System Science Tool for the Statistical Mapping of the Solar Wind - Magnetosheath - Magnetospheric System

Abstract:

The magnetosheath (MS) acts as a natural interface between the solar wind (SW) and magnetospheric (MSP) plasma and is therefore a key element in studying the driving of plasma properties in the inner MSP. However, understanding the behaviour of MS plasma properties due to the rapidly changing upstream conditions is no trivial matter and to date is not completely understood. Since the MS is situated between two very dynamic boundaries which respond directly to SW variations, their motion is significant to the order of several Earth radii. The combination of the spatial boundary variations and the non uniform nature of the SW not only make the compilation of statistical data problematic, but their interpretation is by no means straightforward. As a result, it is very difficult to build a complete picture of the global SW - MS - MSP system which accounts for upstream variations outside of the simulated environment. In the present study, we describe a statistical mapping methodology aimed at overcoming such difficulties. Our tool compiles statistical datasets for the MS and MSP in a normalised frame accounting for boundary motion, upstream SW variations and planetary aberration. We use THEMIS measurements for MS and MSP data whereas upstream estimates are provided by the OMNI database. Multiple datasets are compiled to produce statistical maps of the MS and MSP system and also to perform numerical analysis of the properties in each region. We use this methodology to study the presence of dawn/dusk asymmetries and their dependence on upstream conditions.