1. September 2006 CISM All Hand Meeting Properties of Solar Active Regions and Solar Eruptive Events Yang Liu -- Stanford University yliu@solar.stanford.edu

2. September 2006 CISM All Hand MeetingOutline Morphology patterns of active regions and solar eruptions; Morphology patterns of active regions and solar eruptions; Quantitative characteristics of active regions and solar eruptions; Quantitative characteristics of active regions and solar eruptions; More complex quantities of active regions and solar eruptions; More complex quantities of active regions and solar eruptions; Summary. Summary.

3. September 2006 CISM All Hand Meeting Morphology pattern Morphology patterns of flare/CMEs-productive ARs: Morphology patterns of flare/CMEs-productive ARs: Active regions not obeying Hale-law (e.g. Zirin 1988); Active regions not obeying Hale-law (e.g. Zirin 1988); δ-sunspots (e.g. Zirin 1988). δ-sunspots (e.g. Zirin 1988). Evolutionary characteristics of flare/CMEs-productive ARs: Evolutionary characteristics of flare/CMEs-productive ARs: Emerging magnetic flux regions occur within pre-existing ARs (e.g. Hagyard et al 1985); Emerging magnetic flux regions occur within pre-existing ARs (e.g. Hagyard et al 1985); Magnetic cancellation (e.g. Wang et al 1996); Magnetic cancellation (e.g. Wang et al 1996); Related shear motion of magnetic features with opposite polarities along the neutral line (e.g. ref…); Related shear motion of magnetic features with opposite polarities along the neutral line (e.g. ref…); Collision of magnetic features with opposite polarities (e.g. Wang et al 1991?). Collision of magnetic features with opposite polarities (e.g. Wang et al 1991?).

4. September 2006 CISM All Hand Meeting Quantitative characteristics Active regions with following characteristics are more flare/CMEs-productive: Active regions with following characteristics are more flare/CMEs-productive: High magnetic shear along the neutral line (e.g. Hagyard et al, 1984); High magnetic shear along the neutral line (e.g. Hagyard et al, 1984); High magnetic gradient toward the neutral line (e.g. Wang et al 2005); High magnetic gradient toward the neutral line (e.g. Wang et al 2005); Strong magnetic twist represented by force-free alpha (Falconer et al 2002)—actually can be presented by vertical electric current; Strong magnetic twist represented by force-free alpha (Falconer et al 2002)—actually can be presented by vertical electric current; Length of the highly sheared, strong-field neutral lines (Falconer et al 2002; 2003, 2006); Length of the highly sheared, strong-field neutral lines (Falconer et al 2002; 2003, 2006); Length of neutral lines with high magnetic gradient (Falconer et al 2003; Cui et al, 2006) Length of neutral lines with high magnetic gradient (Falconer et al 2003; Cui et al, 2006) Effective distance of active region that is defined as the distance of center-of-gravity of opposite polarities normalized by the active region size (Guo et al 2006); Effective distance of active region that is defined as the distance of center-of-gravity of opposite polarities normalized by the active region size (Guo et al 2006); In summary, the measures above describe properties of neutral line and magnetic field nearby.

5. September 2006 CISM All Hand Meeting More complex quantities of ARs Active regions with following properties are more flare/CME-productive. Active regions with following properties are more flare/CME-productive. Coronal bright loops appear to be much different from the potential field structure (Scherijver et al 2005): kind of 3D magnetic shear angle; Coronal bright loops appear to be much different from the potential field structure (Scherijver et al 2005): kind of 3D magnetic shear angle; Many singular points on the photosphere (Cui et al 2006); Many singular points on the photosphere (Cui et al 2006); Same sign of the magnetic twist and writhe in the active regions (Tian et al 2004); Same sign of the magnetic twist and writhe in the active regions (Tian et al 2004); Large magnetic energy and helicity flux rate in the active regions (LaBonte et al 2006); Large magnetic energy and helicity flux rate in the active regions (LaBonte et al 2006);LaBonte et al 2006LaBonte et al 2006 High relative free magnetic energy and high relative helicity in the active reions (Georgoulis et al, 2006). High relative free magnetic energy and high relative helicity in the active reions (Georgoulis et al, 2006).Georgoulis et al, 2006Georgoulis et al, 2006

6. September 2006 CISM All Hand Meeting Summary An eruptive active region needs to possess sufficient free energy, and magnetic field of the active region needs to evolve toward an unstable state. What we need to learn are: An eruptive active region needs to possess sufficient free energy, and magnetic field of the active region needs to evolve toward an unstable state. What we need to learn are: Mechanisms and processes of free energy buildup; Mechanisms and processes of free energy buildup; Processes of development of instability. Processes of development of instability. What we have learned from observations for an eruptive active region: What we have learned from observations for an eruptive active region: Big-size region with high potential energy; Big-size region with high potential energy; Properties of main neutral line and magnetic field nearby; Properties of main neutral line and magnetic field nearby; Evolutionary characteristics with dynamic behaviors (need to be more quantitatively characterized: it’s probably a key toward thoroughly understanding solar eruption and reliably forecasting space weather). Evolutionary characteristics with dynamic behaviors (need to be more quantitatively characterized: it’s probably a key toward thoroughly understanding solar eruption and reliably forecasting space weather). Threshold values for some indexes are suggested to distinguish eruptive active regions and non-eruptive active regions, but need further investigation (more detail). Threshold values for some indexes are suggested to distinguish eruptive active regions and non-eruptive active regions, but need further investigation (more detail).more detailmore detail