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

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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