KU Leuven Centre for mathematical Plasma-Astrophysics Seminar
Title: Characteristics-based data-driven MHD boundary conditions for solar active regions
Speaker: Dylan Kee (NSO)
Abstract
Studying many of the open questions in the physics of the solar atmosphere (e.g. how the atmosphere above the temperature minimum region is heated, how and where the various types of solar wind arise, and what mechanisms trigger individual flares and CMEs) requires detailed knowledge of the 3D structure of plasma and magnetic fields above the photosphere. From a simulation perspective, studying the evolution of these properties can be achieved by so-called data-driven methods that take in an observationally inferred time-series of properties from the photosphere as a boundary condition. In this seminar I discuss a novel method for data-driving based on a characteristic decomposition of the hyperbolic MHD equations. This method guarantees that the boundaries are neither under- nor over-specified at each space and time point by specifying the boundary condition only in terms of simulation-inward propagating characteristics while still matching, as closely as possible, observations of primitive variables on a 2D surface over time. While the method is developed with data from the Helioseismic and Magnetic Imager onboard the Solar Dynamics Observatory and high resolution ground-based observations such as those from the Daniel K. Inouye Solar Telescope in mind, as a first proof of concept I present simulations drawing data from a ground truth ideal MHD simulation of an expanding spheromak, which can be taken as a simplified model for the emergence of a solar active region. I also discuss applications of this characteristics-based method to other types of boundaries, such as non-reflecting boundary conditions.
The seminars are in hybrid mode, you can follow in person in room 200B 02.16 or online at the (permanent) link:
https://eu.bbcollab.com/guest/7406a5ec00dc4ec6948200f9c769d454
