1. Session 6 Key Questions for Understanding This Unusual Solar Minimum Alan Gabriel Todd Hoeksema Janet Luhmann Bill Matthaeus Neil Sheeley

2. Key Questions for Understanding This Unusual Solar Minimum What is unique? Delayed Onset Asymmetry Meridional flow Polar Field → Coronal Holes Morphology Mass/Scale Height Irradiance Small-scale emergence Solar Wind Heliosphere CMEs / SEPs Cosmic Rays And more…

3. Key Questions for Understanding This Unusual Solar Minimum Our understanding and measurement of the system is much improved – as it absolutely must be to make progress on a complex and highly interconnected problem

4. Key Questions for Understanding This Unusual Solar Minimum We need to study this cycle in the context of previous cycles – the more the better. This is not our father’s cycle but our Grandfather’s cycle

5. Comparison of Large-Scale Corona in Cycles 21 & 23 Panels spaced By 12 rotations. CYCLE 23: Longer Fewer Contours Gradual Flattening Structures Persist More Dipolar in Declining Phase Structures Persist Thanks to Weak Poles Cycle 21Cycle 23

6. Antisymmetric Zonal Symmetric Zonal Old Polarity Surge 2003/4

7. Key Questions for Understanding This Unusual Solar Minimum Some care must be taken in defining concepts – your minimum may not be my minimum (etc.)

8. Key Questions for Understanding This Unusual Solar Minimum What are the key measurements and theoretical developments required so that we won’t be surprised when the next cycle rolls around?

9. From Wikipedia website Perspective Comes from Taking the Long View

10. What lies ahead?

11. Comparison of Large-Scale Corona in Cycles 22 & 23 Panels spaced By 12 rotations. Cycle 23: Fewer Contours Slower Flattening Structures Persist Thanks to Weak Poles Both Dipolar During Reversal Cycle 22Cycle 23

12. We have recently achieved unprecedented ability to observe, understand, and model the physical connections throughout the heliospheric system based on measurements of the solar magnetic field. Corroboration comes from images on SOHO and STEREO, in-situ measurements on SOHO, WIND, ACE, STEREO, other data from Hinode, TRACE, RHESSI, neutron monitors, etc. But does this tell us how the cycle will evolve?

13. Figures from MSFC website and from Cameron and Schussler, ApJ 2008 ? Best SSNmax empirical predictions are those based on rise time of cycle

14. Wang et al., ApJ 2005 A way to get and relate variable polar fields and IMFs via surface transport and changing meridional flow

15. Figures: Brun and Toomre, ApJ 2002, SOHO website What’s missing: essential dynamo processes in the Sun determining flux generation, emergence and transport