Global Transport of Magnetic Energy in Active Regions on the Sun

University Of California-Berkeley, Berkeley CA

Investigators

Abstract

Unstable magnetic structures in the atmosphere of the Sun are the root source of eruptive events at the Sun that can cause severe perturbations in the near-Earth space environment and upper atmosphere. Our society is becoming increasingly dependent on technological assets that are vulnerable to these, so-called, space weather events. Consequently, predicting the occurrence and detailed nature of such events is of critical importance to minimizing their damage. Understanding the creation and dynamic development of large-scale magnetically active regions in the solar atmosphere is currently a topic of intense research in solar physics. This project will perform a series of highly complex and computationally demanding numerical simulations to illuminate the basic physical processes and interactions at play. The investigation is the first to describe the coupling between the solar interior and atmosphere over the entire range of physical conditions and disparate spatial and temporal scales characteristic of large active regions. It will do so by utilizing newly developed advanced computational techniques and access to supercomputer resources. The further development and test of this active region model constitute a critical step towards establishing a predictive capability for solar events. The numerical experiments performed in this study will generate data sets that are useful to other ongoing efforts to model solar magnetic activity and the numerical techniques have many additional applications, particularly in the field of astrophysics. Finally, the work product will be made publicly available under an OpenSource license allowing it to be used by other researchers or educators with an interest in describing physical systems using a three-dimensional, Cartesian or spherical, radiative magneto-hydro-dynamic model. The principal scientific objective is to better understand both the coupling between the solar interior and atmosphere as active regions emerge and evolve, and the transport of magnetic energy over the range of physical conditions, and the disparate spatial and temporal scales of the convection zone-to-corona system. To address this objective, the newly developed spherical version of the radiative-magneto-hydro-dynamic code RADMHD will be used to perform numerical simulations of active region magnetic flux emergence through the upper convection into the corona. The simulations are unique in that they will, for the first time, produce self-consistent and self-contained models of the emergence and evolution of large-scale active region magnetic fields spanning the upper convection zone-to-corona in spherical geometry. Magnetic flux will be introduced into the domain from below, using data from existing calculations of magnetic flux emergence through the deep interior, and the transport of electromagnetic energy throughout the domain will be studied as active region magnetic fields interact with convective turbulence and make their way radially outward into the model atmosphere. Three sets of numerical simulations of flux emergence on three distinct spatial scales will be performed: (1) a single active region, (2) two active regions in close proximity, and (3) two widely separated active regions in a global magnetic environment.