A Model of the Induced Martian Magnetospheric Magnetic Field Based on MAVEN Observations: Methodology and First Results

Abstract:

Mars has a unique magnetic environment in the solar system. Not only does it have an induced magnetosphere as a result of the existence of an atmosphere and the lack of the global magnetic field, but its strong localized crustal magnetic fields can create noticeable effects on the induced magnetosphere near the planet. The configuration of the induced magnetosphere is therefore constantly changing because of planetary rotation and the non-steady interplanetary field. The quantitative knowledge of the induced Martian magnetospheric magnetic field is important in estimating the escape of charged particles from Mars, thus helping achieve the science objectives of MAVEN.

This study constructs an empirical model of the induced Martian magnetospheric magnetic field by adopting some of the approaches used for modeling the Earth’s magnetosphere as well as by incorporating new elements unique to the Martian magnetic field environment. The induced magnetosphere consists of components associated with the tail current sheet, the Mars counterpart of the Chapman-Ferraro current, and the draped fields. The crustal magnetic fields based on prior studies are also included. The empirical model has a set of parameters whose values can be obtained through matching MAVEN observations. Specifically, the MAG instrument provides the magnetic field data, and particle data are used to help locate boundaries between regions.

Compared with global numerical models of the induced Martian magnetosphere, the empirical model has an apparent advantage in its capability of rapidly estimating the magnetic field configurations for different solar wind conditions. We will describe the methodology for modeling the induced Martian magnetospheric magnetic field and demonstrate the initial results based on the first year of MAVEN data.