A case study of the plasma in the magneto-sheath using the numerical magnetosheath-magnetosphere model and THEMIS measure-ments

Polya Dobreva,Olga Nitcheva,Monio Kartalev,V.M Vassilev,Y.P Ivanova,S.G Nikolov,M.D Datcheva

doi:10.1051/matecconf/201814503004

Polya Dobreva, Olga Nitcheva + Show 5 more

Open Access

https://doi.org/10.1051/matecconf/201814503004

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Abstract

This paper presents a case study of the plasma parameters in the magnetosheath, based on THEMIS measurements. As a theoretical tool we apply the self-consistent magnetosheath-magnetosphere model. A specific aspect of the model is that the positions of the bow shock and the magnetopause are self-consistently determined. In the magnetosheath the distribution of the velocity, density and temperature is calculated, based on the gas-dynamic theory. The magnetosphere module allows for the calculation of the magnetopause currents, confining the magnetic field into an arbitrary non-axisymmetric magnetopause. The variant of the Tsyganenko magnetic field model is applied as an internal magnetic field model. As solar wind monitor we use measurements from the WIND spacecraft. The results show that the model quite well reproduces the values of the ion density and velocity in the magnetosheath. The simlicity of the model allows calulations to be perforemed on a personal computer, which is one of the mean advantages of our model.

Highlights

The magnetosheath plays very important role in the solar wind–magnetosphere-ionosphere interaction
The bow shock position is calculated as a part of the solution
During this interval the solar wind conditions are quiet as the plasma parameters vary in a narrow range

Summary

Introduction

The magnetosheath plays very important role in the solar wind–magnetosphere-ionosphere interaction. Understanding the mechanism of energy transfer requires the creation of adequate magnetosheath models. For given input parameters – the Mach number and polytropic index, and a given magnetopause shape, the model calculates the plasma parameters in the magnetosheath - density, velocity and temperature. The model was further developed including the distribution of the magnetic field in the magnetosheath [2]. As the solution (and in particular the velocity distribution) is known, the magnetic field in the magnetosheath can. The model is able to reproduce the real 3D geometry of the magnetosheath boundaries - bow shock (BS) and magnetopause (MP), including indentations around the cusp at the magnetopause.

Short description of the model

Input data

Magnetosheath measurements

Model results

Summary