Interfacing MHD Single Fluid and Kinetic Exospheric Solar Wind Models and Comparing Their Energetics

TL;DR

This paper compares a kinetic exospheric solar wind model with a magnetohydrodynamic (MHD) model, analyzing their energetics and how they simulate solar wind properties from the Sun to Earth, incorporating observational data and physical processes.

Contribution

It introduces an interface between a kinetic exospheric model and a data-driven MHD model, providing a detailed comparison of their energetics and physical assumptions.

Findings

Both models produce similar solar wind speed and density profiles at 1AU.

Inclusion of suprathermal electrons affects coronal heating and acceleration.

Energetic profiles differ significantly at certain heliocentric distances.

Abstract

An exospheric kinetic solar wind model is interfaced with an observation-driven single fluid magnetohydrodynamic (MHD) model. Initially, a photospheric magnetogram serves as observational input in the fluid approach to extrapolate the heliospheric magnetic field. Then semi-empirical coronal models are used for estimating the plasma characteristics up to a heliocentric distance of 0.1AU. From there on a full MHD model which computes the three-dimensional time-dependent evolution of the solar wind macroscopic variables up to the orbit of the Earth is used. After interfacing the density and velocity at the inner MHD boundary, we compare with the results of a kinetic exospheric solar wind model based on the assumption of Maxwell and Kappa velocity distribution functions for protons and electrons respectively, as well as with \textit{in situ} observations at 1AU. This provides insight on more physically detailed processes, such as coronal heating and solar wind acceleration, that naturally arise by inclusion of suprathermal electrons in the model. We are interested in the profile of the solar wind speed and density at 1AU, in characterizing the slow and fast source regions of the wind and in comparing MHD with exospheric models in similar conditions. We calculate the energetics of both models from low to high heliocentric distances.