Magnetic Field Goals – magnetic field & eruptive events

1. Magnetic Field Goals – magnetic field & eruptive events Yang Liu Stanford University

2. Sources and drivers of solar activity and disturbances. • Links between the internal processes and dynamics of the corona and heliosphere. • Applications for space-weather forecasts.

3. Sources and drivers of solar activity and disturbances (mechanisms of flares, CMEs, and filament eruption). • Change of magnetic field during eruption of filaments. • Change of magnetic field during flares. • Change of magnetic field during CMEs. • Emergence of magnetic flux and solar transient events.

4. Change of magnetic field during eruption of filaments.

5. Change of magnetic field during flares. u1 q1

6. Change of magnetic field during CMEs. Before CMEs Li et al. (2002) used Potential-Field Source-Surface model to detect occurrence of CMEs. After CMEs

7. Emerging magnetic flux and solar eruptive events. • Emerging flux associated with flares, eruption of filament, CMEs.

8. Sources and drivers of solar activity and disturbances (summary). • Magnetic field changes during transient events; emerging of magnetic flux associates with ( causes?) solar eruptive events. • Need a method to quantitatively describe this change. • Magnetic shear angle; Electric current; Source field; Others … • Need a method to describe variation of this change versus time. • Need to incorporate this information with further research, application for investigation of mechanisms of solar eruption and for space weather forecast. • Data requirements.

9. Links between the internal processes and dynamics of the corona and heliosphere. • Complexity and energetics of the solar corona (instability & energy buildup). • Relationship of small-scale and large-scale field. • Large-scale coronal field estimates.

10. 86 active regions with more than 3 major flares (Tian & Liu, 2003); • 99 active regions from Mees ( Canfield & Pevstov, 1998); • 203 bipolar active regions from Huairou (Tian, et al. 2001); • 22 bipolar active regions with long lifetime (at least one rotation) (Lepoz Fuentes, et al., 2003) A C B D

11. Relationship between small-scale and large-scale magnetic field. • To understand flares and CMEs; • To understand the role of active regions to large-scale field structure. Wang, et al. (2002) SAIC 3D MHD Simulation

12. Relationship between small-scale and large-scale magnetic field (cont’) Potential Field Model Force-free Field Model

13. Large-scale coronal field estimates (based on a Horizontal Current Current-Sheet Source-Surface model (HCCSSS)).

14. Links between the internal processes and dynamics of the corona and heliosphere (summary). • Processes for energy & instability buildup still remain unknown. Two mechanisms, the subphotospheric process or the photospheric shear motion, may in fact both work. • Observations show links between small-scale and large-scale fields, and also relates with solar eruptive events. • Coronal modeling discovers two types of large-scale closed field, one of them, helmet streamer, strongly associates with halo-CMEs. • Need a way to link those stuffs. • Helicity; magnetic topology; … • Data requirements: • Same as previous one.

15. Applications for space-weather forecasts. • Coronal magnetic structure and solar wind. • Based on coronal field extrapolation ( generally from a Potential Field Source Surface model) and Wang & Sheeley’s empirical model. • Space weather based on an integrated model coupling efforts of modeling from the Sun to the Earth. • Provide boundary, initial condition for the integrated model (observation of synoptic sun; solar coronal modeling from various models; etc.); • Provide data representative to solar transient turbulence (such as change of magnetic field described previously), solar eruptive mechanism, and etc… based on SDO’s observation and basic research worldwide.