3D Model of an Active Region Coronal Magnetic Field

PI: Peter Macneice
Team-Maintained Web Site: http://einstein.physics.drexel.edu/~solarweather/index.html

Target description: A primary goal of NASA’s Living With a Star (LWS) Program is the development of first-principles-based models for the coupled Sun-Earth and Sun-Solar System, similar in spirit to the first principles models for the lower terrestrial atmosphere. Such models can act as tools for science investigations, as prototypes and test beds for prediction and specification capabilities, as frameworks for linking disparate data sets at vantage points throughout the Sun-Solar System, and as strategic planning aids for enabling exploration of outer space and testing new mission concepts. To begin the process of developing and integrating models for all the components of the Sun-Earth and Sun-Solar System chain,the LWS Targeted Research and Technology (TR&T) Science Definition Team identified these models and their integration as strategic capabilities that are critical for the TR&T program and recommended that they be funded as a distinct program element within the TR&T.

Goals and measures of success: A quantitative 3D model for the slowly evolving magnetic field of a complex active region. This topic was chosen to reflect the fact that in the next five years we will have high resolution, high cadence solar observations from unique vantage points in the heliosphere such as STEREO, Solar-B, and SDO for assimilation into models. As observations from other new missions become available we will be concentrating on those strategic areas.

Types of solicited investigations: A primary objective of LWS is to enable the development of physics-based modeling of the Sun-Heliosphere and Sun-Earth systems. Since the energy source for the most destructive space weather throughout the solar system is the magnetic field of a complex active region, a clear prerequisite for LWS to meet its objective is a robust model for thi field. An accurate physics-based model for the 3D structure and slow evolution of the field and, especially, its free energy, is essential if we are to understand and predict the onset and development of CME/Eruptive Flares. An active region field model is also essential for understanding and predicting the solar UV/XUV emission that drive Earth’s upper atmosphere. Furthermore, a robust model for the active region field would be an invaluable research tool for advancing our basic understanding of the photosphere – corona – heliosphere coupling. Given that Solar-B and SDO will be delivering revolutionary new observations of the photospheric fields and of coronal structure, and given that a great deal of work has been performed by a number of groups on magnetic field extrapolation, it is now timely to develop a nextgeneration community tool that can meet the needs of LWS.

- Essential Features:
• Use vector magnetic field data of the kind expected from Solar-B and SDO/HMI as input;
• Find physically consistent flow fields/electric fields from vector magnetograms for time dependent (quasi-steady) magnetic field evolution, including flux emergence/cancellation and apparent shearing motions;
• Determine the 3D vector magnetic field and electric currents of a complete active region over as large a scale as possible;
• Include the capability to interface with global coronal-heliospheric field models;
• Provides user-friendly interfaces and graphical interface for runs on demand by the general research community, including capability for zooming in on small portions of the simulation domain, and ability to analyze magnetic topology;
• Provide the flexibility for quick-turn-around runs;
• Working version to be delivered to CCMC within 3 years, final production version within five years.

- Desirable Features:
• Includes the ability to incorporate, as input, magnetic field observations from different heights in the solar atmosphere;
• Includes the ability to incorporate, as input, photospheric velocity field data;
• Includes the ability to incorporate, as input, coronal imaging data;
• Allows for a variety of user-selectable field-determination methods.