March 16, 2012, 12:00 pm - 1:00 pm
March 16, 2012, 12:00 pm - 1:00 pm, Heliophysics Director's Seminar
New Modeling Tools for Solar Active Region Evolution
Dr. Peter MacNeice,NASA Goddard Space Flight Center
The sun is the source of space weather, and the heliophysics research and forecasting communities have long sought accurate time dependent models of the dynamic Solar corona driven directly by observations of the changing surface magnetic field. In 2006 the NASA Living With A Star program funded us to develop a suite of modeling tools to fill this need, driven by the high resolution and high cadence observations of the photospheric magnetic field which it anticipated would be delivered by the Solar Dynamics Observatory. In the talk I will describe the design of our suite of tools, the type of investigations that they will support and the current status of our project.
Current-Sheet Formation and Reconnection at a Magnetic X Line in Particle-in-Cell Simulations
Dr. Carrie Black,NASA Goddard Space Flight Center/NPP
The integration of kinetic effects into global models for CME initiation is of great interest to the heliophysics community, particularly in the context of magnetic reconnection. Reconnection governs the large-scale energy release of magnetic fields in a variety of heliophysical and magnetospheric systems. We are examining the formation and reconnection of current sheets in a simple magnetic configuration, relevant to CMEs using high-resolution particle-in-cell (PIC) simulations. The initial minimum-energy magnetic field is perturbed by thermal pressure introduced into the particle distribution over time. Subsequently, the relaxation of this added stress leads self-consistently to the development of a current sheet that reconnects for imposed stress of sufficient strength. We compare the time-dependent evolution and final state of our PIC simulations with macroscopic magnetohydrodynamic simulations assuming both uniform and localized electrical resistivities. Finally, the implications of these results is discussed for understanding magnetic-reconnection onset and cessation at kinetic scales in dynamically formed current sheets, such as those occurring in the solar corona and terrestrial magnetotail.
Data Analysis Tools from the Community Coordinated Modeling Center
Dr. Rebekah Evans,NASA Goddard Space Flight Center/NPP
Coronal Mass Ejections (CMEs) are large-scale explosions of material and magnetic fields from the Sun that propagate through interplanetary space. When these eruptions impact the Earth’s magnetosphere, they can drive potentially dangerous space weather effects. Additionally, CME-driven shocks at heights of 2-3 solar radii have been associated with strong energetic particle events that can increase radiation in the near-Earth environment. In order to forecast these events, it is crucial to understand the early evolution of CMEs. I will present new simulation results for a modeled CME in an Alfven wave-driven solar wind with physically motivated wave dissipation as a heating source for the solar corona.