermospheric neutral wind,(2)the field-aligned electric field which appears when the electron density is low,(3)a effect of bending magnetic field,(4)an effect of fine structures of kinetic Alfven waves.It has been suggested that the Hall term is important in collisionless reconnection and Hall-MHD might be a better basis in simulations and for theory than resistive MHD. Some experimental evidence for this has been found at the magnetopause (MP) from GEOTAIL. It is our great wish to check and see with CLUSTER data if there is really a Hall … More current close to the reconnection line by looking at the out-of-phase magnetic field. CLUSTER consists of four identical subsatellites and they fly together. Each of them has magnetic and electric fields. Particles and plasma wave instruments onboard. When comparing our data with expectations that come from the published simulations there are a few difficulties, for example:(1)there is a density gradient across the MP, but all simulations have been so far done with a homogeneous background. The density gradient must make things less symmetric. For example, on which side would one expect the stronger Hall current, the magnetosheath or magnetosphere side?(2)What should 4 satellites see when flying through a specific reconnection scenario?For the first step to understand the collisionless reconnection process occurring around MP, we try to study a simple reconnection scenario with the 2-D Hall-MHD code that we previously applied to a magnetosphere-ionosphere coupling process associated with an auroral arc but in the present study we set the ion-neutral collision frequency to zero and take into consideration of pressure gradient terms, and modify the boundary conditions and background parameters accordingly. So far, our simulation code can address the MP scenarios rather well as observed with satellites such as GEOTAIL and CLUSTER. Less